Professor John Ellis is an international expert in medical and veterinary protozoology. He completed a PhD on leishmaniasis with Professor J.M. Crampton at the Liverpool School of Tropical Medicine in 1986, and subsequently did postdoctoral research on Eimeria vaccines (at Houghton Poultry Research Station) and parasite phylogeny (at Flinders University of South Australia). He was appointed to the academic staff of the University Technology, Sydney, in 1992 as a Lecturer in Microbiology.
Over the last nineteen years John Ellis has continued to study parasitic protozoa of both veterinary and medical importance. His main research interests are focused on translational research that includes development of vaccines and diagnostics for protozoal diseases of economic importance, such as Neospora caninum and Dientamoeba fragilis. He was awarded a DSc by Liverpool University in 2006 for pioneering research on the biology of cyst-forming coccidia.
He has published 170 peer-reviewed research papers and is the lead inventor on over 40 patents granted from his research.
- Editor for the journals Parasitology and Journal for Medical Microbiology.
- International Reader, Australian Research Council (since 2007)
- Member, NH&MRC microbiology grant review panel (several occasions)
- Fellow, Royal Society for Tropical Medicine and Hygiene
- Member of the Australian, British and American Societies for Parasitology
Can supervise: YES
I am interested in many areas of veterinary and medical parasitology with a special focus on applied, practical aspects such as development and validation of new diagnostic tests and vaccines for parasites such as Neospora caninum and Dientamoeba fragilis.
My main interest is the development of vaccines to N. caninum. For some years this has included the development and validation of a live vaccine approach in laboratory mice and cattle, but more recently focus has been on surface antigens of N. caninum and the mechanisms of animal responses to infection by N. caninum using microarray technology/mining of genome sequence data.
In medical parasitology, my research is focussed on enteric parasites that cause disease, and in particular D. fragilis. In collaboration with Damien Stark, Jock Harkness and Debbie Marriott of St. Vincent’s Hospital (Sydney) we have been documenting the importance of this parasite as a pathogen and a cause of diarrhoea. Introduction of real time PCR into the diagnostic microbiology laboratory has improved the detection of D. fragilis in clinical specimens so much, we now consider it a common cause of disease. We have made recent advances in the culture of the organism that is now allowing us to perform molecular analyses of the proteome. In addition, we are developing a new generation of diagnostic tests for the microbiology laboratory.
I am keen to foster external research collaborations in the general area of parasitology and to supervise research students in the workplace.
John Ellis is the subject coordinator for the third year subject Molecular Biology 2 (91335). This subject is an introduction to eukaryotic gene structure and expression, as well as the study of genomes and their sequence content.
He is also the subject coordinator of the subject Parasitology (91352). This subject introduces the discipline as a clinical subject, and covers the diverse areas of medical and veterinary parasitology.
He also supervises postgraduate research students in his research areas. His present research students are:
Larissa Calarco, is studying methods for mutation detection
Alexa Kaufer, is studying molecular evolution of the flagellates
Rory Gough, is studying genes of Dientamoeba fragilis
Ineka Gow, is studying leishmaniasis diagnostics
Calarco, L & Ellis, J 2020, 'Contribution of introns to the species diversity associated with the apicomplexan parasite, Neospora caninum', PARASITOLOGY RESEARCH, vol. 119, no. 2, pp. 431-445.View/Download from: Publisher's site
Second and third generation sequencing methods are crucial for population genetic studies, and variant detection is a popular approach for exploiting this sequence data. While mini- and microsatellites are historically useful markers for studying important Protozoa such as Toxoplasma and Plasmodium spp., detecting non-repetitive variants such as those found in genes can be fundamental to investigating a pathogen's biology. These variants, namely single nucleotide polymorphisms and insertions and deletions, can help elucidate the genetic basis of an organism's pathogenicity, identify selective pressures, and resolve phylogenetic relationships. They also have the added benefit of possessing a comparatively low mutation rate, which contributes to their stability. However, there is a plethora of variant analysis tools with nuanced pipelines and conflicting recommendations for best practise, which can be confounding. This lack of standardisation means that variant analysis requires careful parameter optimisation, an understanding of its limitations, and the availability of high quality data. This review explores the value of variant detection when applied to non-model organisms such as clinically important protozoan pathogens. The limitations of current methods are discussed, including special considerations that require the end-users' attention to ensure that the results generated are reproducible, and the biological conclusions drawn are valid.
Gough, R, Barratt, J, Stark, D & Ellis, J 2020, 'Diversity profiling of xenic cultures of Dientamoeba fragilis following systematic antibiotic treatment and prospects for genome sequencing.', Parasitology (Cambridge), vol. 147, no. 1, pp. 29-38.View/Download from: Publisher's site
The presence of bacterial DNA in Dientamoeba fragilis DNA extracts from culture poses a substantial challenge to sequencing the D. fragilis genome. However, elimination of bacteria from D. fragilis cultures has proven difficult in the past, presumably due to its dependence on some unknown prokaryote/s. This study explored options for removal of bacteria from D. fragilis cultures and for the generation of genome sequence data from D. fragilis. DNA was extracted from human faecal samples and xenic D. fragilis cultures. Extracts were subjected to 16S ribosomal DNA bacterial diversity profiling. Xenic D. fragilis cultures were then subject to antibiotic treatment regimens that systematically removed bacterial species depending on their membrane structure (Gram-positive or Gram-negative) and aerobic requirements. The impact of these treatments on cultures was assessed by 16S amplicon sequencing. Prior to antibiotic treatment, the cultures were dominated by Gram-negative bacteria. Addition of meropenem to cultures eliminated anaerobic Gram-negative bacteria, but it also led to protozoan death after 5 days incubation. The seeding of meropenem resistant Klebsiella pneumoniae strain KPC-2 into cultures before treatment by meropenem prevented death of D. fragilis cells beyond this 5 day period, suggesting that one or more species of Gram-negative bacteria may be an essential nutritional requirement for D. fragilis. Gram-positive cells were completely eliminated using vancomycin without affecting trophozoite growth. Finally, this study shows that genome sequencing of D. fragilis is feasible following bacterial elimination from cultures as the result of the major advances occurring in bioinformatics. We provide evidence on this fact by successfully sequencing the D. fragilis 28S large ribosomal DNA subunit gene using culture-derived DNA.
Kaufer, A, Stark, D & Ellis, J 2020, 'A review of the systematics, species identification and diagnostics of the Trypanosomatidae using the maxicircle kinetoplast DNA: from past to present', International Journal for Parasitology.View/Download from: Publisher's site
© 2020 Australian Society for Parasitology The Trypanosomatid family are a diverse and widespread group of protozoan parasites that belong to the higher order class Kinetoplastida. Containing predominantly monoxenous species (i.e. those having only a single host) that are confined to invertebrate hosts, this class is primarily known for its pathogenic dixenous species (i.e. those that have two hosts), serving as the aetiological agents of the important neglected tropical diseases including leishmaniasis, American trypanosomiasis (Chagas disease) and human African trypanosomiasis. Over the past few decades, a multitude of studies have investigated the diversity, classification and evolutionary history of the trypanosomatid family using different approaches and molecular targets. The mitochondrial-like DNA of the trypanosomatid parasites, also known as the kinetoplast, has emerged as a unique taxonomic and diagnostic target for exploring the evolution of this diverse group of parasitic eukaryotes. This review discusses recent advancements and important developments that have made a significant impact in the field of trypanosomatid systematics and diagnostics in recent years.
Noisang, C, Meyer, W, Sawangjaroen, N, Ellis, J & Lee, R 2020, 'Molecular Detection of Antimalarial Drug Resistance in Plasmodium vivax from Returned Travellers to NSW, Australia during 2008-2018', PATHOGENS, vol. 9, no. 2.View/Download from: Publisher's site
Barratt, JL & Ellis, J 2019, 'Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen - CORRIGENDUM.', Parasitology, pp. 1-1.View/Download from: Publisher's site
Calarco, L & Ellis, J 2019, 'Annotating the 'hypothetical' in hypothetical proteins: In-silico analysis of uncharacterised proteins for the Apicomplexan parasite, Neospora caninum.', Veterinary parasitology, vol. 265, pp. 29-37.View/Download from: Publisher's site
Neospora caninum is a parasite of veterinary and economic importance, affecting beef and dairy cattle industries globally. While this species has been recognised as a serious cause of disease in cattle and dogs for over 30 years, treatment and control options are still not available. Furthermore, whilst vaccination was identified as the most economic control strategy, vaccine discovery programs require new leads to investigate as vaccines. The current lack of gene annotation available for N. caninum, especially compared to the closely related model organism, Toxoplasma gondii, considerably hinders vaccine related research. Moreover, due to the high degree of similarity between the two organisms, a significant amount of gene annotation available for N. caninum stems from sequence homology between the species. However, there is a plethora of literature identifying conserved virulence factors between members of the Apicomplexa, which suggests that key players are contributing to successful parasite invasion, motility, and host cell attachment. In this study, bioinformatic approaches classified 125 uncharacterised proteins within the N. caninum genome, as transmembrane proteins with signal peptide sequences. Functional annotation assigned enriched gene ontologies for cell-adhesion, ATP binding, protein serine/threonine phosphatase complex, immune system process, antigen binding, and proteolysis. Additionally, 32 of these proteins were also identified as adhesins, or having adhesin-like properties, which were further characterised through the discovery of domains and gene ontology, to reveal their potential functional significance as virulence factors for N. caninum. This study identifies a new, small subset of proteins within N. caninum, that may be involved in host-cell interaction, parasite adhesion, and invasion, thereby implicating them as potential targets to exploit in the development of control options against the disease.
Cao, M, Ellis, JT, Marriott, D, Harkness, J & Stark, D 2019, 'Evaluation of the EasyScreen Protozoan Detection Kit for the diagnosis of Entamoeba histolytica.', Pathology, vol. 51, no. 4, pp. 426-428.View/Download from: Publisher's site
Gough, R, Ellis, J & Stark, D 2019, 'Comparison and Recommendations for Use of Dientamoeba fragilis Real-Time PCR Assays.', Journal of Clinical Microbiology, vol. 57, no. 5.View/Download from: Publisher's site
Dientamoeba fragilis is a gastrointestinal trichomonad parasite whose pathogenicity is yet to be determined. The difficulty involved in microscopically diagnosing D. fragilis in feces led to the development of real-time PCR methodologies for the detection of D. fragilis in stool samples. Prevalence studies in Europe show much higher levels of infection where a laboratory-developed real-time assay is the predominant assay for the detection of Dientamoeba fragilis than in regions that use the EasyScreen assay for detection of gastrointestinal pathogens. The aim of this study was to compare a commercially available Dientamoeba fragilis assay (Genetic Signatures EasyScreen assay) to a widely used laboratory-developed real-time PCR method. Two hundred fifty fecal samples were screened using the laboratory-developed real-time assay on four real-time PCR platforms producing a number of discrepant results. Limit-of-detection studies were undertaken to attempt to resolve sensitivity for each platform tested. The presence or absence of Dientamoeba fragilis DNA in discrepant samples was shown using PCR amplicon next-generation sequencing. Eukaryotic 18S diversity profiling was conducted on discrepant samples to identify the presence or absence of additional protozoan species in samples that may be responsible for cross-reactivity seen in these samples. The results revealed the potential for multiple false-positive results when using the laboratory-developed real-time assay across multiple real-time platforms using manufacturer default settings. This report provides recommendations to resolve these issues where possible and suggestions for future prevalence studies, and it emphasizes the EasyScreen assay as the molecular method of choice as well as the need for standardization of detection assays across all nations screening for D. fragilis.
Gow, I, Millar, D, Ellis, J, Melki, J & Stark, D 2019, 'Semi-Quantitative, Duplexed qPCR Assay for the Detection of Leishmania spp. Using Bisulphite Conversion Technology.', Tropical Medicine and Infectious Disease, vol. 4, no. 4.View/Download from: Publisher's site
Leishmaniasis is caused by the flagellated protozoan Leishmania, and is a neglected tropical disease (NTD), as defined by the World Health Organisation (WHO). Bisulphite conversion technology converts all genomic material to a simplified form during the lysis step of the nucleic acid extraction process, and increases the efficiency of multiplex quantitative polymerase chain reaction (qPCR) reactions. Through utilization of qPCR real-time probes, in conjunction with bisulphite conversion, a new duplex assay targeting the 18S rDNA gene region was designed to detect all Leishmania species. The assay was validated against previously extracted DNA, from seven quantitated DNA and cell standards for pan-Leishmania analytical sensitivity data, and 67 cutaneous clinical samples for cutaneous clinical sensitivity data. Specificity was evaluated by testing 76 negative clinical samples and 43 bacterial, viral, protozoan and fungal species. The assay was also trialed in a side-by-side experiment against a conventional PCR (cPCR), based on the Internal transcribed spacer region 1 (ITS1 region). Ninety-seven percent of specimens from patients that previously tested positive for Leishmania were positive for Leishmania spp. with the bisulphite conversion assay, and a limit of detection (LOD) of 10 copies per PCR was achieved, while the LOD of the ITS1 methodology was 10 cells/1000 genomic copies per PCR. This method of rapid, accurate and simple detection of Leishmania can lead to improved diagnosis, treatment and public health outcomes.
Kaufer, A, Barratt, J, Stark, D & Ellis, J 2019, 'The complete coding region of the maxicircle as a superior phylogenetic marker for exploring evolutionary relationships between members of the Leishmaniinae.', Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases, vol. 70, pp. 90-100.View/Download from: Publisher's site
The mitochondrial DNA (mtDNA) is a potentially valuable phylogenetic marker given its presence across all eukaryotic taxa and its relative conservation in structure and sequence. In trypanosomatids, a homologue of the mtDNA referred to as the maxicircle DNA, is located within a specialised structure in the single mitochondrion of the trypanosomatids called the kinetoplast; a high molecular weight network of DNA composed of thousands of catenated minicircles and a smaller number of larger maxicircles. Unique to the kinetoplastid protists, the maxicircle component of this complex network could represent a desirable target for taxonomic inquiry that may also facilitate exploration of the evolutionary history of this important group of parasites. The aim of this study was to investigate the phylogenetic value of the trypanosomatid maxicircle for these applications. Maxicircle sequences were obtained either by assembling raw sequence data publicly accessible in online databases (i.e., NCBI), or by amplification of novel maxicircle sequences from trypanosomatid DNA using long-range (LR) PCR with subsequent Illumina sequencing. This procedure facilitated the generation of nearly complete maxicircle sequences (i.e., excluding the divergent region) for numerous dixenous and monoxenous trypanosomatid species. Annotation of each maxicircle sequence confirmed that their structure was conserved across all taxa examined. Phylogenetic analyses confirmed that Z. australiensis showed a greater genetic relatedness with the dixenous trypanosomatids of the genera Leishmania and Endotrypanum, as opposed to members of the monoxenous genera Crithidia and Leptomonas. Additionally, molecular clock analysis supported that the dixenous Leishmaniinae appeared approximately 75 million years ago during the breakup of Gondwana. In line with previous studies, our results support the Supercontinents hypothesis regarding the origin of dixenous Leishmaniinae. Ultimately, we demonstrate that the ma...
Kaufer, A, Ellis, J & Stark, D 2019, 'Identification of clinical infections of Leishmania imported into Australia: Revising speciation with polymerase chain reaction-RFLP of the kinetoplast maxicircle', American Journal of Tropical Medicine and Hygiene, vol. 101, no. 3, pp. 590-601.View/Download from: Publisher's site
Copyright © 2019 by The American Society of Tropical Medicine and Hygiene. Leishmaniasis is a vector-borne disease caused by protozoan parasites of the Leishmania genus. In Australia, leishmaniasis is an imported disease that is presenting itself at increased rates because of international travel, the influx of immigrants, and deployment of military operations to endemic regions. Although Leishmania species are morphologically indistinguishable, there is a strong correlation between some causative species of leishmaniasis and the subsequent response to the treatments available and patient outcome. Consequently, identification of the infective species is imperative as misidentification can result in the administering of an ineffective drug. The aim of this study was to develop a simple diagnostic tool with high sensitivity and specificity, which is capable of detecting the presence of the parasite and accurately differentiating the causative species in question. Using the advantageous properties of the maxi-circle kinetoplast DNA, a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) targeting the ND7 gene was developed for the analysis of imported cases of human leishmaniasis in Australia. Designed as a dual analysis, concurrent PCR of Leishmania maxi-circle DNA and digestion with two separate enzymes (NlaIII and HpyCH4IV), this study provides an appraisal on 24 imported cases of leishmaniasis between 2008 and 2017. Five Leishmania species were reported, with members of the Viannia subgenus being the most common. The implementation of novel diagnostic procedures for leishmaniasis such as the one reported here is needed to establish a gold standard practice for the diagnosis and treatment of leishmaniasis.
Kaufer, A, Stark, D & Ellis, J 2019, 'Evolutionary Insight into the Trypanosomatidae Using Alignment-Free Phylogenomics of the Kinetoplast.', Pathogens (Basel, Switzerland), vol. 8, no. 3.View/Download from: Publisher's site
Advancements in next-generation sequencing techniques have led to a substantial increase in the genomic information available for analyses in evolutionary biology. As such, this data requires the exponential growth in bioinformatic methods and expertise required to understand such vast quantities of genomic data. Alignment-free phylogenomics offer an alternative approach for large-scale analyses that may have the potential to address these challenges. The evolutionary relationships between various species within the trypanosomatid family, specifically members belonging to the genera Leishmania and Trypanosoma have been extensively studies over the last 30 years. However, there is a need for a more exhaustive analysis of the Trypanosomatidae, summarising the evolutionary patterns amongst the entire family of these important protists. The mitochondrial DNA of the trypanosomatids, better known as the kinetoplast, represents a valuable taxonomic marker given its unique presence across all kinetoplastid protozoans. The aim of this study was to validate the reliability and robustness of alignment-free approaches for phylogenomic analyses and its applicability to reconstruct the evolutionary relationships between the trypanosomatid family. In the present study, alignment-free analyses demonstrated the strength of these methods, particularly when dealing with large datasets compared to the traditional phylogenetic approaches. We present a maxicircle genome phylogeny of 46 species spanning the trypanosomatid family, demonstrating the superiority of the maxicircle for the analysis and taxonomic resolution of the Trypanosomatidae.
Noisang, C, Prosser, C, Meyer, W, Chemoh, W, Ellis, J, Sawangjaroen, N & Lee, R 2019, 'Molecular detection of drug resistant malaria in Southern Thailand.', Malaria Journal, vol. 18, no. 1.View/Download from: Publisher's site
BACKGROUND:Drug resistance within the major malaria parasites Plasmodium vivax and Plasmodium falciparum threatens malaria control and elimination in Southeast Asia. Plasmodium vivax first-line treatment drug is chloroquine together with primaquine, and the first-line treatment for P. falciparum malaria is artemisinin in combination with a partner drug. Plasmodium vivax and P. falciparum parasites resistant to their respective first-line therapies are now found within Southeast Asia. The resistance perimeters may include high transmission regions of Southern Thailand which are underrepresented in surveillance efforts. METHODS:This study investigated blood samples from malaria centres in Southern Thailand. Genetic loci associated with drug resistance were amplified and sequenced. Drug resistance associated genes Pvmdr1, Pvcrt-o, Pvdhfr, and Pvdhps were characterized for 145 cases of P. vivax malaria, as well as the artemisinin resistance-associated Pfkelch13 gene from 91 cases of P. falciparum malaria. RESULTS:Plasmodium vivax samples from Southern Thai provinces showed numerous chloroquine and antifolate resistance-associated mutations, including SNP and Pvcrt-o K10-insertion combinations suggestive of chloroquine resistant P. vivax phenotypes. A high proportion of the C580Y coding mutation (conferring artemisinin resistance) was detected in P. falciparum samples originating from Ranong and Yala (where the mutation was previously unreported). CONCLUSIONS:The results demonstrate a risk of chloroquine and antifolate resistant P. vivax phenotypes in Southern Thailand, and artemisinin resistant P. falciparum observed as far south as the Thai-Malaysian border region. Ongoing surveillance of antimalarial drug resistance markers is called for in Southern Thailand to inform case management.
