Veterinary Biosciences - Research Publications

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    Bulinus truncatus transcriptome - a resource to enable molecular studies of snail and schistosome biology.
    Stroehlein, AJ ; Korhonen, PK ; Rollinson, D ; Stothard, JR ; Hall, RS ; Gasser, RB ; Young, ND (Elsevier BV, 2021)
    Despite advances in high-throughput sequencing and bioinformatics, molecular investigations of snail intermediate hosts that transmit parasitic trematodes are scant. Here, we report the first transcriptome for Bulinus truncatus - a key intermediate host of Schistosoma haematobium - a blood fluke that causes urogenital schistosomiasis in humans. We assembled this transcriptome from short- and long-read RNA-sequence data. From this transcriptome, we predicted 12,998 proteins, 58% of which had orthologs in Biomphalaria glabrata - an intermediate host of Schistosoma mansoni - a blood fluke that causes hepato-intestinal schistosomiasis. We predicted that select protein groups are involved in signal transduction, cell growth and death, the immune system, environmental adaptation and/or the excretory/secretory system, suggesting roles in immune responses, pathogen defence and/or parasite-host interactions. The transcriptome of Bu. truncatus provides a useful resource to underpin future molecular investigations of this and related snail species, and its interactions with pathogens including S. haematobium. The present resource should enable comparative investigations of other molluscan hosts of socioeconomically important parasites in the future.
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    The genome and developmental transcriptome of the strongylid nematode Haemonchus contortus
    Schwarz, EM ; Korhonen, PK ; Campbell, BE ; Young, ND ; Jex, AR ; Jabbar, A ; Hall, RS ; Mondal, A ; Howe, AC ; Pell, J ; Hofmann, A ; Boag, PR ; Zhu, X-Q ; Gregory, TR ; Loukas, A ; Williams, BA ; Antoshechkin, I ; Brown, CT ; Sternberg, PW ; Gasser, RB (BMC, 2013-01-01)
    BACKGROUND: The barber's pole worm, Haemonchus contortus, is one of the most economically important parasites of small ruminants worldwide. Although this parasite can be controlled using anthelmintic drugs, resistance against most drugs in common use has become a widespread problem. We provide a draft of the genome and the transcriptomes of all key developmental stages of H. contortus to support biological and biotechnological research areas of this and related parasites. RESULTS: The draft genome of H. contortus is 320 Mb in size and encodes 23,610 protein-coding genes. On a fundamental level, we elucidate transcriptional alterations taking place throughout the life cycle, characterize the parasite's gene silencing machinery, and explore molecules involved in development, reproduction, host-parasite interactions, immunity, and disease. The secretome of H. contortus is particularly rich in peptidases linked to blood-feeding activity and interactions with host tissues, and a diverse array of molecules is involved in complex immune responses. On an applied level, we predict drug targets and identify vaccine molecules. CONCLUSIONS: The draft genome and developmental transcriptome of H. contortus provide a major resource to the scientific community for a wide range of genomic, genetic, proteomic, metabolomic, evolutionary, biological, ecological, and epidemiological investigations, and a solid foundation for biotechnological outcomes, including new anthelmintics, vaccines and diagnostic tests. This first draft genome of any strongylid nematode paves the way for a rapid acceleration in our understanding of a wide range of socioeconomically important parasites of one of the largest nematode orders.
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    The Opisthorchis viverrini genome provides insights into life in the bile duct
    Young, ND ; Nagarajan, N ; Lin, SJ ; Korhonen, PK ; Jex, AR ; Hall, RS ; Safavi-Hemami, H ; Kaewkong, W ; Bertrand, D ; Gao, S ; Seet, Q ; Wongkham, S ; Teh, BT ; Wongkham, C ; Intapan, PM ; Maleewong, W ; Yang, X ; Hu, M ; Wang, Z ; Hofmann, A ; Sternberg, PW ; Tan, P ; Wang, J ; Gasser, RB (NATURE PUBLISHING GROUP, 2014-07-01)
    Opisthorchiasis is a neglected, tropical disease caused by the carcinogenic Asian liver fluke, Opisthorchis viverrini. This hepatobiliary disease is linked to malignant cancer (cholangiocarcinoma, CCA) and affects millions of people in Asia. No vaccine is available, and only one drug (praziquantel) is used against the parasite. Little is known about O. viverrini biology and the diseases that it causes. Here we characterize the draft genome (634.5 Mb) and transcriptomes of O. viverrini, elucidate how this fluke survives in the hostile environment within the bile duct and show that metabolic pathways in the parasite are highly adapted to a lipid-rich diet from bile and/or cholangiocytes. We also provide additional evidence that O. viverrini and other flukes secrete proteins that directly modulate host cell proliferation. Our molecular resources now underpin profound explorations of opisthorchiasis/CCA and the design of new interventions.
