Publications by authors named "Guangxu Ma"

30 Publications

  • Page 1 of 1

A Zinc Metalloprotease Is Required for Molting and Survival in Parasitic Nematode .

Front Cell Dev Biol 2021 13;9:695003. Epub 2021 Jul 13.

College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, China.

Molting is of great importance for the survival and development of nematodes. Nematode astacins (NAS), a large family of zinc metalloproteases, have been proposed as novel anthelmintic targets due to their multiple roles in biological processes of parasitic nematodes. In this study, we report a well conserved gene in nematodes of clade V and elucidate how this gene is involved in the molting process of the free-living nematode and the parasitic nematode . A predominant transcription of is detected in the larval stages of these worms, particularly in the molting process. Knockdown of this gene results in marked molecular changes of genes involved in cuticle synthesis and ecdysis, compromised shedding of the old cuticle, and reduced worm viability in . The crucial role of in molting is closely associated with a G protein beta subunit (GPB-1). Suppression of both and blocks shedding of the old cuticle, compromises the connection between the cuticle and hypodermis, and leads to an increased number of sick and dead worms, indicating essentiality of this module in nematode development and survival. These findings reveal the functional role of in nematode molting process and identify astacins as novel anthelmintic targets for parasitic nematodes of socioeconomic significance.
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http://dx.doi.org/10.3389/fcell.2021.695003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8313830PMC
July 2021

Acyl-CoA oxidase ACOX-1 interacts with a peroxin PEX-5 to play roles in larval development of Haemonchus contortus.

PLoS Pathog 2021 07 16;17(7):e1009767. Epub 2021 Jul 16.

Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, China.

Hypobiosis (facultative developmental arrest) is the most important life-cycle adaptation ensuring survival of parasitic nematodes under adverse conditions. Little is known about such survival mechanisms, although ascarosides (ascarylose with fatty acid-derived side chains) have been reported to mediate the formation of dauer larvae in the free-living nematode Caenorhabditis elegans. Here, we investigated the role of a key gene acox-1, in the larval development of Haemonchus contortus, one of the most important parasitic nematodes that employ hypobiosis as a routine survival mechanism. In this parasite, acox-1 encodes three proteins (ACOXs) that all show a fatty acid oxidation activity in vitro and in vivo, and interact with a peroxin PEX-5 in peroxisomes. In particular, a peroxisomal targeting signal type1 (PTS1) sequence is required for ACOX-1 to be recognised by PEX-5. Analyses on developmental transcription and tissue expression show that acox-1 is predominantly expressed in the intestine and hypodermis of H. contortus, particularly in the early larval stages in the environment and the arrested fourth larval stage within host animals. Knockdown of acox-1 and pex-5 in parasitic H. contortus shows that these genes play essential roles in the post-embryonic larval development and likely in the facultative arrest of this species. A comprehensive understanding of these genes and the associated β-oxidation cycle of fatty acids should provide novel insights into the developmental regulation of parasitic nematodes, and into the discovery of novel interventions for species of socioeconomic importance.
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http://dx.doi.org/10.1371/journal.ppat.1009767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8354476PMC
July 2021

The trypsin inhibitor-like domain is required for a serine protease inhibitor of Haemonchus contortus to inhibit host coagulation.

Int J Parasitol 2021 Jun 12. Epub 2021 Jun 12.

Institute of Preventive Veterinary Medicine, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, China. Electronic address:

Haemonchus contortus, a blood-feeding nematode, inhibits blood coagulation at the site of infection to facilitate blood-sucking and digesting for successful parasitism. However, the mechanism underlying anti-coagulation at the host-parasite interface is largely unknown. In the current study, Hc-spi-i8, which has two greatly different transcripts named Hc-spi-i8a and Hc-spi-i8b, respectively, was described. Hc-SPI-I8A was a serine protease inhibitor containing a trypsin inhibitor-like cysteine rich (TIL) domain, while Hc-SPI-I8B was not. Hc-SPI-I8A/B were primarily expressed in the hypodermis, intestines and gonads in the parasitic stages of H. contortus. Hc-SPI-I8A interacted with Ovis aries TSP1-containing protein (OaTSP1CP), which was determined by yeast two-hybrid, co-immunoprecipitation (Co-IP), pull down and co-localization experiments. The blood clotting time contributed by the TIL domain was prolonged by Hc-SPI-I8A. Hc-SPI-I8A is most likely interfering in the extrinsic coagulation cascade by interacting with OaTSP1CP through its TIL domain and intrinsic coagulation cascade by an unknown mechanism. These findings depict a crucial point in the host-parasite interaction during H. contortus colonization, which should contribute to drug discovery and vaccine development in fighting against this important parasite worldwide.
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http://dx.doi.org/10.1016/j.ijpara.2021.05.002DOI Listing
June 2021