Calarco, L, Barratt, J & Ellis, J 2018, 'Genome Wide Identification of Mutational Hotspots in the Apicomplexan Parasite Neospora caninum and the Implications for Virulence', GENOME BIOLOGY AND EVOLUTION, vol. 10, no. 9, pp. 2417-2431.View/Download from: Publisher's site
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2018, 'A Gene-Based Positive Selection Detection Approach to Identify Vaccine Candidates Using Toxoplasma gondii as a Test Case Protozoan Pathogen.', Frontiers in Genetics, vol. 9.View/Download from: Publisher's site
Over the last two decades, various in silico approaches have been developed and refined that attempt to identify protein and/or peptide vaccines candidates from informative signals encoded in protein sequences of a target pathogen. As to date, no signal has been identified that clearly indicates a protein will effectively contribute to a protective immune response in a host. The premise for this study is that proteins under positive selection from the immune system are more likely suitable vaccine candidates than proteins exposed to other selection pressures. Furthermore, our expectation is that protein sequence regions encoding major histocompatibility complexes (MHC) binding peptides will contain consecutive positive selection sites. Using freely available data and bioinformatic tools, we present a high-throughput approach through a pipeline that predicts positive selection sites, protein subcellular locations, and sequence locations of medium to high T-Cell MHC class I binding peptides. Positive selection sites are estimated from a sequence alignment by comparing rates of synonymous (dS) and non-synonymous (dN) substitutions among protein coding sequences of orthologous genes in a phylogeny. The main pipeline output is a list of protein vaccine candidates predicted to be naturally exposed to the immune system and containing sites under positive selection. Candidates are ranked with respect to the number of consecutive sites located on protein sequence regions encoding MHCI-binding peptides. Results are constrained by the reliability of prediction programs and quality of input data. Protein sequences from Toxoplasma gondii ME49 strain (TGME49) were used as a case study. Surface antigen (SAG), dense granules (GRA), microneme (MIC), and rhoptry (ROP) proteins are considered worthy T. gondii candidates. Given 8263 TGME49 protein sequences processed anonymously, the top 10 predicted candidates were all worthy candidates. In particular, the top ten included ROP5 and...
Prosser, C, Meyer, W, Ellis, J & Lee, R 2018, 'Evolutionary ARMS Race: Antimalarial Resistance Molecular Surveillance.', Trends in parasitology, vol. 34, no. 4, pp. 322-334.View/Download from: Publisher's site
Molecular surveillance of antimalarial drug resistance markers has become an important part of resistance detection and containment. In the current climate of multidrug resistance, including resistance to the global front-line drug artemisinin, there is a consensus to upscale molecular surveillance. The most salient limitation to current surveillance efforts is that skill and infrastructure requirements preclude many regions. This includes sub-Saharan Africa, where Plasmodium falciparum is responsible for most of the global malaria disease burden. New molecular and data technologies have emerged with an emphasis on accessibility. These may allow surveillance to be conducted in broad settings where it is most needed, including at the primary healthcare level in endemic countries, and extending to the village health worker.
Prosser, C, Meyer, W, Ellis, J & Lee, R 2018, 'Resistance screening and trend analysis of imported falciparum malaria in NSW, Australia (2010 to 2016).', PLoS ONE, vol. 13, no. 5, pp. e0197369-e0197369.View/Download from: Publisher's site
BACKGROUND:The World Health Organization currently recommends artemisinin (along with a partner drug) as the global frontline treatment for Plasmodium falciparum malaria. Artemisinin resistant P. falciparum are now found throughout the greater Mekong subregion of South East Asia. Several polymorphisms in the parasite's kelch gene have been demonstrated to confer artemisinin resistance. While genotypes within the greater Mekong subregion are thoroughly examined in the literature, P. falciparum populations within several areas that do not (yet) have endemic resistance are underrepresented. RESULTS:This investigation characterised the Pfkelch13 propeller domains from 153 blood samples of 140 imported cases of P. falciparum malaria in New South Wales from 2010 to 2016. A low level of propeller domain diversity was observed, including the C580Y coding mutation most strongly associated with artemisinin resistance in South East Asia. The resistance genotype was found in a sample originating in Papua New Guinea, where this mutation, or artemisinin treatment failure, have not been previously reported. Sequencing a panel of geographically informative polymorphisms within the organellar genomes identified the C580Y parasite as having Oceanic origins. Patient data analysis revealed that New South Wales, Australia, P. falciparum malaria cases often originated from regions with limited drug resistance screening. CONCLUSIONS:The C580Y finding from outside of the greater Mekong subregion supports the consensus to upscale molecular surveillance of artemisinin resistance outside of South East Asia. The genetic screening results identify a risk of importing resistant falciparum malaria to Australia, supporting an ongoing surveillance protocol to pre-empt treatment failure and contribute to global data gathering.
Zajaczkowski, P, Mazumdar, S, Conaty, S, Ellis, JT & Fletcher-Lartey, SM 2018, 'Epidemiology and associated risk factors of giardiasis in a peri-urban setting in New South Wales Australia.', Epidemiology and Infection, vol. 147, pp. 1-9.View/Download from: Publisher's site
Giardiasis is one of the most important non-viral causes of human diarrhoea. Yet, little is known about the epidemiology of giardiasis in the context of developed countries such as Australia and there is a limited information about local sources of exposure to inform prevention strategies in New South Wales. This study aimed to (1) describe the epidemiology of giardiasis and (2) identify potential modifiable risk factors associated with giardiasis that are unique to south-western Sydney, Australia. A 1:2 matched case-control study of 190 confirmed giardiasis cases notified to the South-Western Local Health District Public Health Unit from January to December 2016 was employed to investigate the risk factors for giardiasis. Two groups of controls were selected to increase response rate; Pertussis cases and neighbourhood (NBH) controls. A matched analysis was carried out for both control groups separately. Variables with a significant odds ratio (OR) in the univariate analysis were placed into a multivariable regression for each matched group, respectively. In the regression model with the NBH controls, age and sex were controlled as potential confounders. Identified risk factors included being under 5 years of age (aOR = 7.08; 95% confidence intervals (CI) 1.02-49.36), having a household member diagnosed with a gastrointestinal illness (aOR = 15.89; 95% CI 1.53-164.60) and having contact with farm animals, domestic animals or wildlife (aOR = 3.03; 95% CI 1.08-8.54). Cases that travelled overseas were at increased risk of infection (aOR = 19.89; 95% CI 2.00-197.37) when compared with Pertussis cases. This study provides an update on the epidemiology and associated risk factors of a neglected tropical disease, which can inform enhanced surveillance and prevention strategies in the developed metropolitan areas.
Barratt, J, Kaufer, A, Peters, B, Craig, D, Lawrence, A, Roberts, T, Lee, R, McAuliffe, G, Stark, D & Ellis, J 2017, 'Isolation of Novel Trypanosomatid, Zelonia australiensis sp. nov. (Kinetoplastida: Trypanosomatidae) Provides Support for a Gondwanan Origin of Dixenous Parasitism in the Leishmaniinae.', PLoS Neglected Tropical Diseases, vol. 11, no. 1, pp. 1-26.View/Download from: Publisher's site
The genus Leishmania includes approximately 53 species, 20 of which cause human leishmaniais; a significant albeit neglected tropical disease. Leishmaniasis has afflicted humans for millennia, but how ancient is Leishmania and where did it arise? These questions have been hotly debated for decades and several theories have been proposed. One theory suggests Leishmania originated in the Palearctic, and dispersed to the New World via the Bering land bridge. Others propose that Leishmania evolved in the Neotropics. The Multiple Origins theory suggests that separation of certain Old World and New World species occurred due to the opening of the Atlantic Ocean. Some suggest that the ancestor of the dixenous genera Leishmania, Endotrypanum and Porcisia evolved on Gondwana between 90 and 140 million years ago. In the present study a detailed molecular and morphological characterisation was performed on a novel Australian trypanosomatid following its isolation in Australia's tropics from the native black fly, Simulium (Morops) dycei Colbo, 1976. Phylogenetic analyses were conducted and confirmed this parasite as a sibling to Zelonia costaricensis, a close relative of Leishmania previously isolated from a reduviid bug in Costa Rica. Consequently, this parasite was assigned the name Zelonia australiensis sp. nov. Assuming Z. costaricensis and Z. australiensis diverged when Australia and South America became completely separated, their divergence occurred between 36 and 41 million years ago at least. Using this vicariance event as a calibration point for a phylogenetic time tree, the common ancestor of the dixenous genera Leishmania, Endotrypanum and Porcisia appeared in Gondwana approximately 91 million years ago. Ultimately, this study contributes to our understanding of trypanosomatid diversity, and of Leishmania origins by providing support for a Gondwanan origin of dixenous parasitism in the Leishmaniinae.
Donahoe, SL, Phalen, DN, McAllan, BM, O'Meally, D, McAllister, MM, Ellis, J & Slapeta, J 2017, 'Differential Gamma Interferon-and Tumor Necrosis Factor Alpha-Driven Cytokine Response Distinguishes Acute Infection of a Metatherian Host with Toxoplasma gondii and Neospora caninum', INFECTION AND IMMUNITY, vol. 85, no. 6.View/Download from: Publisher's site
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2017, 'On the application of reverse vaccinology to parasitic diseases: a perspective on feature selection and ranking of vaccine candidates.', International journal for parasitology, vol. 47, no. 12, pp. 779-790.View/Download from: Publisher's site
Reverse vaccinology has the potential to rapidly advance vaccine development against parasites, but it is unclear which features studied in silico will advance vaccine development. Here we consider Neospora caninum which is a globally distributed protozoan parasite causing significant economic and reproductive loss to cattle industries worldwide. The aim of this study was to use a reverse vaccinology approach to compile a worthy vaccine candidate list for N. caninum, including proteins containing pathogen-associated molecular patterns to act as vaccine carriers. The in silico approach essentially involved collecting a wide range of gene and protein features from public databases or computationally predicting those for every known Neospora protein. This data collection was then analysed using an automated high-throughput process to identify candidates. The final vaccine list compiled was judged to be the optimum within the constraints of available data, current knowledge, and existing bioinformatics programs. We consider and provide some suggestions and experience on how ranking of vaccine candidate lists can be performed. This study is therefore important in that it provides a valuable resource for establishing new directions in vaccine research against neosporosis and other parasitic diseases of economic and medical importance.
Trypanosomatids are protozoan parasites of the class Kinetoplastida predominately restricted to invertebrate hosts (i.e. possess a monoxenous life-cycle). However, several genera are pathogenic to humans, animals and plants, and have an invertebrate vector that facilitates their transmission (i.e. possess a dixenous life-cycle). Phytomonas is one dixenous genus that includes several plant pathogens transmitted by phytophagous insects. Trypanosoma and Leishmania are dixenous genera that infect vertebrates, including humans, and are transmitted by hematophagous invertebrates. Traditionally, monoxenous trypanosomatids such as Leptomonas were distinguished from morphologically similar dixenous species based on their restriction to an invertebrate host. Nonetheless, this criterion is somewhat flawed as exemplified by Leptomonas seymouri which reportedly infects vertebrates opportunistically. Similarly, Novymonas and Zelonia are presumably monoxenous genera yet sit comfortably in the dixenous clade occupied by Leishmania. The isolation of Leishmania macropodum from a biting midge (Forcipomyia spp.) rather than a phlebotomine sand fly calls into question the exclusivity of the Leishmania-sand fly relationship, and its suitability for defining the Leishmania genus. It is now accepted that classic genus-defining characteristics based on parasite morphology and host range are insufficient to form the sole basis of trypanosomatid taxonomy as this has led to several instances of paraphyly. While improvements have been made, resolution of evolutionary relationships within the Trypanosomatidae is confounded by our incomplete knowledge of its true diversity. The known trypanosomatids probably represent a fraction of those that exist and isolation of new species will help resolve relationships in this group with greater accuracy. This review incites a dialogue on how our understanding of the relationships between certain trypanosomatids has shifted, and discusses new knowledge t...
Barratt, J, Chan, D, Sandaradura, I, Malik, R, Spielman, D, Lee, R, Marriott, D, Harkness, J, Ellis, J & Stark, D 2016, 'Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen', PARASITOLOGY, vol. 143, no. 9, pp. 1087-1118.View/Download from: Publisher's site
Chan, D, Barratt, J, Roberts, T, Phillips, O, Slapeta, J, Ryan, U, Marriott, D, Harkness, J, Ellis, J & Stark, D 2016, 'Detection of Dientamoeba fragilis in animal faeces using species specific real time PCR assay', VETERINARY PARASITOLOGY, vol. 227, pp. 42-47.View/Download from: Publisher's site
Fletcher-Lartey, S, Andresen, D, Van Hal, S, Merif, J, Stark, D, Rawlinson, W, Harkness, J & Ellis, J 2016, 'Comparison of enteric protozoan infections in four Australian hospitals: variable tests and variable results', Parasitology Open, vol. 2, no. e13, pp. 1-8.View/Download from: Publisher's site
There is limited evidence of the prevalence of enteric protozoon infections in developed settings. We estimated the prevalence of enteric protozoa and evaluated the outcome of testing algorithms used in hospital settings in Sydney, Australia. This retrospective study assessed microbiological data from four public clinical laboratories. Pooled data from the four hospitals revealed the most common enteric protozoon detected was Blastocystis spp. in an average of 5·4% of cases, followed by Giardia intestinalis (1·1%) and Dientamoeba fragilis (0·8%). Protozoon detection rates between hospitals were significantly different and could be based on multiple factors. The modified iron haematoxylin staining method, consistently detected higher rates of Blastocystis spp., and G. intestinalis in comparison with microscopy of wet preparations, as well as higher rates of G. intestinalis and Cryptosporidium when compared with enzyme immunoassay. The study concludes that there are multiple factors that contribute to the variability in protozoa detection rates in metropolitan hospitals, including widespread variability in the testing protocols for enteric protozoa, individual and population characteristics. A gold standard approach for diagnosis of enteric protozoa is recommended. Molecular diagnostic methods such as polymerase chain reaction would provide consistency across laboratories and yield more reliable estimates of the actual prevalence of enteric protozoa.
Stark, D, Barratt, J, Chan, D & Ellis, JT 2016, 'Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel', CLINICAL MICROBIOLOGY REVIEWS, vol. 29, no. 3, pp. 553-580.View/Download from: Publisher's site
Barratt, JLN, Cao, M, Stark, DJ & Ellis, JT 2015, 'The Transcriptome Sequence of Dientamoeba fragilis Offers New Biological Insights on its Metabolism, Kinome, Degradome and Potential Mechanisms of Pathogenicity', PROTIST, vol. 166, no. 4, pp. 389-408.View/Download from: Publisher's site
Chan, D, Barratt, J, Roberts, T, Lee, R, Shea, M, Marriott, D, Harkness, J, Malik, R, Jones, M, Aghazadeh, M, Ellis, J & Stark, D 2015, 'The Prevalence of Angiostrongylus cantonensis/mackerrasae Complex in Molluscs from the Sydney Region', PLOS ONE, vol. 10, no. 5.View/Download from: Publisher's site
Goodswen, SJ, Barratt, JLN, Kennedy, PJ & Ellis, JT 2015, 'Improving the gene structure annotation of the apicomplexan parasite Neospora caninum fulfils a vital requirement towards an in silico-derived vaccine', International Journal for Parasitology, pp. 305-318.View/Download from: Publisher's site
Neospora caninum is an apicomplexan parasite which can cause abortion in cattle, instigating major economic burden. Vaccination has been proposed as the most cost-effective control measure to alleviate this burden. Consequently the overriding aspiration for N. caninum research is the identification and subsequent evaluation of vaccine candidates in animal models. To save time, cost and effort, it is now feasible to use an in silico approach for vaccine candidate prediction. Precise protein sequences, derived from the correct open reading frame, are paramount and arguably the most important factor determining the success or failure of this approach. The challenge is that publicly available N. caninum sequences are mostly derived from gene predictions. Annotated inaccuracies can lead to erroneously predicted vaccine candidates by bioinformatics programs. This study evaluates the current N. caninum annotation for potential inaccuracies. Comparisons with annotation from a closely related pathogen, Toxoplasma gondii, are also made to distinguish patterns of inconsistency. More importantly, a mRNA sequencing (RNA-Seq) experiment is used to validate the annotation. Potential discrepancies originating from a questionable start codon context and exon boundaries were identified in 1943 protein coding sequences. We conclude, where experimental data were available, that the majority of N. caninum gene sequences were reliably predicted. Nevertheless, almost 28% of genes were identified as questionable. Given the limitations of RNA-Seq, the intention of this study was not to replace the existing annotation but to support or oppose particular aspects of it. Ideally, many studies aimed at improving the annotation are required to build a consensus. We believe this study, in providing a new resource on gene structure and annotation, is a worthy contributor to this endeavour.
Reichel, MP, Moore, DP, Hemphill, A, Ortega-Mora, LM, Dubey, JP & Ellis, JT 2015, 'A live vaccine against Neospora caninum abortions in cattle', VACCINE, vol. 33, no. 11, pp. 1299-1301.View/Download from: Publisher's site
Roberts, T, Barratt, J, Sandaradura, I, Lee, R, Harkness, J, Marriott, D, Ellis, J & Stark, D 2015, 'Molecular Epidemiology of Imported Cases of Leishmaniasis in Australia from 2008 to 2014', PLOS ONE, vol. 10, no. 3.View/Download from: Publisher's site
Roberts, T, Bush, S, Ellis, J, Harkness, J & Stark, D 2015, 'In Vitro Antimicrobial Susceptibility Patterns of Blastocystis', ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, vol. 59, no. 8, pp. 4417-4423.View/Download from: Publisher's site
Fletcher, S, Sibbritt, D, Stark, D, Harkness, J, Rawlinson, W, Andresen, D, van Hal, S, Merif, J & Ellis, JT 2015, 'Descriptive epidemiology of infectious gastrointestinal illnesses in Sydney,Australia, 2007–2010', Western Pacific Surveillance and Response Journal, vol. 6, no. 4, pp. 7-16.View/Download from: Publisher's site
Banik, GR, Stark, DJ, Rashid, H & Ellis, JT 2014, 'Recent Advances in Molecular Biology of Parasitic Viruses', Infectious Disorders Drug Targets, vol. 14, no. 3, pp. 155-167.View/Download from: Publisher's site
The numerous protozoa that can inhabit the human gastro-intestinal tract are known, yet little is understood of the viruses which infect these protozoa. The discovery, morphologic details, purification methods of virus-like particles, genome and proteome of the parasitic viruses, Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, and the Eimeria sp. are described in this review. The protozoan viruses share many common features: most of them are RNA or double-stranded RNA viruses, ranging between 5 and 8 kilobases, and are spherical or icosahedral in shape with an average diameter of 30-40 nm. These viruses may influence the function and pathogenicity of the protozoa which they infect, and may be important to investigate from a clinical perspective. The viruses may be used as specific genetic transfection vectors for the parasites and may represent a research tool. This review provides an overview on recent advances in the field of protozoan viruses.