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    Genetic blueprint of the zoonotic pathogen Toxocara canis
    Zhu, X-Q ; Korhonen, PK ; Cai, H ; Young, ND ; Nejsum, P ; von Samson-Himmelstjerna, G ; Boag, PR ; Tan, P ; Li, Q ; Min, J ; Yang, Y ; Wang, X ; Fang, X ; Hall, RS ; Hofmann, A ; Sternberg, PW ; Jex, AR ; Gasser, RB (NATURE RESEARCH, 2015-02-01)
    Toxocara canis is a zoonotic parasite of major socioeconomic importance worldwide. In humans, this nematode causes disease (toxocariasis) mainly in the under-privileged communities in developed and developing countries. Although relatively well studied from clinical and epidemiological perspectives, to date, there has been no global investigation of the molecular biology of this parasite. Here we use next-generation sequencing to produce a draft genome and transcriptome of T. canis to support future biological and biotechnological investigations. This genome is 317 Mb in size, has a repeat content of 13.5% and encodes at least 18,596 protein-coding genes. We study transcription in a larval, as well as adult female and male stages, characterize the parasite's gene-silencing machinery, explore molecules involved in development or host-parasite interactions and predict intervention targets. The draft genome of T. canis should provide a useful resource for future molecular studies of this and other, related parasites.
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    Time-Dependent Transcriptional Changes in Axenic Giardia duodenalis Trophozoites
    Ansell, BRE ; McConville, MJ ; Baker, L ; Korhonen, PK ; Young, ND ; Hall, RS ; Rojas, CAA ; Svard, SG ; Gasser, RB ; Jex, AR ; Hehl, AB (PUBLIC LIBRARY SCIENCE, 2015-12-01)
    Giardia duodenalis is the most common gastrointestinal protozoan parasite of humans and a significant contributor to the global burden of both diarrheal disease and post-infectious chronic disorders. Although G. duodenalis can be cultured axenically, significant gaps exist in our understanding of the molecular biology and metabolism of this pathogen. The present study employed RNA sequencing to characterize the mRNA transcriptome of G. duodenalis trophozoites in axenic culture, at log (48 h of growth), stationary (60 h), and declining (96 h) growth phases. Using ~400-times coverage of the transcriptome, we identified 754 differentially transcribed genes (DTGs), mainly representing two large DTG groups: 438 that were down-regulated in the declining phase relative to log and stationary phases, and 281 that were up-regulated. Differential transcription of prominent antioxidant and glycolytic enzymes implicated oxygen tension as a key factor influencing the transcriptional program of axenic trophozoites. Systematic bioinformatic characterization of numerous DTGs encoding hypothetical proteins of unknown function was achieved using structural homology searching. This powerful approach greatly informed the differential transcription analysis and revealed putative novel antioxidant-coding genes, and the presence of a near-complete two-component-like signaling system that may link cytosolic redox or metabolite sensing to the observed transcriptional changes. Motif searching applied to promoter regions of the two large DTG groups identified different putative transcription factor-binding motifs that may underpin global transcriptional regulation. This study provides new insights into the drivers and potential mediators of transcriptional variation in axenic G. duodenalis and provides context for static transcriptional studies.