Three Small Molecule Entities (MPK18, MPK334 and YAK308) with Activity against In Vitro.

Molecules 2021 May 10;26(9). Epub 2021 May 10.

Department of Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville 3010, Victoria, Australia.

Due to widespread multi-drug resistance in parasitic nematodes of livestock animals, there is an urgent need to discover new anthelmintics with distinct mechanisms of action. Extending previous work, here we screened a panel of 245 chemically-diverse small molecules for anti-parasitic activity against -an economically important parasitic nematode of livestock. This panel was screened in vitro against exsheathed third-stage larvae (xL3) of using an established phenotypic assay, and the potency of select compounds to inhibit larval motility and development assessed in dose-response assays. Of the 245 compounds screened, three-designated MPK18, MPK334 and YAK308-induced non-wildtype larval phenotypes and repeatedly inhibited xL3-motility, with IC values of 45.2 µM, 17.1 µM and 52.7 µM, respectively; two also inhibited larval development, with IC values of 12.3 µM (MPK334) and 6.5 µM (YAK308), and none of the three was toxic to human liver cells (HepG2). These findings suggest that these compounds deserve further evaluation as nematocidal candidates. Future work should focus on structure-activity relationship (SAR) studies of these chemical scaffolds, and assess the in vitro and in vivo efficacies and safety of optimised compounds against adults of .
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http://dx.doi.org/10.3390/molecules26092819DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8126080PMC
May 2021

Quantitative lipidomic analysis of Ascaris suum.

PLoS Negl Trop Dis 2020 12 2;14(12):e0008848. Epub 2020 Dec 2.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.

Ascaris is a soil-transmitted nematode that causes ascariasis, a neglected tropical disease affecting predominantly children and adolescents in the tropics and subtropics. Approximately 0.8 billion people are affected worldwide, equating to 0.86 million disability-adjusted life-years (DALYs). Exploring the molecular biology of Ascaris is important to gain a better understanding of the host-parasite interactions and disease processes, and supports the development of novel interventions. Although advances have been made in the genomics, transcriptomics and proteomics of Ascaris, its lipidome has received very limited attention. Lipidomics is an important sub-discipline of systems biology, focused on exploring lipids profiles in tissues and cells, and elucidating their biological and metabolic roles. Here, we characterised the lipidomes of key developmental stages and organ systems of Ascaris of porcine origin via high throughput LC-MS/MS. In total, > 500 lipid species belonging to 18 lipid classes within three lipid categories were identified and quantified-in precise molar amounts in relation to the dry weight of worm material-in different developmental stages/sexes and organ systems. The results showed substantial differences in the composition and abundance of lipids with key roles in cellular processes and functions (e.g. energy storage regulation and membrane structure) among distinct stages and among organ systems, likely reflecting differing demands for lipids, depending on stage of growth and development as well as the need to adapt to constantly changing environments within and outside of the host animal. This work provides the first step toward understanding the biology of lipids in Ascaris, with possibilities to work toward designing new interventions against ascariasis.
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http://dx.doi.org/10.1371/journal.pntd.0008848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7710092PMC
December 2020

Integrative genomic, proteomic and phenotypic studies of Leishmania donovani strains revealed genetic features associated with virulence and antimony-resistance.

Parasit Vectors 2020 Oct 12;13(1):510. Epub 2020 Oct 12.

Department of Pathogenic Biology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu, China.

Background: Leishmaniasis is a neglected tropical disease affecting millions of people worldwide. Emerging drug resistance of Leishmania species poses threaten to the effective control and elimination programme of this neglected tropical disease.