Fletcher, SM, Caprarelli, G, Merif, J, Andresen, D, Van Hal, S, Stark, DJ & Ellis, JT 2014, 'Epidemiology and Geographical distribution of enteric protozoan infections in Sydney, Australia', Journal of Public Health Research, vol. 3, no. 2, pp. 83-91.View/Download from: Publisher's site
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2014, 'Discovering a vaccine against neosporosis using computers: is it feasible?', Trends In Parasitology, vol. 30, no. 8, pp. 401-411.View/Download from: Publisher's site
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2014, 'Enhancing In Silico Protein-Based Vaccine Discovery for Eukaryotic Pathogens Using Predicted Peptide-MHC Binding and Peptide Conservation Scores', PLOS ONE, vol. 9, no. 12.View/Download from: Publisher's site
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2014, 'Vacceed: a high-throughput in silico vaccine candidate discovery pipeline for eukaryotic pathogens based on reverse vaccinology', Bioinformatics, vol. 30, no. 16, pp. 2381-2383.
Reichel, MP, McAllister, MM, Pomroy, BE, Campero, C, Ortega-Mora, L & Ellis, JT 2014, 'Control options for Neospora caninum - is there anything new or are we going backwards?', Parasitology, vol. 141, no. 11, pp. 1455-1470.View/Download from: Publisher's site
Ren, J, Ellis, JT & Li, J 2014, 'Influenza A HA's conserved epitopes and broadly neutralizing antibodies: a prediction method', Journal of Bioinformatics and Computational Biology, vol. 12, no. 5.View/Download from: Publisher's site
Ren, J, liu, Q, Ellis, J & Li, J 2014, 'Tertiary structure-based prediction of conformational B-cell epitopes through B factors', Bioinformatics, vol. 30, no. 12, pp. 264-273.View/Download from: Publisher's site
Motivation: B-cell epitope is a small area on the surface of an antigen that binds to an antibody. Accurately locating epitopes is of critical importance for vaccine development. Compared with wet-lab methods, computational methods have strong potential for efficient and large-scale epitope prediction for antigen candidates at much lower cost. However, it is still not clear which features are good determinants for accurate epitope prediction, leading to the unsatisfactory performance of existing prediction methods.
Method and results: We propose a much more accurate B-cell epitope prediction method. Our method uses a new feature B factor (obtained from X-ray crystallography), combined with other basic physicochemical, statistical, evolutionary and structural features of each residue. These basic features are extended by a sequence window and a structure window. All these features are then learned by a two-stage random forest model to identify clusters of antigenic residues and to remove isolated outliers. Tested on a dataset of 55 epitopes from 45 tertiary structures, we prove that our method significantly outperforms all three existing structure-based epitope predictors. Following comprehensive analysis, it is found that features such as B factor, relative accessible surface area and protrusion index play an important role in characterizing B-cell epitopes. Our detailed case studies on an HIV antigen and an influenza antigen confirm that our second stage learning is effective for clustering true antigenic residues and for eliminating self-made prediction errors introduced by the first-stage learning.
Roberts, TJ, Ellis, JT, Harkness, JL, Marriott, DJ & Stark, DJ 2014, 'Treatment failure in patients with chronic Blastocystis infection', Journal of Medical Microbiology, vol. 63, no. 2, pp. 252-257.View/Download from: Publisher's site
This article reports long-term infection and treatment failure in 18 symptomatic individuals infected with Blastocystis spp. Patients were initially treated with either metronidazole, iodoquinol or triple combination therapy consisting of nitazoxanide, furazolidone and secnidazole. Following treatment, resolution of clinical symptoms did not occur and follow-up testing revealed ongoing infection with the same subtype. Patients then underwent secondary treatment with a variety of antimicrobial agents but remained symptomatic with Blastocystis spp. still present in faeces. Sequencing of the SSU rDNA was completed on all isolates and four subtypes were identified in this group: ST1, ST3, ST4 and ST5. This study highlights the lack of efficacy of several commonly used antimicrobial regimens in the treatment of Blastocystis and the chronic nature of some infections. It also demonstrates the need for further research into treatment options for Blastocystis infection.
Roberts, TJ, Stark, DJ, Harkness, JL & Ellis, JT 2014, 'Update on the Molecular Epidemiology and Diagnostic Tools for Blastocystis sp', Journal of Medical Microbiology & Diagnosis, vol. 3, no. 1.View/Download from: Publisher's site
Roberts, TJ, Stark, DJ, Harkness, JL & Ellis, JT 2014, 'Update on the pathogenic potential and treatment options for Blastocystis sp', Gut Pathogens, vol. 6, pp. 1-9.View/Download from: Publisher's site
Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2014, 'Activity of benzimidazoles against Dientamoeba fragilis (Trichomonadida, Monocercomonadidae) in vitro and correlation of beta-tubulin sequences as an indicator of resistance', Parasite, vol. 21.View/Download from: Publisher's site
Stark, DJ, Garcia, L, Barratt, JL, Phillips, O, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2014, 'Description of Dientamoeba fragilis cyst and precystic forms from human samples', Journal Of Clinical Microbiology, vol. 52, no. 7, pp. 2680-2683.View/Download from: Publisher's site
Stark, DJ, Roberts, TJ, Ellis, JT, Marriott, DJ & Harkness, JL 2014, 'Evaluation of the EasyScreen Enteric Parasite Detection Kit for the detection of Blastocystis spp., Cryptosporidium spp., Dientamoeba fragilis, Entamoeba complex, and Giardia intestinalis from clinical stool samples', Diagnostic Microbiology And Infectious Disease, vol. 78, no. 2, pp. 149-152.View/Download from: Publisher's site
The aim of this study was to evaluate the EasyScreen Enteric Parasite Detection Kit (Genetic Signatures, Sydney, Australia) for the detection and identification of 5 common enteric parasites: Blastocystis spp., Cryptosporidium spp., Dientamoeba fragilis, Entamoeba complex, and Giardia intestinalis in human clinical samples. A total of 358 faecal samples were included in the study. When compared to real-time PCR and microscopy, the EasyScreen Enteric Parasite Detection Kit exhibited 92-100% sensitivity and 100% specificity and detected all commonly found genotypes and subtypes of clinically important human parasites. No cross reactivity was detected in stool samples containing various other bacterial, viral, and/or protozoan species. The EasyScreen PCR assay was able to provide rapid, sensitive, and specific simultaneous detection and identification of the 5 most important diarrhoea-causing enteric parasites that infect humans. It should be noted, however, that the EasyScreen Kit does not substitute for microscopy or for additional PCRs as it does not detect the pathogenic Coccidia spp. Cystoisospora belli or Cyclospora cayetanensis and it does not differentiate between pathogenic and nonpathogenic Entamoeba spp. This study also highlights the lack of sensitivity demonstrated by microscopy; as such, molecular methods should be considered the diagnostic method of choice for enteric parasites.
Fletcher, S, McLaws, M & Ellis, JT 2013, 'Prevalence of gastrointestinal pathogens in developed and developing countries: systematic review and meta-analysis', Journal of Public Health Research, vol. 2, no. 1, pp. 42-53.View/Download from: Publisher's site
Diarrhoeal illness is a leading cause of child mortality and morbidity worldwide. There are no precise or current estimates of the types and prevalence of pathogens associated with diarrheal illnesses in developed and developing settings. This systematic review assessed data from 60 studies published in the English language from five developing regions and developed countries worldwide to provide regional estimates of enteric pathogens affecting children. The random-effect method was used to establish the weighted average prevalence of pathogens in adults and children for each region. Significantly more pathogens were reported by studies from developing regions compared with Organisation for Economic Co-operation and Development countries (P<0.016). The identification rates of pathogens from community based and hospital based studies were similar (58.5% and 58.1% respectively, P<0.619). The overall detection of enteric pathogens in developing countries was higher in adults (74.8%; 95% CI 63.1-83.8%) compared with children (56.7%; 95% CI 53.0-60.4%) (P<0.001). Rotavirus was the most frequently detected pathogen in all regions with the highest rate, 24.8% (95% CI 18.0-33.1%), detected in the developed countries. This systematic review is the first to provide an estimate of the prevalence of enteric pathogens associated with diarrhoeal illnesses in adults and children in developed and developing settings. While pathogen detection rate is greater in developing regions the consistently high prevalence of rotavirus in both developed and developing settings underscores the urgent need for access to rotavirus vaccines. Increased travel between developing and developed countries increases disease risk, and hence developed countries have a vested interest in supporting vaccine accessibility in developing settings.
Fletcher, S, Van Hal, S, Andresen, D, McLaws, M, Stark, DJ, Harkness, JL & Ellis, JT 2013, 'Gastrointestinal pathogen distribution in symptomatic children in Sydney, Australia', Journal of Epidemiology and Global Health, vol. 3, no. 1, pp. 11-21.View/Download from: Publisher's site
There is limited information on the causes of paediatric diarrhoea in Sydney. This cross-sectional study used clinical and microbiological data to describe the clinical features and pathogens associated with gastrointestinal illnesses for children presenting to two major public hospitals in Sydney with diarrhoea, for the period January 2007December 2010. Of 825 children who tested positive for an enteric pathogen, 430 medical records were reviewed. Adenovirus, norovirus and rotavirus were identified in 20.8%, 20.3% and 21.6% of reviewed cases, respectively. Younger children were more likely to have adenovirus and norovirus compared with rotavirus (P = 0.001). More viruses were detected in winter than in the other three seasons (P = 0.001). Rotavirus presented a distinct seasonal pattern with the lowest rates occurring in the warm months and peaking in the cooler months. Adenovirus showed a less consistent monthly trend, and norovirus detection increased in the cooler months (P = 0.008). A decline in the number of rotavirus cases was observed after mid-2008. The majority of childhood diarrhoeal illnesses leading to hospital presentations in Sydney are caused by enteric viruses with most infections following clear seasonal patterns. However, a sustained decrease in the incidence of rotavirus infections has been observed over the study period.
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2013, 'A guide to in silico vaccine discovery for eukaryotic pathogens', Briefings in Bioinformatics, vol. 14, no. 6, pp. 753-774.View/Download from: Publisher's site
In this article, a framework for an in silico pipeline is presented as a guide to high-throughput vaccine candidate discovery for eukaryotic pathogens, such as helminths and protozoa. Eukaryotic pathogens are mostly parasitic and cause some of the most damaging and difficult to treat diseases in humans and livestock. Consequently, these parasitic pathogens have a significant impact on economy and human health. The pipeline is based on the principle of reverse vaccinology and is constructed from freely available bioinformatics programs. There are several successful applications of reverse vaccinology to the discovery of subunit vaccines against prokaryotic pathogens but not yet against eukaryotic pathogens. The overriding aim of the pipeline, which focuses on eukaryotic pathogens, is to generate through computational processes of elimination and evidence gathering a ranked list of proteins based on a scoring system. These proteins are either surface components of the target pathogen or are secreted by the pathogen and are of a type known to be antigenic. No perfect predictive method is yet available; therefore, the highest-scoring proteins from the list require laboratory validation.
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2013, 'A novel strategy for classifying the output from an in silico vaccine discovery pipeline for eukaryotic pathogens using machine learning algorithms', BMC Bioinformatics, vol. 14, no. 1, pp. 315-327.View/Download from: Publisher's site
An in silico vaccine discovery pipeline for eukaryotic pathogens typically consists of several computational tools to predict protein characteristics. The aim of the in silico approach to discovering subunit vaccines is to use predicted characteristics to identify proteins which are worthy of laboratory investigation. A major challenge is that these predictions are inherent with hidden inaccuracies and contradictions. This study focuses on how to reduce the number of false candidates using machine learning algorithms rather than relying on expensive laboratory validation. Proteins from Toxoplasma gondii, Plasmodium sp., and Caenorhabditis elegans were used as training and test datasets.
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2013, 'A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present', Infection, Genetics and Evolution, vol. 13, no. 1, pp. 133-150.View/Download from: Publisher's site
This paper is a review of current knowledge on Neospora caninum in the context of other apicomplexan parasites and with an emphasis on: life cycle, disease, epidemiology, immunity, control and treatment, evolution, genomes, and biological databases and web resources. N. caninum is an obligate, intracellular, coccidian, protozoan parasite of the phylum Apicomplexa. Infection can cause the clinical disease neosporosis, which most notably is associated with abortion in cattle. These abortions are a major root cause of economic loss to both the dairy and beef industries worldwide. N. caninum has been detected in every country in which a study has been specifically conducted to detect this parasite in cattle. The major mode of transmission in cattle is transplacental (or vertical) transmission and several elements of the N. caninum life cycle are yet to be studied in detail. The outcome of an infection is inextricably linked to the precise timing of the infection coupled with the status of the immune system of the dam and foetus. There is no community consensus as to whether it is the dams pro-inflammatory cytotoxic response to tachyzoites that kills the foetus or the tachyzoites themselves. From economic analysis the most cost-effective approach to control neosporosis is a vaccine. The perfect vaccine would protect against both infection and the clinical disease, and this implies a vaccine is needed that can induce a non-foetopathic cell mediated immunity response. Researchers are beginning to capitalise on the vast potential of -omics data (e.g. genomes, transcriptomes, and proteomes) to further our understanding of pathogens but especially to identify vaccine and drug targets. The recent publication of a genome for N. caninum offers vast opportunities in these areas.
Munasinghe, VS, Vella, N, Ellis, JT, Windsor, PA & Stark, DJ 2013, 'Cyst formation and fecal-oral transmission of Dientamoeba fragilis - the missing link in the life cycle of an emerging pathogen', International Journal For Parasitology, vol. 43, no. 11, pp. 879-883.View/Download from: Publisher's site
Dientamoeba fragilis is a protozoan parasite emerging as a cause of diarrhoea and irritable-bowel-like gastrointestinal disease in humans with a propensity for establishing long-term, chronic infections in humans. Although Dientamoeba was discovered over a century ago its life cycle and mode of transmission is not known. No cyst stage has been described and no animal models are presently available for the study of this parasite. Here we describe the establishment of an animal model using laboratory rodents, the fulfilling of Kochs postulates, and the discovery of a new cyst stage in the life cycle of D. fragilis. Our demonstration of long-term parasite carriage by rodents and prolonged shedding of cysts, together with elevated levels of calprotectin in the stool, confirms the capacity of this organism to cause disease and indicates dientamoebiasis should be considered in the differential diagnosis of gastrointestinal diseases such as Inflammatory Bowel Syndrome (IBS). Finally, we suggest that the cyst stage described here is the vehicle that mediates faecaloral transmission of D. fragilis between hosts.
Reichel, MP, Ayanegui-AlcÃ©rrec, M, Gondim, L & Ellis, JT 2013, 'What is the global economic impact of Neospora caninum in cattle - The billion dollar question', International Journal For Parasitology, vol. 43, pp. 133-142.View/Download from: Publisher's site
Neospora caninum is regarded as one of the most important infectious causes of abortions in cattle worldwide, yet the global economic impact of the infection has not been established. A systematic review of the economic impact of N. caninum infections/abortions was conducted, searching PubMed with the terms 'cattle' and 'Neospora'. This yielded 769 publications and the abstracts were screened for economically relevant information (e.g. abortion prevalence and risk, serological prevalence). Further analysis was restricted to countries with at least five relevant publications. In total, 99 studies (12.9%) from 10 countries contained data from the beef industry (25 papers (25.3%)) and 72 papers (72.8%) from the dairy industry (with the remaining two papers (2.0%) describing general abortion statistics). The total annual cost of N. caninum infections/abortions was estimated to range from a median US $1.1 million in the New Zealand beef industry to an estimated median total of US $546.3 million impact per annum in the US dairy population. The estimate for the total median N. caninum-related losses exceeded US $1.298 billion per annum, ranging as high as US $2.380 billion. Nearly two-thirds of the losses were incurred by the dairy industry (US $842.9 million). Annual losses on individual dairy farms were estimated to reach a median of US $1,600.00, while on beef farms these costs amounted to just US $150.00. Pregnant cows and heifers were estimated to incur, on average, a loss due to N. caninum of less than US $20.00 for dairy and less than US $5.00 for beef. These loss estimates, however, rose to ~US $110.00 and US $40.00, respectively, for N. caninum-infected pregnant dairy and beef cows. This estimate of global losses due to N. caninum, with the identification of clear target markets (countries, as well as cattle industries), should provide an incentive to develop treatment options and/or vaccines.
Roberts, TJ, Stark, DJ, Harkness, JL & Ellis, JT 2013, 'Subtype distribution of Blastocystis isolates from a variety of animals from New South Wales, Australia', Veterinary Parasitology, vol. 196, no. 1-2, pp. 85-89.View/Download from: Publisher's site
A total of 438 stool samples from 38 different species of animal from seven different locations were studied for the presence of Blastocystis. PCR analysis was completed on all samples and DNA sequence data from the rDNA were submitted to subtype allocation. There was a total of 80 (18%) sequences from 18 species, and nine different subtypes were identified ST1, ST2, ST3, ST4, ST5, ST7, ST11, ST12 and ST13. This is the first report of Blastocystis from the eastern grey kangaroo, red kangaroo, wallaroo, snow leopard and ostrich. This study highlights the need for further investigation into the genetic diversity of Blastocystis which could help show the zoonotic potential of Blastocystis.
Roberts, TJ, Stark, DJ, Harkness, JL & Ellis, JT 2013, 'Subtype distribution of Blastocystis isolates identified in a Sydney population and pathogenic potential of Blastocystis', European Journal of Clinical Microbiology & Infectious Diseases, vol. 32, no. 3, pp. 335-343.View/Download from: Publisher's site
Blastocystis is one of the most common enteric parasites present in humans. There is still much uncertainty about the pathogenic potential of this parasite, and it was suggested that its pathogenicity could be subtype-related. This report aimed to study 98 Blastocystis isolates found in human stool specimens to identify the subtypes present and carry out phylogenetic analysis on these isolates. This study also aimed to show the relationship between subtype and symptoms. Five-hundred and thirteen stool samples were submitted to five different diagnostic techniques for the detection of Blastocystis. Polymerase chain reaction (PCR)-positive samples were then sequenced and the small subunit (SSU) rDNA sequences were aligned and submitted to phylogenetic analysis. Ninety-eight samples were positive by any of the diagnostic methods for Blastocystis and 96 were positive by PCR. There were seven different subtypes (1, 2, 3, 4, 6, 7 and 8) identified by PCR and sequencing. This is the first large-scale study to examine the occurrence of Blastocystis in Australia. This study reports the high incidence of subtype 3 (44 %) in this population and discusses the emerging idea of subtype-dependent pathogenicity
Weber, F, Jackson, JA, Sobecki, B, Choromanski, L, Olsen, M, Meinert, T, Frank, R, Reichel, MP & Ellis, JT 2013, 'On the efficacy and safety of vaccination in cattle with live tachyzoites of Neospora caninum for the prevention of Neospora-associated fetal loss in cattle', Clinical and Vaccine Immunology, vol. 20, no. 1, pp. 99-105.View/Download from: Publisher's site
Infection of cattle with Neospora caninum may result in abortion or the birth of a congenitally infected calf. Vaccination with live N. caninum protects against experimental infection of cattle and mice, and the naturally attenuated Nc-Nowra strain of N. caninum is of particular interest as a potential vaccine candidate. Vaccination of heifers prior to breeding with live Nc-Nowra tachyzoites by either the subcutaneous or the intravenous route reduced the rate of abortion and the presence of the parasite in calves as determined by PCR and serology after infection of cows with a virulent isolate. Protected fractions were 55.6% to 85.2% depending on the route of vaccination and growth conditions of the vaccine strain, with cryopreserved Nc-Nowra tachyzoites being less effective, with a 25.9% protected fraction. Vaccination appeared to reduce the rate of pregnancy after artificial insemination in some groups compared to nonvaccinated, nonchallenged controls. One animal that was vaccinated but not challenged experienced an abortion, but Nc-Nowra could not be detected in any of the cows in this group or their progeny. This study confirms that live vaccination can be an effective method of preventing neosporosis in cattle and yet highlights the technical hurdle of preservation of live parasites that must be overcome for a vaccine to be commercially successful.