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    Identification of G protein-coupled receptors in Schistosoma haematobium and S. mansoni by comparative genomics
    Campos, TDL ; Young, ND ; Korhonen, PK ; Hall, RS ; Mangiola, S ; Lonie, A ; Gasser, RB (BMC, 2014-05-27)
    BACKGROUND: Schistosomiasis is a parasitic disease affecting ~200 million people worldwide. Schistosoma haematobium and S. mansoni are two relatively closely related schistosomes (blood flukes), and the causative agents of urogenital and hepatointestinal schistosomiasis, respectively. The availability of genomic, transcriptomic and proteomic data sets for these two schistosomes now provides unprecedented opportunities to explore their biology, host interactions and schistosomiasis at the molecular level. A particularly important group of molecules involved in a range of biological and developmental processes in schistosomes and other parasites are the G protein-coupled receptors (GPCRs). Although GPCRs have been studied in schistosomes, there has been no detailed comparison of these receptors between closely related species. Here, using a genomic-bioinformatic approach, we identified and characterised key GPCRs in S. haematobium and S. mansoni (two closely related species of schistosome). METHODS: Using a Hidden Markov Model (HMM) and Support Vector Machine (SVM)-based pipeline, we classified and sub-classified GPCRs of S. haematobium and S. mansoni, combined with phylogenetic and transcription analyses. RESULTS: We identified and classified classes A, B, C and F as well as an unclassified group of GPCRs encoded in the genomes of S. haematobium and S. mansoni. In addition, we characterised ligand-specific subclasses (i.e. amine, peptide, opsin and orphan) within class A (rhodopsin-like). CONCLUSIONS: Most GPCRs shared a high degree of similarity and conservation, except for members of a particular clade (designated SmGPR), which appear to have diverged between S. haematobium and S. mansoni and might explain, to some extent, some of the underlying biological differences between these two schistosomes. The present set of annotated GPCRs provides a basis for future functional genomic studies of cellular GPCR-mediated signal transduction and a resource for future drug discovery efforts in schistosomes.
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    Pipeline for the identification and classification of ion channels in parasitic flatworms
    Nor, B ; Young, ND ; Korhonen, PK ; Hall, RS ; Tan, P ; Lonie, A ; Gasser, RB (BMC, 2016-03-16)
    BACKGROUND: Ion channels are well characterised in model organisms, principally because of the availability of functional genomic tools and datasets for these species. This contrasts the situation, for example, for parasites of humans and animals, whose genomic and biological uniqueness means that many genes and their products cannot be annotated. As ion channels are recognised as important drug targets in mammals, the accurate identification and classification of parasite channels could provide major prospects for defining unique targets for designing novel and specific anti-parasite therapies. Here, we established a reliable bioinformatic pipeline for the identification and classification of ion channels encoded in the genome of the cancer-causing liver fluke Opisthorchis viverrini, and extended its application to related flatworms affecting humans. METHODS: We built an ion channel identification + classification pipeline (called MuSICC), employing an optimised support vector machine (SVM) model and using the Kyoto Encyclopaedia of Genes and Genomes (KEGG) classification system. Ion channel proteins were first identified and grouped according to amino acid sequence similarity to classified ion channels and the presence and number of ion channel-like conserved and transmembrane domains. Predicted ion channels were then classified to sub-family using a SVM model, trained using ion channel features. RESULTS: Following an evaluation of this pipeline (MuSICC), which demonstrated a classification sensitivity of 95.2 % and accuracy of 70.5 % for known ion channels, we applied it to effectively identify and classify ion channels in selected parasitic flatworms. CONCLUSIONS: MuSICC provides a practical and effective tool for the identification and classification of ion channels of parasitic flatworms, and should be applicable to a broad range of organisms that are evolutionarily distant from taxa whose ion channels are functionally characterised.