Methods: In this work, we conducted drug-resistance testing, whole genome resequencing and proteome profiling for a recently reported clinical isolate with supposed drug resistance (HCZ), and two reference sensitive strains (DD8 and 9044) of Leishmania donovani, to explore molecular mechanisms underlying drug resistance in this parasite.

Results: With reference to DD8 and 9044 strains, HCZ isolate showed higher-level virulence and clear resistance to antimonials in promastigote culture, infected macrophages and animal experiment. Pairwise genomic comparisons revealed genetic variations (86 copy number variations, 271 frameshift mutations in protein-coding genes and two site mutations in non-coding genes) in HCZ isolate that were absent from the reference sensitive strains. Proteomic analysis indicated different protein expression between HCZ isolate and reference strains, including 69 exclusively detected proteins and 82 consistently down-/upregulated molecules in the HCZ isolate. Integrative analysis showed linkage of 12 genomic variations (gene duplication, insertion and deletion) and their protein expression changes in HCZ isolate, which might be associated with pathogenic and antimony-resistant phenotype. Functional annotation analyses further indicated that molecules involved in nucleotide-binding, fatty acid metabolism, oxidation-reduction and transport might play a role in host-parasite interaction and drug-resistance.

Conclusions: This comprehensive integrative work provided novel insights into the genetic basis underlying virulence and resistance, suggesting new aspects to be investigated for a better intervention against L. donovani and associated diseases.
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http://dx.doi.org/10.1186/s13071-020-04397-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7552375PMC
October 2020

High-quality nuclear genome for Sarcoptes scabiei-A critical resource for a neglected parasite.

PLoS Negl Trop Dis 2020 10 1;14(10):e0008720. Epub 2020 Oct 1.

Cell and Molecular Biology Department, Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.

The parasitic mite Sarcoptes scabiei is an economically highly significant parasite of the skin of humans and animals worldwide. In humans, this mite causes a neglected tropical disease (NTD), called scabies. This disease results in major morbidity, disability, stigma and poverty globally and is often associated with secondary bacterial infections. Currently, anti-scabies treatments are not sufficiently effective, resistance to them is emerging and no vaccine is available. Here, we report the first high-quality genome and transcriptomic data for S. scabiei. The genome is 56.6 Mb in size, has a a repeat content of 10.6% and codes for 9,174 proteins. We explored key molecules involved in development, reproduction, host-parasite interactions, immunity and disease. The enhanced 'omic data sets for S. scabiei represent comprehensive and critical resources for genetic, functional genomic, metabolomic, phylogenetic, ecological and/or epidemiological investigations, and will underpin the design and development of new treatments, vaccines and/or diagnostic tests.
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http://dx.doi.org/10.1371/journal.pntd.0008720DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7591027PMC
October 2020

Toward integrative 'omics of the barber's pole worm and related parasitic nematodes.

Infect Genet Evol 2020 11 11;85:104500. Epub 2020 Aug 11.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia. Electronic address:

Advances in nucleic acid sequencing, mass spectrometry and computational biology have facilitated the identification, annotation and analysis of genes, transcripts, proteins and metabolites in model nematodes (Caenorhabditis elegans and Pristionchus pacificus) and socioeconomically important parasitic nematodes (Clades I, III, IV and V). Significant progress has been made in genomics and transcriptomics as well as in the proteomics and lipidomics of Haemonchus contortus (the barber's pole worm) - one of the most pathogenic representatives of the order Strongylida. Here, we review salient aspects of genomics, transcriptomics, proteomics, lipidomics, glycomics and functional genomics, and discuss the rise of integrative 'omics of this economically important parasite. Although our knowledge of the molecular biology, genetics and biochemistry of H. contortus and related species has progressed significantly, much remains to be explored, particularly in areas such as drug resistance, unique/unknown genes, host-parasite interactions, parasitism and the pathogenesis of disease, by integrating the use of multiple 'omics methods. This approach should lead to a better understanding of H. contortus and its relatives at a 'systems biology' level, and should assist in developing new interventions against these parasites.
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http://dx.doi.org/10.1016/j.meegid.2020.104500DOI Listing
November 2020

Natural Compounds from the Marine Brown Alga with Potent In Vitro-Activity against the Parasitic Nematode .

Pathogens 2020 Jul 9;9(7). Epub 2020 Jul 9.