Banik, G, Birch, D, Stark, DJ & Ellis, JT 2012, 'A microscopic description and ultrastructural characterization of Dientamoeba fragilis: an emerging cause of human enteric disease', International Journal For Parasitology, vol. 42, pp. 139-153.View/Download from: Publisher's site
Dientamoeba fragilis is a pathogenic trichomonad found in the gastrointestinal tract of humans and is implicated as a cause of diarrhoea. Despite its discovery over a century ago, there has been no recent thorough description of this parasite by microscopy. Scanning electron microscopy, transmission electron microscopy, confocal and light microscopy were therefore used to characterise D. fragilis populations growing in xenic culture. Two different populations smooth and ruffled cells were identifiable by scanning electron microscopy. No flagella, pelta structures, undulating membrane or pseudocyst-like forms were present. The organelles in D. fragilis were analysed by transmission electron microscopy; like Trichomonas and Histomonas, D. fragilis contains hydrogenosomes that presumably represent the site of anaerobic respiration. The nuclear morphology of D. fragilis trophozoites grown in vitro and trophozoites from clinical isolates were also compared by confocal microscopy and light microscopy. The majority of cells grown in culture were mononucleate while most cells in permanent stained faecal smears were binucleate. The two nuclei of D. fragilis are morphologically indistinguishable and contain equivalent amounts of DNA as determined by DAPI staining. The approximate cell and nuclear volume of four isolates of D. fragilis were measured and shown to be comparable to other trichomonads. In addition, the discovery of a virus-like particle is reported, to our knowledge for the first time in D. fragilis. This study therefore provides extensive and novel details of the ultrastructure of a neglected protozoan parasite that is an emerging cause of human disease.
Ellis, JT, Goodswen, SJ, Kennedy, PJ & Bush, SA 2012, 'The Core Mouse Response to Infection by Neospora Caninum Defined by Gene Set Enrichment Analyses', Bioinformatics and Biology Insights, vol. 6, pp. 187-202.View/Download from: Publisher's site
.In this study, the BALB/c and Qs mouse responses to infection by the parasite Neospora caninum were investigated in order to identify host response mechanisms. Investigation was done using gene set (enrichment) analyses of microarray data. GSEA, MANOVA, Romer, subGSE and SAM-GS were used to study the contrasts Neospora strain type, Mouse type (BALB/c and Qs) and time post infection (6 hours post infection and 10 days post infection). The analyses show that the major signal in the core mouse response to infection is from time post infection and can be defined by gene ontology terms Protein Kinase Activity, Cell Proliferation and Transcription Initiation. Several terms linked to signaling, morphogenesis, response and fat metabolism were also identified. At 10 days post infection, genes associated with fatty acid metabolism were identified as up regulated in expression. The value of gene set (enrichment) analyses in the analysis of microarray data is discussed.
Fletcher, S, Stark, DJ, Harkness, JL & Ellis, JT 2012, 'Enteric protozoa in the developed world: A public health perspective', Clinical Microbiology Reviews, vol. 25, no. 3, pp. 420-449.View/Download from: Publisher's site
Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.
Goodswen, SJ, Kennedy, PJ & Ellis, JT 2012, 'Evaluating High-Throughput Ab Initio Gene Finders to Discover Proteins Encoded in Eukaryotic Pathogen Genomes Missed by Laboratory Techniques', PLOS ONE, vol. 7, no. 11.View/Download from: Publisher's site
King, JS, Brown, G, Jenkins, D, Ellis, JT, Fleming, PJ, Windsor, PA & Slapeta, J 2012, 'Oocysts and high seroprevalence of Neospora caninum in dogs living in remote Aboriginal communities and wild dogs in Australia', Veterinary Parasitology, vol. 187, no. 1-2, pp. 85-92.View/Download from: Publisher's site
Canines are definitive hosts of Neospora caninum (Apicomplexa). For horizontal transmission from canines to occur, viable oocysts of N. caninum must occur in the environment of susceptible intermediate hosts. Canids in Australia include wild dogs and Aboriginal community dogs. Wild dogs are those dogs that are not dependent on humans for survival and consist of the dingo, feral domestic dog and their hybrid genotypes. Aboriginal community dogs are dependent on humans, domesticated and owned by a family, but are free-roaming and have free access throughout the community. In this study the extent of N. caninum infection was determined in a total of 374 dogs (75 wild dogs and 299 Aboriginal community dogs) using a combination of microscopic, molecular and serological techniques. Oocysts of N. caninum were observed in the faeces of two juvenile Aboriginal community dogs (2/132; 1.5%). To estimate N. caninum prevalence, a new optimised cut-off of 18.5% inhibition for a commercial competitive ELISA was calculated using a two-graph receiver-operating characteristic (TG-ROC) analysis and IFAT as the gold standard resulting in equal sensitivity and specificity of 67.8%. Of the 263 dog sera tested the true prevalence of N. caninum antibodies was 27.0% (95% confidence limit: 10.3-44.1%). The association between the competitive ELISA results in dogs less than 12 month old and older dogs was significant (P=0.042). To our knowledge this is the first large scale parasitological survey of the Aboriginal community dogs and wild dogs from Australia. The high prevalence of N. canilium infection in Aboriginal community dogs illustrates that horizontal transmission of N. caninum is occurring in Australia. These results demonstrated that N. caninum in dogs is widespread, including the semi-arid to arid regions of north-western New South Wales and the Northern Territory. The populations of free-ranging dogs are likely to be important contributors to the sylvatic life cycle of N. caninu...
Dientamoeba fragilis is an intestinal protozoan in humans that is commonly associated with diarrhoea and other gastrointestinal complaints. Studies conducted to investigate the biology of this parasite are limited by methods for in vitro cultivation. The objective of this study was to improve a biphasic culture medium, based on the Loeffler's slope, by further supplementation in order to increase the yield of trophozoites in culture. The current in vitro culture of D. fragilis is a xenic culture with a mix of bacteria. Three different liquid overlays were evaluated including Earle's balanced salt solution (EBSS), PBS and Dulbecco's modified PBS (DPBS), for their ability to support the in vitro growth of D. fragilis trophozoites. Out of these 3 overlays EBSS gave the highest increase in the trophozoite numbers. The effect of supplementation was analysed by supplementing EBSS with ascorbic acid, ferric ammonium citrate, L-cysteine, cholesterol and alpha-lipoic acid and quantification of in vitro growth by cell counts. A new liquid overlay is here described based upon EBSS supplemented with cholesterol and ferric ammonium citrate that, in conjunction with the Loeffler's slope, supports the growth of D. fragilis trophozoites in vitro. This modified overlay supported a 2-fold increase in the numbers of trophozoite in culture from all 4 D. fragilis isolates tested, when compared to a PBS overlay. These advances enable the harvest of a larger number of trophozoites needed for further studies on this parasite.
Nagata, N, Marriott, DJ, Harkness, JL, Ellis, JT & Stark, DJ 2012, 'Current treatment options for Dientamoeba fragilis infections', International Journal for Parasitology: Drugs and Drug Resistance, vol. 2, pp. 204-215.View/Download from: Publisher's site
Dientamoeba fragilis belongs to the trichomonad group of protozoan parasites and it has been implicated as a cause of gastrointestinal disease with world-wide prevalences ranging from 0.5% to 16%. The majority of patients with dientamoebiasis present with gastrointestinal complaints. Chronic symptoms are common with up to a third of patients exhibiting persistent diarrhoea. Numerous studies have successfully demonstrated parasite clearance, coupled with complete resolution of clinical symptoms following treatment with various antiparasitic compounds. Treatments reported to be successful for dientamoebiasis include carbarsone, diphetarsone, tetracyclines, paromomycin, erythromycin, hydroxyquinolines and the 5-nitroimidazoles, including metronidazole, secnidazole, tinidazole and ornidazole. It is of note that most current treatment data is based only on small number of case reports. No large scale double blind randomised placebo controlled trials testing the efficacy of antimicrobial agents against D. fragilis has been undertaken highlighting the need for further study. In addition there is very little in vitro susceptibility data available for the organism making some current treatment options questionable. The aim of this review is to critically discuss all treatment options currently available for dientamoebiasis.
Nagata, N, Marriott, DJ, Harkness, JL, Ellis, JT & Stark, DJ 2012, 'In vitro susceptibility testing of Dientamoeba fragilis', Antimicrobial agents and chemotherapy, vol. 56, no. 1, pp. 487-494.View/Download from: Publisher's site
Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis, designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2!g/ml to 500!g/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 !g/ml; ronidazole, 8 to 16!g/ml; tinidazole, 31!g/ml; metronidazole, 31!g/ml; secnidazole, 31 to 63!g/ml; nitazoxanide, 63 !g/ml; tetracycline, 250!g/ml; furazolidone, 250 to 500!g/ml; iodoquinol, 500!g/ml; paromomycin, 500!g/ml; and diloxanide furoate,>500!g/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis. Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis.
Stark, DJ, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2012, 'Detection and transmission of Dientamoeba fragilis from environmental and household samples', American Journal of Tropical Medicine and Hygiene, vol. 86, no. 2, pp. 233-236.View/Download from: Publisher's site
Dientamoeba fragilis is a commonly occurring pathogenic protozoan often detected at higher rates in stool samples than Giardia intestinalis. However, little is known about its life cycle and mode of transmission. A total of 210 environmental and household samples were examined for the presence of D. fragilis by culture and polymerase chain reaction. Of 100 environmental samples, D. fragilis was detected only in untreated sewage. In the household samples D. fragilis was detected in 30% of household contacts tested and was not detected in any domestic pets. This study provides evidence that environmental transmission of D. fragilis is unlikely and that pets played no role in transmission of the disease in this study. Direct transmission from infected persons is the most likely mode of transmission for D. fragilis. The study also highlights the need for household contacts to be screened, given the propensity of close contacts to become infected with the organism.
Banik, G, Barratt, JL, Marriott, DJ, Harkness, JL, Ellis, JT & Stark, DJ 2011, 'A case-controlled study of Dientamoeba fragilis infections in children', Parasitology, vol. 138, no. 7, pp. 819-823.View/Download from: Publisher's site
Dientamoeba fragilis is a pathogenic protozoan parasite that is implicated as a cause of human diarrhoea. A case-controlled study was conducted to determine the clinical signs associated with D. fragilis infection in children presenting to a Sydney Hospital. Treatment options are also discussed. Stool specimens were collected from children aged 15 years or younger and analysed for the presence of D. fragilis. In total, 41 children were included in the study along with a control group. Laboratory diagnosis was performed by microscopy of permanently stained, fixed faecal smears and by real-time PCR. Gastrointestinal symptoms were present in 40/41 (98%) of these children with dientamoebiasis, with diarrhoea (71%) and abdominal pain (29%) the most common clinical signs. Chronic gastrointestinal symptoms were present in 2% of cases. The most common anti-microbial used for treatment was metronidazole (n=41), with complete resolution of symptoms and clearance of parasite occurring in 85% of cases. A treatment failure rate occurred in 15% of those treated with metronidazole. Follow-up treatment comprised of an additional course of metronidazole or iodoquinol was needed in order to achieve complete resolution of infection and symptoms in this group. This study demonstrates the pathogenic potential of D. fragilis in children and as such it is recommended that all laboratories must routinely test for this organism and treat if detected.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2011, 'A review of Dientamoeba fragilis carriage in man: Several reasons why this organism should be considered in the diagnosis of gastrointestinal illness', Gut Microbes, vol. 23, no. 1, pp. 1-10.View/Download from: Publisher's site
Dientamoeba fragilis is a protozoan that inhabits the human gut. It is approximately 100 years since Dientamoebas discovery and first description when it was described as a rare and harmless commensal. Since then it has struggled to gain recognition as a pathogen despite the evidence supporting its pathogenicity. Dientamoeba remains neglected, probably due to the misconceptions that it is uncommon and non-pathogenic. Usually, carriage of Dientamoeba is associated with symptoms such as abdominal pain and diarrhea. Moreover, antimicrobial therapy followed by resolution of symptoms coincides with the eradication of Dientamoeba. This manuscript reviews the scientific literature relating to Dientamoebas prevalence and pathogenicity. While much of the evidence supporting its pathogenicity is only circumstantial, it is apparent that most researchers agree that Dientamoeba is pathogenic. Therefore, in symptomatic patients who harbor Dientamoeba and no other pathogen, Dientamoeba should be considered as the etiological agent and treated as such.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2011, 'The ambiguous life of Dientamoeba fragilis: the need to investigate current hypotheses on transmission?', Parasitology, vol. 138, no. 5, pp. 557-572.View/Download from: Publisher's site
Dientamoeba fragilis is an inhabitant of the human bowel and is associated with gastrointestinal illness. Despite its discovery over a century ago, the details of Dientamoebas life cycle are unclear and its mode of transmission is unknown. Several theories exist which attempt to explain how Dientamoeba may be transmitted. One theory suggests that animals are responsible for the transmission of Dientamoeba. However, reports of Dientamoeba in animals are sporadic and most are not supported by molecular evidence. Another theory suggests that Dientamoeba may be transmitted via the ova of a helminth. Given that the closest relative of Dientamoeba is transmitted via the ova of a helminth, this theory seems plausible. It has also been suggested that Dientamoeba could be transmitted directly between humans. This theory also seems plausible given that other relatives of Dientamoeba are transmitted in this way. Despite numerous investigations, Dientamoebas mode of transmission remains unknown. This review discusses the strengths and weaknesses of theories relating to Dientamoebas mode of transmission and, by doing so, indicates where gaps in current knowledge exist. Where information is lacking, suggestions are made as to how future research could improve our knowledge on the life cycle of Dientamoeba.
Fletcher, S, Stark, DJ & Ellis, JT 2011, 'Prevalence of gastrointestinal pathogens in Sub-Saharan Africa: systematic review and meta-analysis', Journal of Public Health in Africa, vol. 2, no. e30, pp. 127-137.
A significant proportion of vulnerable people in sub-Saharan Africa (SSA) remain at risk for contracting diarrhoeal diseases due to the presence of many risk factors facilitating their transmission. A systematic review of published articles from the SSA region was done to determine the prevalence and types of diarrhoeal pathogens in circulation, based on a search of databases, including EBSCO host, PubMed, Scopus, Science Direct, Google scholar and Web of Science was done between September 2009 and December 2010.
King, JS, Jenkins, D, Ellis, JT, Fleming, P, Windsor, PA & Slapeta, J 2011, 'Implications of wild dog ecology on the sylvatic and domestic life cycle of Neospora caninum in Australia', The Veterinary Journal, vol. 188, no. 1, pp. 24-33.View/Download from: Publisher's site
Neospora caninum is transmitted either transplacentally or horizontally by ingestion of tissue cysts present in tissues or oocysts shed by dogs. Neosporosis is a significant disease, causing cattle abortion at 5 7 months of pregnancy. Infected cows may remain infective for life transmitting the infection in several consecutive or non-consecutive pregnancies. A great deal is known about the epidemiology of neosporosis, although only limited information is available on the main routes of horizontal transmission. In Australia, the presence of the dingo as the top-order predator suggests a potential sylvatic route of transmission between dingoes and as yet unknown native wildlife in addition to the domestic route via dogs with access to infected tissue on farms. This review article critically evaluates the overlap between the domestic and sylvatic routes, taking into account canine ecology, and summarises current understanding of the transmission of N. caninum to provide a foundation for epidemiologists, farmers and conservation biologists dealing with neosporosis and wild dog control programs.
King, JS, McAllan, B, Spielman, D, Lindsay, S, Hurkova-Hofmannova, L, Hartigan, A, Al-Qassab, SE, Ellis, JT & Slapeta, J 2011, 'Extensive production of Neospora caninum tissue cysts in a carnivorous marsupial succumbing to experimental neosporosis', Veterinary Research, vol. 42, no. 1, pp. 75-84.View/Download from: Publisher's site
Experimental infections of Sminthopsis crassicaudata, the fat-tailed dunnart, a carnivorous marsupial widely distributed throughout the arid and semi-arid zones of Australia, show that this species can act as an intermediate host for Neospora caninum. In contrast to existing models that develop relatively few N. caninum tissue cysts, dunnarts offer a new animal model in which active neosporosis is dominated by tissue cyst production. The results provide evidence for a sylvatic life cycle of N. caninum in Australia between marsupials and wild dogs. It establishes the foundation for an investigation of the impact and costs of neosporosis to wildlife.
Roberts, TJ, Barratt, JL, Harkness, JL, Ellis, JT & Stark, DJ 2011, 'Comparison of Microscopy, Culture, and Conventional Polymerase Chain Reaction for Detection of Blastocystis sp. in Clinical Stool Samples.', American Journal of Tropical Medicine and Hygiene, vol. 84, no. 2S, pp. 308-312.View/Download from: Publisher's site
We tested 513 stool samples from patients in Sydney, Australia for Blastocystis by using five diagnostic techniques: microscopy of a permanently stained smear using a modified iron-hematoxylin stain, two xenic culture systems (a modified Boeck and Drbohlav's medium and tryptone, yeast extract, glucose, methionine-9 medium), and two published conventional polymerase chain reaction methods specific for the small subunit ribosomal DNA. Ninety-eight (19%) samples were positive for Blastocystis in one or more of the diagnostic techniques. The PCR 2 method was the most sensitive at detecting Blastocystis with a sensitivity of 94%, and the least sensitive was microscopy of the permanent stain (48%). Subtype 3 was the most predominant subtype (present in 43% of samples assigned to this group). This study highlights the low sensitivity of microscopy when used as the sole diagnostic modality for detection of Blastocystis sp
Stark, DJ, Al-Qassab, SE, Barratt, JL, Stanley, K, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2011, 'Evaluation of Multiplex Tandem Real-Time PCR for Detection of Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis in Clinical Stool Samples', Journal Of Clinical Microbiology, vol. 49, no. 1, pp. 257-262.View/Download from: Publisher's site
The aim of this study was to describe the first development and evaluation of a multiplex tandem PCR (MT-PCR) assay for the detection and identification of 4 common pathogenic protozoan parasites; Cryptosporidium spp., Dientamoeba fragilis, Entamoeba histolytica, and Giardia intestinalis from human clinical samples. A total of 472 faecal samples submitted to the Department of Microbiology at St. Vincent's Hospital were included in the study. The MT-PCR assay was compared to four real-time PCR assays (RT-PCR) and microscopy by a traditional modified iron haematoxylin stain. The MT-PCR detected 28 G. intestinalis, 26 D. fragilis, 11 E. histolytica, and 9 Cryptosporidium spp. isolates. Detection and identification of the faecal protozoa by MT-PCR demonstrated 100% correlation with the RT-PCR results and when compared to RT-PCR the MT-PCR exhibited 100% sensitivity and specificity, while traditional microscopy of stained fixed faecal smears exhibited sensitivities and specificities of 56% and 100% for Cryptosporidium ssp., 38% and 99% for D. fragilis, 47% and 97% for E. histolytica and 50% and 100% for G. intestinalis respectively. No cross reactivity was detected in 100 stool samples containing various other bacterial, viral and protozoan species. The MT-PCR assay was able to provide rapid, sensitive and specific simultaneous detection and identification of the four most important diarrhoea causing protozoan parasites that infect humans. This study also highlights the lack of sensitivity demonstrated by microscopy and as such molecular methods such as MT-PCR must be considered the diagnostic method of choice for enteric protozoan parasites.