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    Molecular evidence for distinct modes of nutrient acquisition between visceral and neurotropic schistosomes of birds
    Leontovyc, R ; Young, ND ; Korhonen, PK ; Hall, RS ; Bulantova, J ; Jerabkova, V ; Kasny, M ; Gasser, RB ; Horak, P (NATURE PUBLISHING GROUP, 2019-02-04)
    Trichobilharzia species are parasitic flatworms (called schistosomes or flukes) that cause important diseases in birds and humans, but very little is known about their molecular biology. Here, using a transcriptomics-bioinformatics-based approach, we explored molecular aspects pertaining to the nutritional requirements of Trichobilharzia szidati ('visceral fluke') and T. regenti ('neurotropic fluke') in their avian host. We studied the larvae of each species before they enter (cercariae) and as they migrate (schistosomules) through distinct tissues in their avian (duck) host. Cercariae of both species were enriched for pathways or molecules associated predominantly with carbohydrate metabolism, oxidative phosphorylation and translation of proteins linked to ribosome biogenesis, exosome production and/or lipid biogenesis. Schistosomules of both species were enriched for pathways or molecules associated with processes including signal transduction, cell turnover and motility, DNA replication and repair, molecular transport and/or catabolism. Comparative informatic analyses identified molecular repertoires (within, e.g., peptidases and secretory proteins) in schistosomules that can broadly degrade macromolecules in both T. szidati and T. regenti, and others that are tailored to each species to selectively acquire nutrients from particular tissues through which it migrates. Thus, this study provides molecular evidence for distinct modes of nutrient acquisition between the visceral and neurotropic flukes of birds.
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    Common workflow language (CWL)-based software pipeline for de novo genome assembly from long- and short-read data
    Korhonen, PK ; Hall, RS ; Young, ND ; Gasser, RB (BioMed Central, 2019-04-01)
    Background Here, we created an automated pipeline for the de novoassembly of genomes from Pacific Biosciences long-read and Illumina short-read data using common workflow language (CWL). To evaluate the performance of this pipeline, we assembled the nuclear genomes of the eukaryotes Caenorhabditis elegans (∼100 Mb), Drosophila melanogaster (∼138 Mb), and Plasmodium falciparum (∼23 Mb) directly from publicly accessible nucleotide sequence datasets and assessed the quality of the assemblies against curated reference genomes. Findings We showed a dependency of the accuracy of assembly on sequencing technology and GC content and repeatedly achieved assemblies that meet the high standards set by the National Human Genome Research Institute, being applicable to gene prediction and subsequent genomic analyses. Conclusions This CWL pipeline overcomes current challenges of achieving repeatability and reproducibility of assembly results and offers a platform for the re-use of the workflow and the integration of diverse datasets. This workflow is publicly available via GitHub (https://github.com/vetscience/Assemblosis) and is currently applicable to the assembly of haploid and diploid genomes of eukaryotes.
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    Marked mitochondrial genetic variation in individuals and populations of the carcinogenic liver fluke Clonorchis sinensis
    Kinkar, L ; Korhonen, PK ; Wang, D ; Zhu, X-Q ; Chelomina, GN ; Wang, T ; Hall, RS ; Koehler, A ; Harliwong, I ; Yang, B ; Fink, JL ; Young, ND ; Gasser, RB ; Blair, D (PUBLIC LIBRARY SCIENCE, 2020-08-01)
    Clonorchiasis is a neglected tropical disease caused by the Chinese liver fluke, Clonorchis sinensis, and is often associated with a malignant form of bile duct cancer (cholangiocarcinoma). Although some aspects of the epidemiology of clonorchiasis are understood, little is known about the genetics of C. sinensis populations. Here, we conducted a comprehensive genetic exploration of C. sinensis from endemic geographic regions using complete mitochondrial protein gene sets. Genomic DNA samples from C. sinensis individuals (n = 183) collected from cats and dogs in China (provinces of Guangdong, Guangxi, Hunan, Heilongjiang and Jilin) as well as from rats infected with metacercariae from cyprinid fish from the Russian Far East (Primorsky Krai region) were deep sequenced using the BGISEQ-500 platform. Informatic analyses of mitochondrial protein gene data sets revealed marked genetic variation within C. sinensis; significant variation was identified within and among individual worms from distinct geographical locations. No clear affiliation with a particular location or host species was evident, suggesting a high rate of dispersal of the parasite across endemic regions. The present work provides a foundation for future biological, epidemiological and ecological studies using mitochondrial protein gene data sets, which could aid in elucidating associations between particular C. sinensis genotypes/haplotypes and the pathogenesis or severity of clonorchiasis and its complications (including cholangiocarcinoma) in humans.