Department of Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.

Eight secondary metabolites ( to ) were isolated from a marine sponge, a marine alga and three terrestrial plants collected in Australia and subsequently chemically characterised. Here, these natural product-derived compounds were screened for in vitro-anthelmintic activity against the larvae and adult stages of (barber's pole worm)-a highly pathogenic parasitic nematode of ruminants. Using an optimised, whole-organism screening system, compounds were tested on exsheathed third-stage larvae (xL3s) and fourth-stage larvae (L4s). Anthelmintic activity was initially evaluated on these stages based on the inhibition of motility, development and/or changes in morphology (phenotype). We identified two compounds, 6-undecylsalicylic acid () and 6-tridecylsalicylic acid () isolated from the marine brown alga, with inhibitory effects on xL3 and L4 motility and larval development, and the induction of a "skinny-straight" phenotype. Subsequent testing showed that these two compounds had an acute nematocidal effect (within 1-12 h) on adult males and females of . Ultrastructural analysis of adult worms treated with compound revealed significant damage to subcuticular musculature and associated tissues and cellular organelles including mitochondria. In conclusion, the present study has discovered two algal compounds possessing acute anthelmintic effects and with potential for hit-to-lead progression. Future work should focus on undertaking a structure-activity relationship study and on elucidating the mode(s) of action of optimised compounds.
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http://dx.doi.org/10.3390/pathogens9070550DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400099PMC
July 2020

Lipid composition and abundance in the reproductive and alimentary tracts of female Haemonchus contortus.

Parasit Vectors 2020 Jul 6;13(1):338. Epub 2020 Jul 6.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.

Background: Lipids play essential structural and functional roles in the biology of animals. Studying the composition and abundance of lipids in parasites should assist in gaining a better understanding of their molecular biology, biochemistry and host-parasite interactions.

Methods: Here, we used a combination of high-performance liquid chromatography and mass spectrometric analyses, combined with bioinformatics, to explore the lipid composition and abundance in the reproductive (Rt) and alimentary (At) tracts of Haemonchus contortus.

Results: We identified and quantified 320 unique lipid species representing four categories: glycerolipids, glycerophospholipids, sphingolipids and steroid lipids. Glycerolipids (i.e. triradylglycerols) and glycerophospholipids (i.e. glycerophosphocholines) were the most commonly and abundant lipid classes identified and were significantly enriched in Rt and At, respectively. We propose that select parasite-derived lipids in Rt and At of adult female H. contortus are required as an energy source (i.e. triradylglycerol) or are involved in phospholipid biosynthesis (i.e. incorporated fatty acids) and host-parasite interactions (i.e. phospholipids and lysophospholipids).

Conclusions: This work provides a first foundation to explore lipids at the organ-specific and tissue-specific levels in nematodes, and to start to unravel aspects of lipid transport, synthesis and metabolism, with a perspective on discovering new intervention targets.
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http://dx.doi.org/10.1186/s13071-020-04208-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339462PMC
July 2020

Global prevalence of Toxocara infection in cats.

Adv Parasitol 2020 25;109:615-639. Epub 2020 Apr 25.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia. Electronic address:

Zoonotic parasites, including Toxocara species, of pet and stray cats are of public health importance. Justification for, and the design and implementation of prevention and control of human toxocariasis may benefit from an understanding of the zoonotic potential and prevalence of parasites in this definitive host species. This is the first systematic review and meta-analysis of cross-sectional studies, conducted to estimate the prevalence of Toxocara infection(s) in cats by geographical location, type (rural vs urban and stray vs pet), gender and age. Pooled data were assessed using a random effects-model as well as several meta-regression and stratified analyses conducted. Of 1733 peer-reviewed articles, 143 were included in this review and represented 2,158,069 cats from 51 countries. The global pooled (95% CI) prevalence of Toxocara infection in cats was 17.0% (16.1-17.8%), being highest in African (43.3%, 28.3-58.4%) and lowest in South American (12.6%, 8.2-17.0%) countries. In other WHO regions, prevalence rates of Toxocara were as follows: Eastern Mediterranean (21.6%, 15.1-28.1%), North America (18.3%, 15.4-21.2%), Europe (17.8%, 15.9-19.7%), Western Pacific (17.3%, 14.7-19.9%), and South-East Asia (14.9%, 9.8-20.1%). Prevalence of Toxocara was higher in low-income tropical countries and also in stray (28.6%, 25.1-32.1%) and young (≤12 months of age) (27.7%, 23.4-32.0%) cats than in pet (11.6%, 10.7-12.5%) and older cats (>12 months of age) (23.8%, 14.8-32.7%). This review indicates that ~118-150 million cats worldwide serve as definitive hosts of Toxocara, shedding eggs and thus contributing to the public health risk of human infection. Prevention and control of this zoonosis in cats should receive greater attention by health officials and cat owners, particularly in countries where risk factors and prevalence are highest.
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http://dx.doi.org/10.1016/bs.apar.2020.01.025DOI Listing
May 2021