Neospora caninum is a parasite regarded a major cause of foetal loss in cattle. A key requirement to an understanding of the epidemiology and pathogenicity of N caninum is knowledge of the biological characteristics of the species and the genetic diversity within it. Due to the broad intermediate host range of the species, worldwide geographical distribution and its capacity fQr sexual reproduction, significant biological and genetic differences might be expected to exist. N caninum has now been isolated from a variety of different host species including dogs and cattle. Although isolates of this parasite show only minor differences in ultrastructure, considerable differences have been reported in pathogenicity using mainly mouse models. At the DNA level, marked levels of polymorphism between isolates were detected in mini- and microsatellites found in the genome of N caninum. Knowledge of what drives the biological differences that have been observed between the various isolates at the molecular level is crucial in aiding our understanding of the epidemiology of this parasite and, in tum, the development of efficacious strategies, such as live vaccines, for controlling its impact. The purpose of this review is to document and discuss for the first time, the nature of the diversity found within the species Neospora caninum.
Barratt, JL, Banik, G, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2010, 'Newly defined conditions for the in vitro cultivation and cryopreservation of Dientamoeba fragilis: new techniques set to fast track molecular studies on this organism', Parasitology, vol. 137, no. 13, pp. 1867-1878.View/Download from: Publisher's site
Dientamoeba fragilis is a pathogen of the human gastrointestinal tract that is a common cause of diarrhoea. A paucity of knowledge on the in vitro cultivation and cryopreservation of Dientamoeba has meant that few studies have been conducted to investigate its biology. The objective of this study was to define, for the first time, in vitro culture conditions able to support the long-term in vitro growth of Dientamoeba. Also, we aimed to define a suitable method for cryopreserving viable Dientamoeba trophozoites. A modified BD medium, TYGM-9, Loeffler's slope medium, Robinson's medium, Medium 199, Trichosel and a Tritrichomonas fetus medium were compared, using cell counts, for their ability to support the growth of D. fragilis at various temperatures and atmospheric conditions. Loeffler's slope medium supported significantly better growth compared to other media. A temperature of 42°C and a microaerophilic atmosphere were also optimum for Dientamoeba growth. To our knowledge, this is the first study to describe and compare different culture media and conditions for the growth of clinical isolates of D. fragilis. This new technology will aid the development of diagnostics for dientamoebiasis as well as facilitate large-scale sequencing projects that will fast track molecular studies on D. fragilis.
Barratt, JL, Harkness, JL, Marriott, DJ, Ellis, JT & Stark, DJ 2010, 'The Importance of Non-enteric Protozoan Infections in Immunocompromised Patients', Clinical Microbiology Reviews, vol. 23, no. 4, pp. 795-836.View/Download from: Publisher's site
There are many neglected nonenteric protozoa able to cause serious morbidity and mortality in humans, particularly in the developing world. Diseases caused by certain protozoa are often more severe in the presence of HIV. While information regarding neglected tropical diseases caused by trypanosomatids and Plasmodium is abundant, these protozoa are often not a first consideration in Western countries where they are not endemic. As such, diagnostics may not be available in these regions. Due to global travel and immigration, this has become an increasing problem. Inversely, in certain parts of the world (particularly sub-Saharan Africa), the HIV problem is so severe that diseases like microsporidiosis and toxoplasmosis are common. In Western countries, due to the availability of highly active antiretroviral therapy (HAART), these diseases are infrequently encountered. While free-living amoebae are rarely encountered in a clinical setting, when infections do occur, they are often fatal. Rapid diagnosis and treatment are essential to the survival of patients infected with these organisms. This paper reviews information on the diagnosis and treatment of nonenteric protozoal diseases in immunocompromised people, with a focus on patients infected with HIV. The nonenteric microsporidia, some trypanosomatids, Toxoplasma spp., Neospora spp., some free-living amoebae, Plasmodium spp., and Babesia spp. are discussed.
Bishop, S, King, JS, Windsor, PA, Reichel, MP, Ellis, JT & Slapeta, J 2010, 'The first report of ovine cerebral neosporosis and evaluation of Neospora caninum prevalence in sheep in New South Wales', Veterinary Parasitology, vol. 170, no. 1-2, pp. 137-142.View/Download from: Publisher's site
Presence of Neospora caninum DNA was detected in the brain and spinal cord of an adult Merino sheep suspected of dying with acute non-suppurative meningoencephalitis and mild to moderate non-suppurative myelitis. The most severe neurological lesions were found in the midbrain at the rostral coliculi with moderate to severe multifocal vasculitis and gliosis. As this was the first known occurrence of cerebral disease in sheep in Australia caused by N. caninum, we surveyed sera from five sheep properties in New South Wales (NSW) to obtain information on the likely prevalence of N. caninum infection in NSW sheep flocks. Serology using a commercial indirect enzyme-linked immunosorbent assay (ELISA) revealed no N. caninum antibody-positive sheep (n = 184). However an observed prevalence for N. caninum antibodies using a commercially available competitive ELISA was 2.2% (5/232). We conclude that although the diagnosis of fatal ovine cerebral neosporosis is of importance to our surveillance program for transmissible spongiform encephalopathy (TSE) exclusion, sheep in NSW are not commonly infected with N. caninum and this species likely plays only a minor role in the life cycle of this parasite in Australia.
Ellis, JT, Sinclair, D, Morrison, DJ, Al-Qassab, SE, Springett, K & Ivens, A 2010, 'Microarray analyses of mouse responses to infection by Neospora caninum identifies disease associated cellular pathways in the host response', Molecular & Biomedical Parasitology, vol. 174, no. 2, pp. 117-127.View/Download from: Publisher's site
Neospora caninum is a coccidian cyst-forming parasite found in a wide range of host species such as mice, dogs and cattle. The development of methods such as vaccines to prevent abortion and fetal loss due to neosporosis would be greatly assisted by further knowledge on immunity and host responses to infection. In this study we used microarray technology to investigate the protective host responses occurring at 6 h post infection in the spleen of mice infected with a prototype live N. caninum vaccine. Naive non-pregnant mice were infected with the NC-Nowra isolate as such infections are known to induce protective host responses that will prevent transplacental transmission of a challenge given using pregnancy. The expression data was analysed by SAM (significance of microarrays), ANOVA and clustering methods. Gene lists were investigated for enrichment of gene ontology terms by functional annotation using hypergeometric tests. The results show that Qs and BALB/c mice infected with NC-Nowra differ in their transcriptional responses to infection and these affect a wide range of biological and molecular processes. Transcriptional changes in the Jak-STAT signaling pathway (as well as Irf and other IFN-? regulated molecules such as GTPases) confirmed the influence of IFN-? in the mouse response to N. caninum. Gene ontology analyses also assigned some of the molecules involved to well known disease pathways associated with cancer, Parkinson's and Alzheimer's diseases, which were linked to the cell cycle, mitochondrial electron transport chain and coupled proton transport pathways amongst others. Although infection of mice with NC-Nowra causes little or no signs of clinical disease, the molecular functions, processes and pathways identified through these studies clearly warrant further investigation for their role in the development of protective immunity as well as pathogenesis. These studies therefore provide new, exciting leads by which to study neosporosis.
King, JS, Slapeta, J, Jenkins, D, Al-Qassab, SE, Ellis, JT & Windsor, PA 2010, 'Australian dingoes are definitive hosts of Neospora caninum', International Journal For Parasitology, vol. 40, no. 8, pp. 945-950.View/Download from: Publisher's site
To provide objective data on the potential role of dingoes (Canis lupus dingo) in the life cycle of Neospora caninum in Australia, the production of N. caninum oocysts by experimentaIly infected canids was inves~ tigated. Three dingo pups raised in captivity and three domestic dogs were fed tissue from calves infected with an Australian isolate of N. cuninum. Nc-Nowra. Oocysts of N. caninum. confirmed by species-specific PCR. were shed in low numbers by one dingo pup at 12-14 days p.i. The remaining animals did not shed oocysts. Furthermore. the blood from two out of three dingoes tested positive for DNA of N. caninum using PCR tests at 14 and 28 days poi. Oocyst shedding from the intestinal tract of a dingo demonstrates that dingoes are definitive hosts of N. caninum and horizontal transmission of N. coninum from dingoes to farm animals and wildlife may occur in Australia
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2010, 'A review of the clinical presentation of dientamoebiasis', American Journal Of Tropical Medicine And Hygiene, vol. 82, no. 4, pp. 614-619.View/Download from: Publisher's site
Among 750 symptomatic and asymptomatic patients, Dientamoeba fragilis was detected at a prevalence of 5.2% and more common than Giardia intestinalis. Most infected patients presented with diarrhea and abdominal pain with symptoms greater than 2 weeks duration being common. Bacterial and viral causes of infection were excluded by routine microbiological techniques. Treatment of D. fragilis infection with either iodoquinol, paromomycin, or combination therapy resulted in the eradication of the parasite and complete resolution of symptoms. Treatment failure/relapses were associated only with the use of metronidazole. Nineteen patients were examined for pin worm, no Enterobius vermicularis, a proposed vector of transmission, were detected. Intermittent shedding of D. fragilis was found to be highly variable. These studies confirm the pathogenic nature of D. fragilis and we recommend laboratories routinely test for the organism.
Stark, DJ, Barratt, JL, Roberts, TJ, Marriott, DJ, Harkness, JL & Ellis, JT 2010, 'Comparison of microscopy, two xenic culture techniques, conventional and real-time PCR for the detection of Dientamoeba fragilis in clinical stool samples.', European Journal of Clinical Microbiology & Infectious Diseases, vol. 29, no. 4, pp. 411-416.View/Download from: Publisher's site
Dientamoeba fragilis is a pathogenic protozoan parasite that is notoriously difficult to diagnose. The aim of this study was to detennine the gold standard for laboratory detection of D. fragilis. A total of 650 human faecal samples were included in the study. All specimens underwent the following: microscopy using a pennanent stain (modified iron-haematoxylin), culture using a modified Boeck and Drbohlav's medium (MBD) and TYGM-9, a conventional polymerase chain reaction (peR) and a realtime PCR (RT-PCR). The overall prevalence of D. fragilis in the study population was 5.4% (35/650). RT-PCR detected 35 isolates, conventional PCR detected 15 isolates, MBD culture detected 14 isolates, TYGM-9 detected ten isolates, while microscopy' detected 12 isolates. RT-PCR detected an additional 15 positive samples compared to the other diagnostic methods, all of which were confinned by sequencing. When all methods were compared to each other, RT-PCR showed a sensitivity and specificity of 100 and 100%, conventional POR 42.9 and 100%, MBD culture 40 and 100%, TYGM-9 culture 28.6 and 100%, and microscopy 34.3 and 99%, respectively. These results show that RT-PCR is the diagnostic method of choice for the detection of D. fragilis in clinical samples and, as such, should be considered as the gold standard for diagnosis.
Al-Qassab, SE, Reichel, MP & Ellis, JT 2009, 'A second generation multiplex PCR for typing strains of Neospora caninum using six DNA targets', Molecular and Cellular Probes, vol. 24, no. 1, pp. 20-26.View/Download from: Publisher's site
Genetic diversity of Neospora caninum was investigated through a study of repetitive sequences found in the genome of this species. Twenty different loci were studied, and three were identified that varied in repeat content amongst isolates. No relationship was found between the copy number of repetitive sequences present and host type or geographical location from which the isolates were derived. A multiplex PCR assay was developed for multilocus-strain typing using three microsatellites and three minisatellites, based on the polymorphisms found in the repetitive sequences. This study therefore extends knowledge on the repetitive sequences found in the N. caninum genome and the diversity found within the species. It also provides a second generation multiplex assay that can be used to study the biology of N. caninum. In addition, this study included Neospora hughesi (along with other closely related apicomplexans) as controls. The present study shows N. hughesi to be quite distinct from N. caninum in these repetitive sequences, thereby potentially providing a new approach for the differentiation of these two taxa.
Al-Qassab, SE, Reichel, MP, Ivens, A & Ellis, JT 2009, 'Genetic Diversity Amongst Isolates Of Neospora Caninum, And The Development Of A Multiplex Assay For The Detection Of Distinct Strains', Molecular & Cellular Probes, vol. 23, no. 3-4, pp. 132-139.View/Download from: Publisher's site
Infection with Neospora caninum is regarded as a significant cause of abortion in cattle. Despite the economic impact of this infection, relatively little is known about the biology of this parasite. In this study, mini and microsatellite DNAs were detec
Al-Qassab, SE, Reichel, MP, Su, C, Jenkins, D, Hall, C, Windsor, PA, Dubey, J & Ellis, JT 2009, 'Isolation of Toxoplasma gondii from the brain of a dog in Australia and its biological and molecular characterization', Veterinary Parasitology, vol. 164, no. 2-4, pp. 335-339.View/Download from: Publisher's site
Toxoplasma gondii was isolated from the brain of a young dog for the ?rst time in Australia. The identity of the parasite was con?rmed by PCR, Western blotting, electron microscopy and cat bioassay. Genotyping of the isolate (TgDgAu1) was determined by PCR-RFLP markers that showed it to be a Type II strain. Western blotting demonstrated the presence of IgM antibodies to T. gondii suggesting the bitch was probably infected during pregnancy and the T. gondii was transmitted to the pups congenitally. We believe this represents the ?rst description of a natural case of congenital transmission of T. gondii in the dog
Fry, D, Mcsporran, K, Ellis, JT & Harvey, C 2009, 'Protozoal Hepatitis Associated With Immunosuppressive Therapy In A Dog', Journal Of Veterinary Internal Medicine, vol. 23, no. 2, pp. 366-368.View/Download from: Publisher's site
Reichel, MP & Ellis, JT 2009, 'Neospora caninum--how close are we to development of an efficacious vaccine that prevents abortion in cattle?', International Journal For Parasitology, vol. 39, no. 11, pp. 1173-1187.View/Download from: Publisher's site
Neospora caninum is a protozoan parasite that causes abortion in cattle around the world. Although the clinical signs of disease in both dogs and cattle have now been recognised for over 20 years, treatment and control options are still limited, despite the availability of a commercial vaccine in some countries of the world. The case for an efficacious vaccine has not been convincingly waged by farmers, veterinarians and other members of the agricultural and rural communities. In recent times, however, economic modelling has been used to estimate the industry losses due to Neospora-associated abortion, providing, in turn, the business case for forms of control for this parasite, including the development of vaccines. In this review, we document progress in all areas of the vaccine development pipeline, including live, killed and recombinant forms and the animal models available for vaccine evaluation. In addition, we summarise the main outcomes on the economics of Neospora control and suggest that the current boom in the global dairy industry increases the specific need for a vaccine against N. caninum-associated abortion.
Sotirchos, IM, Hudson, AL, Ellis, JT & Davey, MW 2009, 'A unique thioredoxin of the parasitic nematode Haemonchus contortus with glutaredoxin activity', Free Radical Biology and Medicine, vol. 46, no. 5, pp. 579-585.View/Download from: Publisher's site
The dependency of parasites on the cellular redox systems has led to their investigation as novel drug targets. Defence against oxidative damage is through the thioredoxin and glutathione systems. The classic thioredoxin is identified by the active site Cys-Gly-Pro-Cys (CGPC). Here we describe the identification of a unique thioredoxin in the parasitic nematode, Haemonchus contortus. This thioredoxin-related protein, termed HcTrx5, has an arginine in its active site (Cys-Arg-Ser-Cys; CRSC) that is not found in any other organism. Recombinant HcTrx5 was able to reduce the disulfide bond in insulin, and be regenerated by mammalian thioredoxin reductase with a Km 2.19 ± 1.5 µM, similar to the classic thioredoxins. However, it was also able to reduce insulin when glutathione and glutathione reductase replaced the thioredoxin reductase. When coupled with H. contortus peroxiredoxin, HcTrx5 was active using either the thioredoxin reductase or the glutathione and glutathione reductase. HcTrx5 is expressed through the life cycle, with highest expression in the adult stage. The unique activity of this thioredoxin makes it a potential drug target for the control of this parasite.
Stark, DJ, Barratt, JL, Ellis, JT, Harkness, JL & Marriott, DJ 2009, 'Repeated Dientamoeba fragilis infections: a case report of two families from Sydney, Australia', Infectious Disease Reports, vol. 1, no. e4, pp. 7-9.View/Download from: Publisher's site
We report cases of two unrelated families who both presented with recurrent Dientamoeba fragilis infections. Subsequent antimicrobial therapy resulted in the clearance of D. fragilis and total resolution of gastrointestinal symptoms in both families. This report highlights the potentially recurrent nature of D. fragilis infections and the need for laboratories to routinely test for this organism.
Stark, DJ, Barratt, JL, Van Hal, SJ, Marriott, DJ, Harkness, JL & Ellis, JT 2009, 'Clinical significance of enteric protozoa in the immunosuppressed human population', Clinical Microbiology Reviews, vol. 22, no. 4, pp. 634-650.View/Download from: Publisher's site
Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4+ cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.
Stark, DJ, Van Hal, SJ, Barratt, JL, Ellis, JT, Marriott, DJ & Harkness, JL 2009, 'Limited genetic diversity among genotypes of Enterocytozoon bieneusi strains Isolated from HIV-Infected patients from Sydney, Australia', Journal of Medical Microbiology, vol. 58, no. 3, pp. 355-357.View/Download from: Publisher's site
Microsporidia are intracellular parasites, with over 1200 species belonging to 143 genera described to date. They are opportunistic pathogens in humans and can cause chronic diarrhoea in immunosuppressed patients. Both Enterocytozoon bieneusi and Encephalitozoon intestinalis cause intestinal disease, with Enterocytozoon bieneusi more commonly identified in patients with human immunodeficiency virus (HIV) infection. In this study, intestinal microsporidial clinical isolates from patients in Sydney, Australia, were genotyped. All specimens were from HIV-infected men with low CD4(+) T-cell counts (<100 cells mm(-3)). Genotyping of the internal transcribed spacer regions of the rRNA gene showed the presence of only one genotype, the anthroponotic Enterocytozoon bieneusi genotype B strain. This study thus highlighted the limited genetic diversity among Australian Enterocytozoon bieneusi isolates, and it is hypothesized that, due to the reduced incidence of microsporidia. and the subsequent reduction in the human reservoir of the anthroponotic genotype B, locally acquired intestinal microsporidiosis will rarely be seen in HIV-infected persons undergoing highly active antiretroviral therapy in the future in Australia.
Barratt, JL, Al-Qassab, SE, Reichel, MP & Ellis, JT 2008, 'The development and evaluation of a nested PCR assay for detection of Neospora caninum and Hammondia heydorni in feral mouse tissues', Molecular & Cellular Probes, vol. 22, no. 4, pp. 228-233.View/Download from: Publisher's site
The development of a novel nested polymerase chain reaction is desribed and used for detecting the presence of Neospora caninum and Hammondai heydorni DNA in DNA extracted from feral rodent tissues.
Ellis, JT, Miller, CM, Quinn, HE, Ryce, C & Reichel, MP 2008, 'Evaluation of recombinant proteins of Neospora caninum as vaccine candidates (in a mouse model)', Vaccine, vol. 26, no. 47, pp. 5989-5996.View/Download from: Publisher's site
Abortion resulting from infections by the parasite Neospora caninum is a mojor cause of economic loss to both the dairy and beef industries of cattle-producing countries of the world. Vaccination as a means of preventing abortion and/or infection represents a viable control strategy; indeed a commercial vaccine is available in some countries, albeit of unlnown efficacy.
Fotedar, R, Stark, DJ, Marriott, DJ, Ellis, JT & Harkness, JL 2008, 'Entamoeba moshkovskii infections in Sydney, Australia', European Journal of Clinical Microbiology & Infectious Diseases, vol. 27, no. 2, pp. 133-137.View/Download from: Publisher's site
Entamoeba moshkovskii is considered to be a free-living ameba which is morphologically similar, but biochemically and genetically different to Entamoeba histolyticca and Entamoeba dispar. However recent studies have suggested that E. moshkovskii may be a "potential" pathogen with infections giving rise to diarrhea and toehr intetinal disorders.
Reichel, MP & Ellis, JT 2008, 'Re-evaluating the economics of neosporosis control', Veterinary Parasitology, vol. 156, pp. 361-362.
Sotirchos, IM, Hudson, AL, Ellis, JT & Davey, MW 2008, 'Thioredoxins of a parasitic nematode: Comparison of the 16- and 12-kDA thioredoxins from Haemonchus contortus', Free Radical Biology And Medicine, vol. 44, no. 12, pp. 2026-2033.View/Download from: Publisher's site
Thioredoxins are a family of small proteins conserved through evolution, which are essential for the maintenance of cellular homeostasis. The classic thioredoxin, identified in most species, is a 12-kDa protein with a Cys-Pro-Gly-Cys (CPGC) active site.
Stark, DJ, Phillips, O, Peckett, D, Munro, UH, Marriott, DJ, Harkness, JL & Ellis, JT 2008, 'Gorillas are a host for Dientamoeba fragilis: an update on the life cycle and host distribution', Veterinary Parasitology, vol. 151, no. 1, pp. 21-26.View/Download from: Publisher's site
Dientamoeba fragilis is a gastrointestinal protozoan that has a workldwide distribution and is emerging as a common caise of diarrhea. As D. fragilis has a propensity to cause chronic illness with symptoms similar to irritable bowel syndrome (IBS) it is not surprising that some patients with D. fragilis are misidagnosed as having IBS. In contrast to mosrt other pethogenic protozoa verylittle is known about its life ycle, epidemiology and mode of transmission. What role animal reservoirs play in the transmission pf this parasite s unknown.
Stark, DJ, Van Hal, SJ, Fotedar, R, Butcher, A, Marriott, DJ, Ellis, JT & Harkness, JL 2008, 'Comparison of stool antigen detection kits to PCR for diagnosis of amebiasis', Journal Of Clinical Microbiology, vol. 46, no. 5, pp. 1678-1681.View/Download from: Publisher's site
The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of Entamoeba histolytica infections by using fecal specimens submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, and the Ins
Fotedar, R, Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'Laboratory diagnostic techniques for Entamoeba species', Clinical Microbiology Reviews, vol. 20, no. 3, pp. 511-532.View/Download from: Publisher's site
The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli and Entamoeba hartmanni) reside in the human intestinal lumen. Entmoeba histolytica is the onl species definitely associated with pathological sequelae in humnas; the others are considered non-pathogenic (31,57). Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms (52, 73, 130, 189, 201), there is sitll no definitive evidence of a causa link between the presence of these two species and the symptoms of the host.
Fotedar, R, Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'PCR Detection of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in Stool Samples from Sydney, Australia', Journal Of Clinical Microbiology, vol. 45, no. 3, pp. 1035-1037.View/Download from: Publisher's site
This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.
The dog is a definitive host of the protozoan parasite Neospora caninum, and in many parts of the world, infection is relatively common as determined by serology. Reported seroprevalences usually range from 0 to 20 per cent, however, reports of clinically affected dogs are infrequent. Affected dogs are generally less than six months old and predominantly have signs of an ascending hindleg paralysis, with the associated lesions of polyradiculoneuritis and granulomatous polymyositis. Although any organ may be affected, infections are more common in the central nervous system, muscles, lungs and skin. Ante-mortem diagnosis is difficult but serology and cytology can aid diagnosis. The diagnosis can be confirmed by histology, immunohistochemistry, the use of molecular techniques on biopsy material, or on post-mortem examination. Neospora caninum oocysts are rarely found in faeces and must be differentiated from oocysts of related coccidians such as Hammondia heydorni and Toxoplasma gondii. Hammondia heydorni can cause diarrrhoea in immunosuppressed dogs. Neosporosis should be suspected in young pups with an ascending paralysis of the hindlegs. Treatment with clindamycin and potentiated sulphonamides may be useful in cases where muscular atrophy and fibrosis are absent. Feeding of raw meat is a potential risk factor for infection of dogs and should be discouraged.
Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'Dientamoeba fragilis as a Cause of Travelers' Diarrhea: Report of Seven Cases', Journal of Travel Medicine, vol. 14, no. 1, pp. 72-73.
Dientamoeba fragilis is a pathogenic trichomonad parasite that causes gastrointestinal disease in humans. We report seven cases of travelers' diarrhea caused by D fragilis in patients who had traveled to overseas destinations within Asia or the Pacific which occurred over an 8-month period. Patients presented with diarrhea lasting from 5 days to over 4 weeks. Dientamoeba fragilis should be considered as a cause of diarrhea in returning travelers.
Stark, DJ, Fotedar, R, Van Hal, SJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'Prevalence of enteric protozoa in Human ImmunoDeficiency Virus (HIV)-positive and HIV negative men who have sex with men from Sydney, Australia', American Journal of Tropical Medicine and Hygiene, vol. 76, no. 3, pp. 549-552.
A prospective, comparative study of the prevalence of enteric protozoa was determined among human immunodeficiency virus (HIV)â positive and HIV-negative men who have sex with men (MSM) in Sydney, Australia. A total of 1,868 patients submitted stool specimens; 1,246 were from MSM (628 HIV positive and 618 HIV positive) and 622 from non-MSM were examined over a 36-month period. A total of 651 (52.2%) stool specimens from MSM were positive for protozoa compared with 85 (13%) from non-MSM. There was a significant difference in the prevalence of Blastocystis hominis, Endolimax nana, Entamoeba histolytica/dispar complex, Entamoeba hartmanni, Iodamoeba butschlii, and Enteromonas hominis detected between MSM and non-MSM (P < 0.001). The only notable difference between HIV-negative and HIV-positive MSM was that HIV-infected MSM were found to more likely have a Cryptosporidium parvum infection. Entamoeba histolytica was found in 3 patients, E. dispar in 25, and E. moshkovskii in 17, all of whom were MSM. When compared with a control group, MSM were significantly more likely to harbor intestinal protozoa and have multiple parasites present. The results of this study show high rates of enteric parasites persist in MSM and highlight the importance of testing for intestinal parasites in MSM. This is the first report of E. moshkovskii from MSM.
Stark, DJ, Van Hal, SJ, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'Irritable bowel syndrome: A review on the role of intestinal protozoa and the importance of their detection and diagnosis', International Journal For Parasitology, vol. 37, no. 1, pp. 11-20.View/Download from: Publisher's site
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder in which abdominal pain is associated with a defect or a change in bowel habits. Gut inflammation is one of the proposed mechanisms of pathogenesis. Recent studies have described a possible role for protozoan parasites, such as Blastocystis hominis and Dientamoeba fragilis, in the etiology of IBS. Dientamoeba fragilis is known to cause IBS-like symptoms and has a propensity to cause chronic infections but its diagnosis relies on microscopy of stained smears, which many laboratories do not perform, thereby leading to the misdiagnosis of dientamoebiasis as IBS. The role of B. hominis as an etiological agent of IBS is inconclusive, due to contradictory reports and the controversial nature of B. hominis as a human pathogen. Although Entamoeba histolytica infections occur predominately in developing regions of the world, clinical diagnosis of amebiasis is often difficult because symptoms of patients with IBS may closely mimic those patients with non-dysenteric amoebic colitis. Clinical manifestations of Giardia intestinalis infection also vary from asymptomatic carriage to acute and chronic diarrhoea with abdominal pain. These IBS-like symptoms can be continuous, intermittent, sporadic or recurrent, sometimes lasting years without correct diagnosis. It is essential that all patients with IBS undergo routine parasitological investigations in order to rule out the presence of protozoan parasites as the causative agents of the clinical signs.
Van Hal, SJ, Stark, DJ, Fotedar, R, Marriott, DJ, Ellis, JT & Harkness, JL 2007, 'Amoebiasis: current status in Australia', Medical Journal of Australia, vol. 186, no. 8, pp. 412-416.
Entamoeba histolytica is one of the most common parasitic infections worldwide, infecting about 50 million people and resulting in 40 000â100 000 deaths a year. In Australia, people at risk of infection include immigrants, travellers returning from countries of high endemicity, Indigenous people, and men who have sex with men. Clinical manifestations range from asymptomatic carriage to invasive disease. Amoebic colitis and amoebic liver abscess are the most common invasive manifestations observed in Australia. Diagnosis depends on a high index of suspicion and laboratory investigations. Molecular methods (using the polymerase chain reaction) are the most sensitive for identifying and differentiating Entamoeba species. Treatment should always include a luminal agent to eradicate colonisation, prevent spread and/or reduce the risk of invasive disease. Medical therapy can successfully cure invasive disease, including amoebic liver abscesses.
Williams, DJ, Guy, C, Smith, RF, Ellis, JT, Bjorkmann, C, Reichel, MP & Trees, SJ 2007, 'Immunization of cattle with live tachyzoites of Neospora caninum confers protection against fetal death', Infection And Immunity, vol. 75, no. 3, pp. 1343-1348.View/Download from: Publisher's site
Neospora caninum is an obligate intracellular protozoan parasite that causes abortion in cattle. It is normally found as a latent infection controlled by a T-helper-cell type 1 response involving CD4 cytotoxic T cells and gamma interferon. Cattle may be infected by two different routes: transplacentally as a result of activation of the latent infection in the mother causing congenital infection or abortion and by ingestion of oocysts, which, if it occurs during gestation, can also result in abortion. Here, for the first time, we establish proof that live vaccination protects against fetal death, whereas immunization using whole-tachyzoite lysate in different adjuvants fails to protect against fetal death. Strong antibody responses were induced in all the vaccinated groups, and the quality and magnitude of these responses were similar in the live- and the lysate-vaccinated groups. In contrast, only the group immunized with live tachyzoites had strong cellular and gamma interferon responses prior to challenge, and these responses correlated with protection against fetopathy. These results suggest that a cellular immune response may be important in the mechanisms involved in protection against N. caninum-associated abortions.
Abel, J, Schares, G, Orzeszko, K, Gasser, RB & Ellis, JT 2006, 'Hammondia isolated from dogs and foxes are genetically distinct', Parasitology, vol. 132, no. 1, pp. 187-192.View/Download from: Publisher's site
Hammondia heydorni is regarded as a protozoan parasite that uses canids, e.g. dogs and foxes, as definitive hosts, but clinical signs of infection are rare. This study therefore took advantage of the opportunity to study an oocyst population from the fae
Hall, C, Reichel, MP & Ellis, JT 2006, 'Performance characteristics and optimisation of cut-off values of two enzyme-linked immunosorbent assays for the detection of antibodies to Neospora caninum in the serum of cattle', Veterinary Parasitology, vol. 140, no. 1-2, pp. 61-68.View/Download from: Publisher's site
Aim: To determine the performance characteristics of two enzyme-linked immunosorbent assays (ELISAs) manufactured by Institut Pourquier (IP) for the detection of antibodies against Neospora caninum in bovine sera. Methods: Sera from 526 cattle were assay
Hall, C, Reichel, MP & Ellis, JT 2006, 'Prevalence of neospora caninum infection in Australian (NSW) dairy cattle estimated by a newly validated ELISA for milk', Veterinary Parasitology, vol. 142, no. 1-2, pp. 173-178.View/Download from: Publisher's site
Aim: To determine the performance characteristics of an Institut Pourquier (IP) enzyme-linked immunosorbent assay (ELISA) for the detection of antobodies against Neospora caninum in bovine milk and subsequent determination of the prevalence of N. caninum infection in NSW dairy cattle. Conclusions: The prevalence of N.caninum in NSW dairy cattle was higher than previously believed. When used on individual milk samples this ELISA demonstrated high sensitivity and specificty and so could be used to accuratley identify N. caninum infection. TG-ROC analysis of the IP ELISA optimised the protocol and prescribed cut-off values enabling the ELISA to be used for the screening of N. caninum antibodies in the milk of dairy cattle.
Reichel, MP & Ellis, JT 2006, 'If control of Neospora caninum infection is technically feasible does it make economic sense?', Veterinary Parasitology, vol. 142, pp. 23-34.View/Download from: Publisher's site
Recent work on Neospora caninum, a protozoan parasite that causes abortion in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were contruscted to choose between four different control strategies. The costs of these interventions, such as 'test and cull', therapeutic treatment with a pharmaceutical, vaccination or "doing nothing" were compared, and modelled, in the first instacne on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in toehr countries might be similar and that only teh availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To "do nothing" emerged as the optimal economic choice for n. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 year horizon.
Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2006, 'Dientamoebiasis: clinical importance and recent advances', Trends in Parasitology, vol. 22, no. 2, pp. 92-96.View/Download from: Publisher's site
Dientamoeba fragilis, an unusual single-celled parasite that was described first in 1918, is found worldwide in the gastrointestinal tract of humans. D. fragilis has emerged from obscurity recently because it is now recognised as a common cause of chronic diarrhoea abd is treatable with drugs. Recent molecular studies have described D. fragilis as having two genotypes. Diagnostic tests, based on conventional and real-time PCR, have been developed that will provide a rapid, sensitive and specific diagnosis of D. fragilis. These tests willalso aid the elucidation of the host distribution and the life cycle of this pathogen.
Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2006, 'Evaluation of three diagnostic methods, including real-time PCR, for detection of Dientamoeba fragilis in stool specimens', Journal Of Clinical Microbiology, vol. 44, no. 1, pp. 232-235.View/Download from: Publisher's site
Dientamoeba fragilis is a protozoan parasite of humans that infects the mucosa of the large intestine and is associated with gastrointestinal disease. We developed a 5 nuclease (TaqMan)-based real-time PCR assay, targeting the small subunit rRNA gene, fo
Stark, DJ, Fotedar, R, Ellis, JT & Harkness, JL 2006, 'Locally acquired infection with Entamoeba histolytica in men who have sex with men in Australia', The Medical Journal of Australia, vol. 185, no. 8, pp. 417-417.
To the Editor: We report three cases of locally acquired Entamoeba histolytica infection in men who have sex with men (MSM) in Sydney, New South Wales. E. histolytica is an invasive pathogenic amoeba that can cause invasive intestinal and extraintestinal amoebiasis. Entamoeba dispar is morphologically identical but is considered non-pathogenic and non-invasive.1 The three patients presented with a 1â3-week history of diarrhoea and abdominal pain. Routine bacterial cultures were negative for pathogens. Ova, cyst and parasite investigations showed cysts and trophozoites of E. histolytica/dispar complex in permanently stained, fixed faecal smears. Stool samples were tested for E. histolytica and E. dispar by polymerase chain reaction (PCR), using a previously described method.2 All three patients were positive for E. histolytica by PCR; sequencing of the amplicons verified the presence of E. histolytica DNA.
Ellis, JT & Morrison, DJ 2005, 'Application of bioinformatics to parasitology', International Journal For Parasitology, vol. 35, no. 5, pp. 463-464.
Hall, CA, Reichel, MP & Ellis, JT 2005, 'Neospora abortions in dairy cattle: diagnosis, mode of transmission and control', Veterinary Parasitology, vol. 128, no. 3-4, pp. 231-241.View/Download from: Publisher's site
To determine the contribution of neospora caninumm to abortions on a dairy farm in NSW (Australia), determine the mode of transmission and develop and trial a control option for infection
Hudson, AL & Ellis, JT 2005, 'Culture of Neospora caninum in the presence of a mycoplasma removal agent results in the selection of a mutant population of tachyzoites', Parasitology, vol. 130, no. 6, pp. 607-610.
Mycoplasmas are common contaminants of eukaryotic cells grown in tissue culture. A commercially available Mycoplasma Removal Agent (
Lei, Y, Birch, D, Davey, MW & Ellis, JT 2005, 'Subcellular fractionation and molecular characterization of the pellicle and plasmalemma of Neospora caninum', Parasitology, vol. 131, pp. 467-475.View/Download from: Publisher's site
A characteristic structural feature of Toxoplasma gondii and Neospora caninum is the presence of a triple-membrane pellicle, on the zoite stages of their complex life-cycle. Here we report the results of electron microscopic studies which show that the p
Lei, Y, Davey, MW & Ellis, JT 2005, 'Attachment and invasion of Toxoplasma gondii and Neospora caninum to epithelial and fibroblast cell lines in vitro', Parasitology, vol. 131, no. 5, pp. 583-590.