Global prevalence of Toxocara infection in dogs.

Adv Parasitol 2020 26;109:561-583. Epub 2020 Feb 26.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia. Electronic address:

Dogs serve as the most important definitive hosts for Toxocara canis-a causative agent of human toxocariasis and one of the most widespread zoonotic helminth worldwide. The present study was undertaken to assess the global prevalence of T. canis infection in dogs. PubMed, Scopus, Web of Science, EMBASE and SciELO were searched to identify relevant studies. A random-effects model was used to estimate the overall and the subgroup-pooled prevalences across studies, and heterogeneity was assessed via the I test. The data were categorized according to WHO-region, different types of dogs, risk factors and environmental variables. From a total of 4370 peer-reviewed publications, 229 articles that studied 13,010,004 dogs in 60 countries met the final inclusion criteria. The overall prevalence of Toxocara infection in dogs was 11.1% (95% CI, 10.6-11.7%). The estimated prevalence in the different WHO-regions ranged from 6.4% to 19.2%: Eastern Mediterranean (19.2%, 13.7-25.5%), Africa (18.5%, 13.7-23.9%), South-East Asia (11.9%, 6.8-18.2%), North America (11.1%, 10.6-11.7%), South America (10.9%, 7.6-14.6%), Europe (10.8%, 8.9-12.9%) and Western Pacific (6.4%, 3.3-10.2%). Young (<1 year of age), stray, rural and male dogs had a significantly (P<0.001) higher prevalence of infection than older, pet, urban or female dogs. The prevalence was higher in low income countries and regions at a low geographical latitude, close to the equator, characterized as having tropical climates. From this review, it is estimated that ≥100 million dogs are infected with Toxocara around the world. This highlights the need for an increased focus on implementing affordable, appropriate control programs to reduce the public health threat of toxocariasis as a zoonosis of global importance.
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http://dx.doi.org/10.1016/bs.apar.2020.01.017DOI Listing
May 2021

Global and regional seroprevalence estimates for human toxocariasis: A call for action.

Adv Parasitol 2020 25;109:275-290. Epub 2020 Apr 25.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia. Electronic address:

Human toxocariasis is a parasitic disease transmitted usually from dogs and/or cats that are infected with Toxocara species, and can be associated with a range of allergic, neurological and/or visual disorders. Recent epidemiological research has estimated that ~1.4 billion people worldwide, particularly in subtropical and tropical regions, are infected with, or exposed to Toxocara species, indicating that human toxocariasis is a neglected tropical disease. Here, we review recent research efforts, consider risk factors, discuss limitations in current seroprevalence estimates, and propose some future research directions towards improved awareness, surveillance, prevention and control of this neglected disease.
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http://dx.doi.org/10.1016/bs.apar.2020.01.011DOI Listing
May 2021

Synthetic Kavalactone Analogues with Increased Potency and Selective Anthelmintic Activity against Larvae of In Vitro.

Molecules 2020 Apr 24;25(8). Epub 2020 Apr 24.

Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.