Attachment and invasion of Toxoplastna gondii and Neospora caninum to a cat and a dog fibroblast cell line and 2 epithelial cell lines (a cat kidney and Vero) were compared in vitro using fluorescence antibody methodology. In addition, trypsin treatment
Lei, Y, Davey, MW & Ellis, JT 2005, 'Auto fluorescence of Toxoplasma gondii and Neospora caninum cysts in vitro', Journal Of Parasitology, vol. 91, no. 1, pp. 17-23.View/Download from: Publisher's site
Autofluorescence of Toxoplasma gondii and Neospora caninum was Studied by fluorescence microscopy during their differentiation from tachyzoites to bradyzoites in vitro using Vero as host cells. Stage conversion into bradyzoites and cysts was confirmed by
Miller, CM, Quinn, HE, Ryce, C, Reichel, MP & Ellis, JT 2005, 'Reduction in transplacental transmission of Neospora caninum in outbred mice by vaccination', International Journal For Parasitology, vol. 35, no. 7, pp. 821-828.View/Download from: Publisher's site
Infection with the protozoan parasite Neospora caninum is an important cause of abortion in cattle. A major source of infection is transplacental transfer of the parasite from mother to offspring during pregnancy. This study describes investigations on t
Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2005, 'Detection of Dientamoeba fragilis in fresh stool specimens using PCR', International Journal For Parasitology, vol. 35, no. 1, pp. 57-62.View/Download from: Publisher's site
Dientamoeba fragilis is a trichomonad parasite that causes human gastrointestinal disease. Currently microscopy is considered to be the gold standard for diagnosis of D. fragilis infection. However, this method is time-consuming and relatively insensitiv
Stark, DJ, Beebe, NW, Marriott, DJ, Ellis, JT & Harkness, JL 2005, 'Prospective study of the prevalence, genotyping, and clinical relevance of Dientamoeba fragilis infections in an Australian population', Journal Of Clinical Microbiology, vol. 43, no. 6, pp. 2718-2723.View/Download from: Publisher's site
A prospective study was conducted over a 30-month period, in which fecal specimens from 6,750 patients were submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, Australia. Trophozoites of Dientamoeba fragilis were detected in 60
Quinn, HE, Miller, CM & Ellis, JT 2004, 'The cell-mediated immune response to Neospora caninum during pregnancy in the mouse is associated with a bias towards production of interleukin-4', International Journal For Parasitology, vol. 34, pp. 723-732.View/Download from: Publisher's site
Quinn, HE, Windsor, PA, Kirkland, PD & Ellis, JT 2004, 'An outbreak of abortion in a dairy herd associated with Neospora caninum and bovine pestivirus infection', Australian Veterinary Journal, vol. 82, no. 1 & 2, pp. 99-101.View/Download from: Publisher's site
Vonlaufen, N, Guetg, N, Naguleswaran, A, Müller, N, Björkman, C, Schares, G, von Blumroeder, D, Ellis, JT & Hemphill, A 2004, 'In vitro induction of Neospora caninum bradyzoites in vero cells reveals differential antigen expression| localization| and host-cell recognition of tachyzoites and bradyzoites', Infection And Immunity, vol. 72, pp. 576-583.View/Download from: Publisher's site
Ellis, JT, Morrison, DJ & Reichel, MP 2003, 'Genomics and its impact on parasitology and the potential for development of new parasite control methods', DNA and Cell Biology, vol. 22, no. 6, pp. 395-403.View/Download from: Publisher's site
Mohammed, OB, Davies Russell, A, Hussein, HS, Daszak, P & Ellis, JT 2003, 'Hammondia Heydorni from the Arabian mountain gazelle and red fox in Saudi Arabia', Journal of Parasitology, vol. 89, no. 3, pp. 535-539.View/Download from: Publisher's site
Morrison, DJ & Ellis, JT 2003, 'The design and analysis of microarray experiments: applications in parasitology', DNA and Cell Biology, vol. 22, no. 6, pp. 357-394.View/Download from: Publisher's site
Siverajah, S, Ryce, C, Morrison, DJ & Ellis, JT 2003, 'Characterization of an alpha tubulin gene sequence from Neospora caninum and Hammondia heydorni, and their comparison to homologous genes from Apicomplexa', Parasitology, vol. 126, pp. 561-569.View/Download from: Publisher's site
Dubey, J, Barr, BC, Barta, JR, Bjerkas, I, Björkman, C, Blagburn, BL, Bowman, DD, Buxton, D, Ellis, JT, Gottstein, B, Hemphill, A, Hill, DE, Howe, DK, Jenkins, MC, Kobayashi, Y, Koudela, B, Marsh, AE, Mattsson, J, McAllister, MM, Modry, D, Omata, Y, Sibley, LD, Speer, CA, Trees, SJ, Uggla, A, Upton, SJ, Williams, DJ & Lindsay, DS 2002, 'Redescription of Neospora caninum and its deifferntiation from related coccidia', International Journal for Parasitology, vol. 32, no. N/A, pp. 929-946.View/Download from: Publisher's site
Dubey, JP, Barr, BC, Barta, JR, Bjerkås, I, Björkman, C, Blagburn, BL, Bowman, DD, Buxton, D, Ellis, JT, Gottstein, B, Hemphill, A, Hill, DE, Howe, DK, Jenkins, MC, Kobayashi, Y, Koudela, B, Marsh, AE, Mattsson, JG, McAllister, MM, Modrý, D, Omata, Y, Sibley, LD, Speer, CA, Trees, AJ, Uggla, A, Upton, SJ, Williams, DJL & Lindsay, DS 2002, 'Redescription of Neospora caninum and its differentiation from related coccidia.', International journal for parasitology, vol. 32, no. 8, pp. 929-946.View/Download from: Publisher's site
Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.
Ellis, JT & Reichel, MP 2002, 'Control options for Neospora caninum infections in cattle - current state of knowledge', New Zealand Veterinary Journal, vol. 50, no. 3, pp. 86-92.View/Download from: Publisher's site
Noyes, H, Pratlong, F, Chance, M, Ellis, J, Lanotte, G & Dedet, JP 2002, 'A previously unclassified trypanosomatid responsible for human cutaneous lesions in Martinique (French West Indies) is the most divergent member of the genus Leishmania ss.', Parasitology, vol. 124, no. Pt 1, pp. 17-24.View/Download from: Publisher's site
Two cases of skin lesions similar to those caused by Leishmania parasites have been reported from Martinique. Parasites isolated from these lesions were unlike Leishmania reference strains by isoenzyme analysis and electron microscopy and were assumed to be monoxenous trypanosomatids which normally only infect invertebrates. Both strains have now been retyped by isoenzyme analysis and found to be identical to each other and distantly related to all other Leishmania species. The sequence of the 18S ribosomal RNA gene and partial sequences of the DNA polymerase alpha and RNA polymerase II largest subunit genes were obtained. These sequences indicated that the Martinique parasites clustered with L. enriettii and were basal to all other euleishmania. However, support for both the position basal to all euleishmania and the clustering with L. enriettii was low. The Martinique parasites may cluster with L. (Leishmania) or L. (Viannia) or form a novel clade within the euleishmania either with or without L. enriettii.
Quinn, HE, Miller, CM, Ryce, C, Windsor, PA & Ellis, JT 2002, 'Characterisation of an outbred pregnant mouse model of neospora caninum infection', Journal of parasitology, vol. 88, no. 4, pp. 691-696.View/Download from: Publisher's site
Quinn, HE, Miller, CM, Windsor, PA & Ellis, JT 2002, 'Characterisation of the first Australian isolate of Neospora caninum from cattle', Australian Veterinary Journal, vol. 80, no. 10, pp. 620-625.View/Download from: Publisher's site
Atkinson, R, Ryce, C, Miller, CM, Balu, S, Harper, PA & Ellis, JT 2001, 'Isolation of Neospora caninum genes detected during a Chronic Murine Infection', International Journal of Parasitology, vol. 31, pp. 67-71.View/Download from: Publisher's site
In order to isolate genes coding for antigens of Neospora caninum which are recognised by the host immune system during a chronic murine infection, a cDNA library was immunoscreened with pooled sera from mice which survived three independent infections by N. caninum. Two new genes from N. caninum were isolated and expressed in Escherichia coli. The genes identified include one homologous to GRA1 of Toxoplasma gondii, plus another (NCP20) previously unknown in any taxon. Both genes encode small polypeptides which induced an IgG response in the mouse and were also recognised by IgG from a cow chronically infected with N. caninum. These results are consistent with the hypothesis that the polypeptides encoded by these genes are a target for the host immune system during chronic infections of N. caninum.
Beebe, NW, Maung, J, van den Hurk, A, Ellis, JT & Cooper, RD 2001, 'Ribosomal DNA Spacer Genotypes of the Anopheles Bancroftii Group (Diptera: Culicidae) from Australia and Papua New Guinea', Insect Molecular Biology, vol. 10, no. 5, pp. 407-414.View/Download from: Publisher's site
Mosquitoes of the Anopheles bancroftii group collected from Northern Australia and Papua New Guinea (PNG) were investigated for sequence variation within the ribosomal DNA ITS2. Wing fringe morphology originally used to identify members of this group was compared to genotypes identified by restriction fragment length polymorphism analysis (RFLP) and heteroduplex analysis (HDA) of the rDNA ITS2. Members of this group separated into four RFLP genotypes (A, B, C and D) with some genotypes displaying wing fringe polymorphisms. Heteroduplex analysis of the ITS2 within and between populations identified genotype A as containing two geographically separate ITS2 sequences: A1 from the Northern Territory of Australia and A2 from Queensland and the Western Province of PNG. Genotypes B and C and genotypes C and D were found sympatric and appeared to be evolving independently suggesting the possibility of cryptic species. Genotype C contained two ITS2 sequence types within the genome.
Atkinson, R, Cook, RW, Reddacliff, LA, Rothwell, J, Broady, KW, Harper, PA & Ellis, JT 2000, 'Seroprevalence of Neospora caninum Infection Following an Abortive Outbreak in a Dairy Cattle Herd', Australian Veterinary Journal, vol. 78, no. 4, pp. 262-266.View/Download from: Publisher's site
To investigate the seroprevalence of Neospora caninum infection in a commercial dairy cattle herd, 15 months after detection of an abortion outbreak. PROCEDURE: Sera from the whole herd (n = 266) were examined for N caninum antibodies by indirect fluorescent antibody test (IFAT) and immunoblot analysis. Herd records were reviewed to collate serological results with abortion history, proximity to calving, and pedigree data. RESULTS: The seroprevalence of N caninum infection was 24% (63/266) for IFAT titre > or = 160, 29% (78/266) for immunoblot positive (+ve), and 31% (82/266) for IFAT > or = 160 and/or immunoblot +ve; 94% (59/63) of animals with IFAT > or = 160 were immunoblot +ve. The association between seropositivity (IFAT > or = 160 and/or immunoblot +ve) and history of abortion was highly significant (P < 0.001); the seroprevalence was 86% (18/21) in aborting cows, compared with 30% (50/164) in non-aborting animals. The abortion rate for seropositive cows was 26% (18/68) compared with 3% (3/117) for seronegative animals. IFAT titres of infected cows were higher within 2 months of calving than at other times (P < 0.001). The association between seropositivity in dams and daughters was highly significant (P = 0.009). CONCLUSIONS: The abortions were associated with N caninum infection and there was evidence of reactivation of latent infection close to calving and congenital transmission of infection. Immunodominant antigens identified by immunoblots may prove useful for improved diagnostic tests.
Atkinson, R, Harper, PA, Reichel, MP & Ellis, JT 2000, 'Progress in the serodiagnosis of Neospora caninum infections of cattle.', Parasitology today (Personal ed.), vol. 16, no. 3, pp. 110-114.View/Download from: Publisher's site
Neospora caninum is an apicomplexan protozoan that has become the focus of significant research attention worldwide. This organism infects a range of host species, including dogs, from which it was originally reported in 1984, but it is most important as a major cause of bovine abortion. As a result of the global importance of N. caninum, researchers have developed a number of serological tests to investigate the epidemiology of infection and disease. In this article, Robert Atkinson, Peter Harper, Michael Reichel and John Ellis consider progress made in the serodiagnosis of N. caninum.
Beebe, NW, Bakote'e, B, Ellis, JT & Cooper, RD 2000, 'Differential Ecology of Anopheles punctulatus and Three members of the Anopheles farauti Complex of Mosquitoes on Guadalcanal, Solomon Islands, Identified by PCR-RFLP Analysis', Medical & Veterinary Entomology, vol. 14, no. 3, pp. 308-312.View/Download from: Publisher's site
From a series of larval collections made across northern Guadalcanal during the dry season, OctoberNovember 1997, four members of the Anopheles punctulatus group of mosquitoes (Diptera: Culicidae) were identified using PCR-RFLP analysis. Anopheline larvae were found in 54/57 (95%) of the sites sampled, comprising An. farauti Laveran sensu stricto (32 sites), An. farauti species no. 2 (39 sites), An. farauti no. 7 (36 sites) and An. punctulatus Dönitz (10 sites). Anopheles punctulatus occurred only on the coastal plain, where it was associated with the more transient sites. Anopheles farauti sensu lato was more widespread throughout the survey region, with similar proportions of all three sibling species in both transient and permanent sites. Two members of the An. farauti complex, An. farauti s.s. and species no. 2, were found in brackish water. All breeding sites of An. punctulatus were cohabited by An. farauti s.l., sometimes by all three sibling species. Anopheles farauti s.s. was the only species collected on human bait, with a much higher biting rate early in the evening (57 bites/human/hour at 18.3020.00 hours) than later (0.8 bites/human/hour at 21.0024.00 hours).
Beebe, NW, Cooper, RD, Foley, DH & Ellis, JT 2000, 'A Phylogenetic Study of the Anopheles punctulatus Group of Malaria Vectors Comparing rDNA Sequence Alignments Derived from the Mitochondrial and Nuclear Small Ribosomal Subunits', Molecular Phylogenetics and Evolution, vol. 17, no. 3, pp. 430-436.View/Download from: Publisher's site
Beebe, NW, Cooper, RD, Foley, DH & Ellis, JT 2000, 'Populations of the South-West Pacific Malaria Vector Anopheles farauti s.s. Revealed by Ribosomal DNA Transcribed Spacer Polymorphisms', Heredity, vol. 84, no. 2, pp. 244-253.View/Download from: Publisher's site
Beebe, NW, Cooper, RD, Foley, DH & Ellis, JT 2000, 'Subset Partitioning of the Ribosomal DNA Small Subunit and its Effects on the Phylogeny of the Anopheles punctulatus Group', Insect Molecular Biology, vol. 9, no. 5, pp. 515-520.View/Download from: Publisher's site
Clarke, HE, Atkinson, R, Harper, PAW & Ellis, JT 2000, 'An investigation of the vertical transmission of Neospora caninum in mice', Asian-Australasian Journal of Animal Sciences, vol. 13, no. SUPPL. A, pp. 252-252.
Croan, DG & Ellis, J 2000, 'The Leishmania major RNA polymerase II largest subunit lacks a carboxy-terminus heptad repeat structure and its encoding gene is linked with the calreticulin gene', PROTIST, vol. 151, no. 1, pp. 57-68.View/Download from: Publisher's site
Croan, DG & Ellis, JT 2000, 'The Leishmania Major RNA Polymerase II Largest Subunit Lacks a Carboxy-Terminus Heptad Repeat Structure and its Encoding Gene is Linked with the Calretuculin Gene', Protist, vol. 151, no. 0, pp. 57-68.
The gene encoding the RNA polymerase II largest subunit (RPOIILS) has been isolated and sequenced from the kinetoplastid protozoan, Leishmania (Leishmania) major. The RPOIILS gene was shown to be present as a single copy and is composed of an uninterrupted open reading frame of 4.99 kb, specifying a protein 1663 aa in length with a predicted molecular mass of approximately 185 kDa. The carboxy terminus domain (CTD) of the RPOIILS from L. (L.) major, typical of the more evolutionary primitive protozoa, lacked a heptad repeat structure which is present in higher eukaryotes and some other protozoan phyla. Comparison of the predicted aa composition of the CTD from a diverse range of eukaryotic species revealed the abundance of Ser and Pro residues as the only discernible evolutionary conservative feature. A putative ATG start codon for an additional expressed sequence was located 1.1 kb downstream of the L. (L.) major RPOIILS gene stop codon. Nucleic acid database searches revealed the identity of this gene as that encoding the calcium binding protein calreticulin (CLT). The close proximity of the RPOIILS and CLT genes in L. (L.) major raises the possibility that these genes are transcribed as part of the same polycistronic unit.
Ellis, JT, Holmdahl, OJM, Ryce, C, Njenga, JM, Harper, PAW & Morrison, DA 2000, 'Molecular phylogeny of Besnoitia and the genetic relationships among Besnoitia of cattle, wildebeest and goats', PROTIST, vol. 151, no. 4, pp. 329-336.View/Download from: Publisher's site
Ellis, JT, Ryce, C, Atkinson, R, Balu, S, Jones, PM & Harper, PA 2000, 'Isolation, characterisation and expression of a GRA2 Homologue from Neospora Caninum', Parasitology, vol. 120, no. 0, pp. 383-390.
A cDNA library derived frommRNAof tachyzoites of Neospora caninum (NC-Liverpool strain) was screened with antisera from a cow naturally infected with N. caninum. The DNA sequence of 1 recombinant isolated predicted a signi®cant protein sequence homology of the gene product to the 28 kDa (GRA2) antigen of Toxoplasma gondii. Studies on the N. caninum gene coding for this antigen demonstrated the presence of a single intron ¯anked by 2 exons; the gene was also highly expressed in culture-derived tachyzoites. The antigen was expressed in Escherichia coli ; when injected into mice it stimulated the production of antibodies which detected a 29 kDa antigen ofN. caninum. Secondary structure predictions made for the N. caninum protein showed support for several amphipathic helices separated by loops and turns. The available evidence indicates maintenance of protein secondary structure, and not DNA or amino acid sequence, has occurred during the evolution of GRA2 proteins in N. caninum and T. gondii.
Noyes, H, Morrison, DJ, Chance, M & Ellis, JT 2000, 'Evidence for a Neotropical Origin of Leishmania', Memorias do Instituto Oswaldo Cruz, vol. 95, no. 4, pp. 575-578.
Atkinson, R, Harper, PA, Ryce, C, Morrison, DJ & Ellis, JT 1999, 'Comparison Of The Biological Characteristics Of Two Isolates Of Neospora Caninum', Parasitology, vol. 118, pp. 363-370.View/Download from: Publisher's site
This study compared the biological and genetic properties of a bovine (NC-SweB1) and a canine (NC-Liverpool) isolate of Neospora caninum. A mouse model for CNS infection demonstrated marked differences in pathogenicity between the isolates. NC-Liverpool
Beebe, NW, Ellis, JT, Cooper, RD & Saul, A 1999, 'DNA Sequence Analysis Of The Ribosomal Dna Its2 Region For The Anopheles Punctulatus Group Of Mosquitoes', Insect Molecular Biology, vol. 8, no. 3, pp. 381-390.View/Download from: Publisher's site
The internal transcribed spacer 2 (ITS2) from the ribosomal DNA was sequenced and characterized for ten cryptic species in the Anopheles punctulatus group, the members of which are major vectors of malaria and filariasis in the south-west Pacific. The le
Davison, H, Guy, F, Trees, SJ, Ryce, C, Ellis, JT, Otter, A, Jeffrey, M, Simpson, V & Holt, J 1999, 'In Vitro Isolation Of Neospora Caninum From A Stillborn Calf In The Uk', Research In Veterinary Science, vol. 67, no. 1, pp. 103-105.View/Download from: Publisher's site
Neospora caninum was isolated in Vero cell culture from the brain of a stillborn calf. This isolate (designated NC-LiVB1) is the first to be obtained from cattle in the United Kingdom and was confirmed as N. caninum by immunofluorescence with specific an
Ellis, JT, Mcmillan, D, Ryce, C, Payne, S, Atkinson, R & Harper, PA 1999, 'Development Of A Single Tube Nested Polymerase Chain Reaction Assay For The Detection Of Neospora Caninum DNA', International Journal For Parasitology, vol. 29, no. 10, pp. 1589-1596.View/Download from: Publisher's site
Sensitive detection techniques are required to study the life cycle of Neospora caninum and to diagnose infections, In this study, we describe the development of a PCR assay for N. caninum based on two successive amplification steps within a single tube.
Ellis, JT, Morrison, DJ, Liddell, S, Jenkins, MC, Mohammed, OB, Ryce, C & Dubey, J 1999, 'The Genus Hammondia Is Paraphyletic', Parasitology, vol. 118, pp. 357-362.View/Download from: Publisher's site
The phylogenetic relationships amongst Hammondia, Neospora and Toxoplasma were investigated by DNA sequence comparisons of the D2perD3 domain of the large subunit ribosomal DNA and the internal transcribed spacer 1. The results obtained allow us to rejec
Holmdahl, OJ, Morrison, DJ, Ellis, JT & Huong, L 1999, 'Evolution Of Ruminant Sarcocystis (sporozoa) Parasites Based On Small Subunit RDNA Sequences', Molecular Phylogenetics And Evolution, vol. 11, no. 1, pp. 27-37.View/Download from: Publisher's site
We present an evolutionary analysis of 13 species of Sarcocystis, including 4 newly sequenced species with ruminants as their intermediate host, based on complete small subunit rDNA sequences. Those species with ruminants as their intermediate host form
Jenkins, MC, Ellis, JT, Liddell, S, Ryce, C, Munday, B, Morrison, DJ & Dubey, J 1999, 'The Relationship Of Hammondia Hammondi And Sarcocystis Mucosa To Other Heteroxenous Cyst-farming Coccidia As Inferred By Phylogenetic Analysis Of The 18s Ssu Ribosomal DNA Sequence', Parasitology, vol. 119, pp. 135-142.View/Download from: Publisher's site
The complete sequence of the 18S small subunit (SSU) ribosomal DNA of Hammondia hammondi and Sarcocystis mucosa was obtained and compared to SSU rDNA sequences of Neospora caninum, Toxoplasma gondii, Besnoitia besnoiti, 2 species of Frenkelia, 3 species
Ellis, JT 1998, 'Polymerase Chain Reaction Approaches For The Detection Of Neospora Caninum And Toxoplasma Gondii', International Journal For Parasitology, vol. 28, no. 7, pp. 1053-1060.View/Download from: Publisher's site
This review summarises existing knowledge on the development and use of the polymerase chain reaction for the detection of DNA from Neospora and Toxoplasma. Several strategies which utilise the polymerase chain reaction for the diagnosis of toxoplasmosis
Ellis, JT, Amoyal, G, Ryce, C, Harper, PA, Clough, K, Homan, W & Brindley, PJ 1998, 'Comparison Of The Large Subunit Ribosomal DNA Of Neospora And Toxoplasma And Development Of A New Genetic Marker For Their Differentiation Based On The D2 Domain', Molecular And Cellular Probes, vol. 12, no. 1, pp. 1-13.View/Download from: Publisher's site
The latest release of the large subunit ribosomal database contains 429 sequences, yet only 10 (six nuclear and four mitochondrial) are derived from parasites of the phylum Apicomplexa. Three of these (all Toxoplasma gondii) were previously contained in
Noyes, H, Chance, M, Croan, DG & Ellis, JT 1998, 'Leishmania (Sauroleishmania) A Comment On Classification', Parasitology Today, vol. 14, no. 4, pp. 167-167.
Oakey, H, Ellis, JT & Gibson, L 1998, 'The Development Of Random Dna Probes Specific For Aeromonas Salmonicida', Journal Of Applied Microbiology, vol. 84, no. 1, pp. 37-46.
RAPD-PCR has been used to produce DNA probes for Aeromonas salmonicida. DNA hybridization studies showed that RAPD-PCR fragments of the same size did not necessarily hybridize to each other and therefore these sequences were not always homologous. Howeve
Barber, JS, Gasser, RB, Ellis, J, Reichel, MP, McMillan, D & Trees, AJ 1997, 'Prevalence of antibodies to Neospora caninum in different canid populations', JOURNAL OF PARASITOLOGY, vol. 83, no. 6, pp. 1056-1058.View/Download from: Publisher's site
Barr, BC, Bjerkas, I, Buxton, D, Conrad, PA, Dubey, JP, Ellis, JT, Jenkins, MC, Johnston, SA, Lindsay, DS, Sibley, D, Trees, AJ & Wouda, W 1997, 'Neosporosis - Report of the International Neospora Workshop', COMPENDIUM ON CONTINUING EDUCATION FOR THE PRACTICING VETERINARIAN, vol. 19, no. 4, pp. S120-&.
Croan, DG, Morrison, DJ & Ellis, JT 1997, 'Evolution Of The Genus Leishmania Revealed By Comparison Of DNA And Rna Polymerase Gene Sequences', Molecular And Biochemical Parasitology, vol. 89, no. 2, pp. 149-159.View/Download from: Publisher's site
Previous hypotheses of Leishmania evolution are undermined by limitations in the phylogenetic reconstruction method employed or due to the omission of key parasites. In this. experiment, sequences of the gene encoding the DNA polpmerase alpha catalytic p
Morrison, DJ & Ellis, JT 1997, 'Effects Of Nucleotide Sequence Alignment On Phylogeny Estimation A Case Study Of 18s RDNAs Of Apicomplexa', Molecular Biology And Evolution, vol. 14, no. 4, pp. 428-441.View/Download from: Publisher's site
The reconstruction of phylogenetic history is predicated on being able to accurately establish hypotheses of character homology, which involves sequence alignment for studies based on molecular sequence data. In an empirical study investigating nucleotid
Croan, D & Ellis, J 1996, 'Phylogenetic relationships between Leishmania, Viannia and Sauroleishmania inferred from comparison of a variable domain within the RNA polymerase II largest subunit gene', MOLECULAR AND BIOCHEMICAL PARASITOLOGY, vol. 79, no. 1, pp. 97-102.View/Download from: Publisher's site
Mertens, C, Tenter, AM, Vietmeyer, C, Ellis, JT & Johnson, AM 1996, 'Production Of A Recombinant Fusion Protein Of Sarcocystis Tenella And Evaluation Of Its Diagnostic Potential In An Elisa', Veterinary Parasitology, vol. 65, no. 3-4, pp. 185-197.View/Download from: Publisher's site
We have isolated a cDNA clone encoding an antigenic polypeptide of Sarcocystis tenella by screening a cystozoite-derived cDNA library in lambda gt11 with antibodies from sheep infected experimentally with S. tenella. This clone, termed STC29, was subclon
Oakey, H, Ellis, JT & Gibson, L 1996, 'A Biochemical Protocol For The Differentiation Of Current Genomospecies Of Aeromonas', Zentralblatt Fur Bakteriologie-International Journal..., vol. 284, no. 1, pp. 32-46.
A data file consisting of 40 biochemical and physiological tests for the differentiation of aeromonads was constructed based upon existing published data from various geographical locations and laboratories. The data file covers all the current genomospe
Oakey, H, Ellis, JT & Gibson, L 1996, 'Differentiation Of Aeromonas Genomospecies Using Random Amplified Polymorphic DNA Polymerase Chain Reaction (RAPD-PCR)', Journal Of Applied Microbiology, vol. 80, no. 4, pp. 402-410.
Random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) was used to investigate the differentiation of the genus Aeromonas at the genomospecies level. Of 20 primers evaluated, six produced profiles which contained multiple bands capable of
Payne, S & Ellis, J 1996, 'Detection of Neospora caninum DNA by the polymerase chain reaction', INTERNATIONAL JOURNAL FOR PARASITOLOGY, vol. 26, no. 4, pp. 347-351.View/Download from: Publisher's site
ELLIS, J & MORRISON, D 1995, 'EFFECTS OF SEQUENCE ALIGNMENT ON THE PHYLOGENY OF SARCOCYSTIS DEDUCED FROM 18S RDNA SEQUENCES', PARASITOLOGY RESEARCH, vol. 81, no. 8, pp. 696-699.View/Download from: Publisher's site
ELLIS, J, MORRISON, DA & KALINNA, B 1995, 'COMPARISON OF THE PATTERNS OF CODON USAGE AND BIAS BETWEEN BRUGIA, ECHINOCOCCUS, ONCHOCERCA AND SCHISTOSOMA SPECIES', PARASITOLOGY RESEARCH, vol. 81, no. 5, pp. 388-393.View/Download from: Publisher's site
Codon usage and bias has been examined in 20 genes of Schistosoma mansoni. Significant heterogeneity was detected in the patterns of codon usage and bias among genes by metric multidimensional scaling and three general indictors of bias (GC(3s,) N-c and
Ellis, JT, Luton, K, Whitworth, G & Johnson, AM 1995, 'Phylogenetic relationships between Toxoplasma and sarcocystis deduced from a comparison of 18S rDNA sequences', Parasitology, vol. 110, no. 5, pp. 521-528.View/Download from: Publisher's site
The current taxonomy of parasites in the genus Sarcocystis is largely based on morphological characteristics as well as on host specificity and life-cycle structure. Recently, phylogenetic analyses of partial ribosomal RNA (rRNA) sequences provided support for paraphyly of Sarcocystis. We have tested the validity of this hypothesis by sequencing the complete 18S rRNA genes of Sarcocystis arieticanis, Sarcocystis gigantea and Sarcocystis tenella and comparing them with gene sequences derived from other taxa of the phylum Apicomplexa. The results obtained from this study do not reject the hypothesis of monophyly of Sarcocystis species, although the bootstrap data were inconclusive for some species. © 1995, Cambridge University Press. All rights reserved.
Oakey, H, Ellis, JT & Gibson, L 1995, 'Can Rapd-Pcr Be Used To Discriminate Between The Hybridization Groups Of Aeromonas', Medical Microbiology Letters, vol. 4, no. 7, pp. 373-381.
We report the preliminary results obtained from an investigation into the suitability of the random amplified polymorphic DNA polymerase chain reaction to discriminate between the currently recognised DNA hybridisation groups of the genus Aeromonas. The
ELLIS, J, LUTON, K, BAVERSTOCK, PR, BRINDLEY, PJ, NIMMO, KA & JOHNSON, AM 1994, 'THE PHYLOGENY OF NEOSPORA-CANINUM', MOLECULAR AND BIOCHEMICAL PARASITOLOGY, vol. 64, no. 2, pp. 303-311.View/Download from: Publisher's site
Ellis, JT, Morrison, DJ, Avery, D & Johnson, AM 1994, 'Codon Usage And Bias Among Individual Genes Of The Coccidia And Piroplasms', Parasitology, vol. 109, pp. 265-272.View/Download from: Publisher's site
Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the tw
Russell, RC, Doggett, SL, Munro, R, Ellis, J, Avery, D, Hunt, C & Dickeson, D 1994, 'Lyme disease: a search for a causative agent in ticks in south-eastern Australia.', Epidemiology and infection, vol. 112, no. 2, pp. 375-384.View/Download from: Publisher's site
Attempts were made to identify the causative organism of Lyme disease in Australia from possible tick vectors. Ticks were collected in coastal areas of New South Wales, Australia, from localities associated with putative human infections. The ticks were dissected; a portion of the gut contents was examined for spirochaetes by microscopy, the remaining portion inoculated into culture media. The detection of spirochaetes in culture was performed using microscopy, and immunochemical and molecular (PCR) techniques. Additionally, whole ticks were tested with PCR for spirochaetes. From 1990 to 1992, approximately 12,000 ticks were processed for spirochaetes. No evidence of Borrelia burgdorferi or any other spirochaete was recovered from or detected in likely tick vectors. Some spirochaete-like objects detected in the cultures were shown to be artifacts, probably aggregates of bacterial flagellae. There is no definitive evidence for the existence in Australia of B. burgdorferi the causative agent of true Lyme disease, or for any other tick-borne spirochaete that may be responsible for a local syndrome being reported as Lyme disease.
ELLIS, J, GRIFFIN, H, MORRISON, D & JOHNSON, AM 1993, 'ANALYSIS OF DINUCLEOTIDE FREQUENCY AND CODON USAGE IN THE PHYLUM APICOMPLEXA', GENE, vol. 126, no. 2, pp. 163-170.View/Download from: Publisher's site
Johnson, AM, Makioka, A & Ellis, JT 1993, 'A strategy for cloning a DNA polymerase gene of Toxoplasma gondii.', NATO ASI series. Series H, Cell biology, vol. 78, pp. 43-50.
Makioka, A, Stavros, B, Ellis, JT & Johnson, AM 1993, 'Detection and characterization of DNA polymerase activity in Toxoplasma gondii', Parasitology, vol. 107, no. 2, pp. 135-139.View/Download from: Publisher's site
A DNA polymerase activity has been detected and characterized in crude extracts from tachyzoites of Toxoplasma gondii. The enzyme has a sedimentation coefficient of 6.4 S, corresponding to an approximate molecular weight of 150000 assuming a globular shape. Like mammalian DNA polymerase a, the DNA polymerase of T. gondii was sensitive to N-ethylmaleimide and inhibited by high ionic strength. However, the enzyme activity was not inhibited by aphidicolin which is an inhibitor of mammalian DNA polymerases α, δ and ∊ and also cytosine-β-D-arabinofuranoside-5'-triphosphate which is an inhibitor of a polymerase. The activity was inhibited by 2,3-dideoxythymidine-5'-triphosphate which is an inhibitor of mammalian DNA polymerase β and γ. Magnesium ions (Mg2+) were absolutely required for activity and its optimal concentration was 6 mM, The optimum potassium (K+) concentration was 50 mM and a higher concentration of K+ markedly inhibited the activity. Activity was optimal at pH 8. Monoclonal antibodies against human DNA polymerase a did not bind to DNA polymerase of T. gondii. Thus the T. gondii enzyme differs from the human enzymes and may be a useful target for the design of toxoplasmacidal drugs. © 1993, Cambridge University Press. All rights reserved.
Rohde, K, Hefford, C, Ellis, JT, Hanlon, PL, Johnson, AM, Watson, NF & Dittmann, S 1993, 'Contributions To The Phylogeny Of Platyhelminthes Based On Partial Sequencing Of 18s Ribosomal DNA', International Journal For Parasitology, vol. 23, no. 6, pp. 705-724.View/Download from: Publisher's site
Partial sequencing of the 18S ribosomal DNA gene of one nemertean and 13 free-living and parasitic Platyhelminthes (556 nucleotides), and of one nemertean and 20 Platyhelminthes (556 nucleotides) was used to test several hypotheses concerning the phyloge
ELLIS, J, HEFFORD, C, BAVERSTOCK, PR, DALRYMPLE, BP & JOHNSON, AM 1992, 'RIBOSOMAL DNA-SEQUENCE COMPARISON OF BABESIA AND THEILERIA', MOLECULAR AND BIOCHEMICAL PARASITOLOGY, vol. 54, no. 1, pp. 87-95.View/Download from: Publisher's site
Messenger RNA has been extracted from oocysts of Eimeria maxima. Using the techniques of in vitro translation and SDS-polyacrylamide gel electrophoresis, we have been able to show that major changes in gene transcription occur during sporulation. Following an overall reduction in the abundance of many mRNAs, several genes identified as the result of an increase in the abundance of their transcripts, are highly expressed during the latter stages of sporulation. A study of two genes whose transcription is down-regulated has provided evidence which shows that both single copy and repetitive sequences are regulated during sporulation of the oocyst. © 1991, Cambridge University Press. All rights reserved.
ELLIS, JT & CRAMPTON, JM 1991, 'DIFFERENCES BETWEEN LEISHMANIA-(LEISHMANIA)-CHAGASI, L-(L)-INFANTUM AND L-(L)-DONOVANI AS SHOWN BY DNA FINGERPRINTING', MEMORIAS DO INSTITUTO OSWALDO CRUZ, vol. 86, no. 4, pp. 479-481.View/Download from: Publisher's site
JOHNSON, AM, FIELKE, R, ELLIS, J, ODONOGHUE, PJ & BAVERSTOCK, PR 1991, 'THE PHYLOGENETIC-RELATIONSHIPS OF THE GENUS EIMERIA BASED ON COMPARISON OF PARTIAL SEQUENCES OF 18S RIBOSOMAL-RNA', SYSTEMATIC PARASITOLOGY, vol. 18, no. 1, pp. 1-8.View/Download from: Publisher's site
RRNA and a heterologous cloned rDNA probe have been used to detect the rRNA genes of Eimeria species which infect the chicken, and has allowed the isolation and preliminary characterization of cloned rDNA sequences from a genomic DNA library of Eimeriatenella. It is demonstrated that rRNA and rDNA probes can be used to identify individual Eimeria species by the restriction fragment patterns detected after Southern hybridization. In addition, studies have shown that the large and small subunit rRNAs are expressed throughout sporulation. © 1990, Cambridge University Press. All rights reserved.
There is increasing support for the presence of viruses and virus-like particles inside protozoan cells. This study describes viral-like RNA molecules that have been detected in two species of Eimeria that infect the chicken. The RNA molecule identified in E. maxima has been characterized: subcellular fractionation studies have shown that the RNA is present in the cytoplasm, probably as an abundant ribonucleoprotein that is insensitive to RNAse A treatment. Electron microscopy has demonstrated that this RNA molecule is double stranded. In addition, all E. maxima strains examined so far contain this RNA molecule. © 1990, Cambridge University Press. All rights reserved.
ELLIS, J, KNAPP, T & CRAMPTON, J 1989, 'CLONING OF A POLYMORPHIC DNA FRAGMENT FROM THE GENOME OF LEISHMANIA-DONOVANI', MOLECULAR AND BIOCHEMICAL PARASITOLOGY, vol. 34, no. 3, pp. 261-268.View/Download from: Publisher's site
Meng, Q, Wu, J, Ellis, J & Kennedy, PJ 2017, 'Dynamic island model based on spectral clustering in genetic algorithm', Proceedings of the International Joint Conference on Neural Networks, International Joint Conference on Neural Networks, IEEE, Anchorage, AK, USA, pp. 1724-1731.View/Download from: Publisher's site
© 2017 IEEE. How to maintain relative high diversity is important to avoid premature convergence in population-based optimization methods. Island model is widely considered as a major approach to achieve this because of its flexibility and high efficiency. The model maintains a group of sub-populations on different islands and allows sub-populations to interact with each other via predefined migration policies. However, current island model has some drawbacks. One is that after a certain number of generations, different islands may retain quite similar, converged sub-populations thereby losing diversity and decreasing efficiency. Another drawback is that determining the number of islands to maintain is also very challenging. Meanwhile initializing many sub-populations increases the randomness of island model. To address these issues, we proposed a dynamic island model (DIM-SP) which can force each island to maintain different sub-populations, control the number of islands dynamically and starts with one sub-population. The proposed island model outperforms the other three state-of-the-art island models in three baseline optimization problems including job shop scheduler, travelling salesmen, and quadratic multiple knapsack.
Barratt, J, Stark, D, Roberts, T, Marriott, D, Harkness, J & Ellis, J 2010, 'Evaluation of diagnostic techniques for the detection of Dientamoeba fragilis in clinical stool specimens', 12th International Congress of Parasitology, Melbourne, Australia.
Ellis, J, Barratt, J, Harkness, J, Marriott, D & Stark, D 2010, 'Dientamoeba fragilis: Evidence for its role as a cause of human gastrointestinal disease', 12th International Congress of Parasitology, Melbourne, Australia.
Barratt, JOEL, Stark, D, Van Hal, S, Ellis, JOHN, Marriott, D & Harkness, J 2008, 'Limited genetic diversity among genotypes of Entercytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia', ASP & ARC/NHMRC Research Network for Parasitology Annual Conference, Adelaide, Australia.
Roberts, T, Barratt, J, Stark, D, van hal, S, Ellis, J, Marriott, D & Harkness, J 2008, 'Limited genetic diversity among genotypes of Entercytozoon bieneusi strains isolated from HIV-infected patients from Sydney, Australia', The Australian Society for Microbiology scientific meeting & exhibition, Sydney, Australia.
Barry, A, Hansen, D & Ellis, J 2016, 'Naturally acquired immunity to malaria', Cambridge University Press.
Fenton, A & Ellis, J 2016, 'Mathematical modelling of infectious diseases', Cambridge University Press.
Dr Damien Stark, St. Vincent's Hospital Sydney
Dr Rogan Lee, ICPMR Westmead Hospital
Dr Stephanie Laferty-Fletcher, Public Health Unit, Liverpool
<span id='badgeCont594986' style='width:126px'><script src='http://labs.researcherid.com/mashlets?el=badgeCont594986&mashlet=badge&…;