Kava extract, an aqueous rhizome emulsion of the plant , has been used for centuries by Pacific Islanders as a ceremonial beverage, and has been sold as an anxiolytic agent for some decades. Kavalactones are a major constituent of kava extract. In a previous investigation, we had identified three kavalactones that inhibit larval development of in an in vitro-bioassay. In the present study, we synthesized two kavalactones, desmethoxyyangonin and yangonin, as well as 17 analogues thereof, and evaluated their anthelmintic activities using the same bioassay as employed previously. Structure activity relationship (SAR) studies showed that a 4-substituent on the pendant aryl ring was required for activity. In particular, compounds with 4-trifluoromethoxy, 4-difluoromethoxy, 4-phenoxy, and 4--morpholine substitutions had anthelmintic activities (IC values in the range of 1.9 to 8.9 µM) that were greater than either of the parent natural products-desmethoxyyangonin (IC of 37.1 µM) and yangonin (IC of 15.0 µM). The synthesized analogues did not exhibit toxicity on HepG2 human hepatoma cells in vitro at concentrations of up to 40 µM. These findings confirm the previously-identified kavalactone scaffold as a promising chemotype for new anthelmintics and provide a basis for a detailed SAR investigation focused on developing a novel anthelmintic agent.
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http://dx.doi.org/10.3390/molecules25082004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7221733PMC
April 2020

Elucidating the molecular and developmental biology of parasitic nematodes: Moving to a multiomics paradigm.

Adv Parasitol 2020 31;108:175-229. Epub 2020 Jan 31.

The University of Melbourne, Parkville, VIC, Australia. Electronic address:

In the past two decades, significant progress has been made in the sequencing, assembly, annotation and analyses of genomes and transcriptomes of parasitic worms of socioeconomic importance. This progress has somewhat improved our knowledge and understanding of these pathogens at the molecular level. However, compared with the free-living nematode Caenorhabditis elegans, the areas of functional genomics, transcriptomics, proteomics and metabolomics of parasitic nematodes are still in their infancy, and there are major gaps in our knowledge and understanding of the molecular biology of parasitic nematodes. The information on signalling molecules, molecular pathways and microRNAs (miRNAs) that are known to be involved in developmental processes in C. elegans and the availability of some molecular resources (draft genomes, transcriptomes and some proteomes) for selected parasitic nematodes provide a basis to start exploring the developmental biology of parasitic nematodes. Indeed, some studies have identified molecules and pathways that might associate with developmental processes in related, parasitic nematodes, such as Haemonchus contortus (barber's pole worm). However, detailed information is often scant and 'omics resources are limited, preventing a proper integration of 'omic data sets and comprehensive analyses. Moreover, little is known about the functional roles of pheromones, hormones, signalling pathways and post-transcriptional/post-translational regulations in the development of key parasitic nematodes throughout their entire life cycles. Although C. elegans is an excellent model to assist molecular studies of parasitic nematodes, its use is limited when it comes to explorations of processes that are specific to parasitism within host animals. A deep understanding of parasitic nematodes, such as H. contortus, requires substantially enhanced resources and the use of integrative 'omics approaches for analyses. The improved genome and well-established in vitro larval culture system for H. contortus provide unprecedented opportunities for comprehensive studies of the transcriptomes (mRNA and miRNA), proteomes (somatic, excretory/secretory and phosphorylated proteins) and lipidomes (e.g., polar and neutral lipids) of this nematode. Such resources should enable in-depth explorations of its developmental biology at a level, not previously possible. The main aims of this review are (i) to provide a background on the development of nematodes, with a particular emphasis on the molecular aspects involved in the dauer formation and exit in C. elegans; (ii) to critically appraise the current state of knowledge of the developmental biology of parasitic nematodes and identify key knowledge gaps; (iii) to cover salient aspects of H. contortus, with a focus on the recent advances in genomics, transcriptomics, proteomics and lipidomics as well as in vitro culturing systems; (iv) to review recent advances in our knowledge and understanding of the molecular and developmental biology of H. contortus using an integrative multiomics approach, and discuss the implications of this approach for detailed explorations of signalling molecules, molecular processes and pathways likely associated with nematode development, adaptation and parasitism, and for the identification of novel intervention targets against these pathogens. Clearly, the multiomics approach established recently is readily applicable to exploring a wide range of interesting and socioeconomically significant parasitic worms (including also trematodes and cestodes) at the molecular level, and to elucidate host-parasite interactions and disease processes.
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http://dx.doi.org/10.1016/bs.apar.2019.12.005DOI Listing
July 2020

High anti-Ascaris seroprevalence in fattening pigs in Sichuan, China, calls for improved management strategies.

Parasit Vectors 2020 Feb 12;13(1):60. Epub 2020 Feb 12.

Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia.

Background: Ascariasis, caused by Ascaris suum, is an important soil-transmitted parasitic disease of pigs worldwide. It leads to significant economic losses in the pork industry, as a consequence of low feed conversion efficiency in pigs and liver condemnation at slaughter. Despite ascariasis still being widespread on pig farms in many developing and the industrialised countries, there are surprisingly limited data on porcine ascariasis in China, where nearly half of the world's total pork is produced.

Methods: In the present study, using the recently developed A. suum-haemoglobin (As-Hb) antigen-based serological test, we screened 512 individual serum samples from fattening pigs from 13 farms across seven distinct locations of Sichuan Province in China for anti-Ascaris antibody.

Results: The prevalence of anti-Ascaris antibody ranged from 0% to 100% on the distinct farms, with the mean (overall) seroprevalence being > 60%. There was no significant difference in seroprevalence between the intensive and extensive farms.

Conclusions: To our knowledge, this is the first study to measure anti-Ascaris seroprevalence in China. The results of this 'snapshot' investigation indicate that Ascaris infection in commercial pig farms in Sichuan Province is seriously underestimated, encouraging future, large-scale serological studies to assess the distribution and extent of Ascaris exposure and infection in various regions of China and the world.
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http://dx.doi.org/10.1186/s13071-020-3935-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017502PMC
February 2020

The developmental phosphoproteome of Haemonchus contortus.

J Proteomics 2020 02 14;213:103615. Epub 2019 Dec 14.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

Protein phosphorylation plays essential roles in many cellular processes. Despite recent progress in the genomics, transcriptomics and proteomics of socioeconomically important parasitic nematodes, there is scant phosphoproteomic data to underpin molecular biological discovery. Here, using the phosphopeptide enrichment-based LC-MS/MS and data-independent acquisition (DIA) quantitation, we characterised the first developmental phosphoproteome of the parasitic nematode Haemonchus contortus - one of the most pathogenic parasites of ruminant livestock. Totally, 1804 phosphorylated proteins with 4406 phosphorylation sites ('phosphosites') from different developmental stages/sexes were identified. Bioinformatic analyses of quantified 'phosphosites' exhibited distinctive stage- and sex-specific patterns during development, and identified a subset of phosphoproteins proposed to play crucial roles in processes such as spindle positioning, signal transduction and kinase activity. A sequence-based comparison of the phosphoproteome of H. contortus with those of two free-living nematode species (Caenorhabditis elegans and Pristionchus pacificus) suggested a limited number of common protein phosphorylation events among these species. Our findings infer active roles for protein phosphorylation in the adaptation of a parasitic nematode to a constantly changing external environment. The phosphoproteomic data set for H. contortus provides a basis to better understand phosphorylation and associated biological processes (e.g., regulation of signal transduction), and might enable the discovery of novel anthelmintic targets. SIGNIFICANCE: Here, we report the first phosphoproteome for a socioeconomically parasitic nematode (Haemonchus contortus). This phosphoproteome exhibits distinctive patterns during development, suggesting active roles of post-translational modification in the parasite's adaptation to changing environments within and outside of the host animal. This work sheds a light on the developmental phosphorylation in a parasitic nematode, and could enable the discovery of novel interventions against major pathogens.
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http://dx.doi.org/10.1016/j.jprot.2019.103615DOI Listing
February 2020

Human toxocariasis - A look at a neglected disease through an epidemiological 'prism'.

Infect Genet Evol 2019 10 11;74:104002. Epub 2019 Aug 11.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia. Electronic address:

Toxocariasis, a disease caused by infection with larvae of Toxocara canis, T. cati and/or congeners, represents clinical syndromes in humans including visceral and ocular larva migrans, neurotoxocariasis and covert/common toxocariasis. It is reported to be one of the most widespread public health and economically important zoonotic parasitic infections that humans share with dogs, wild canids, including foxes, and possibly other mammals. Humans become infected by accidental ingestion of embryonated Toxocara eggs, or larvae from tissues from domestic or wild paratenic hosts. Most infections are asymptomatic, and human disease may go unnoticed, as clinical investigation is often not pursued and/or diagnostic testing not conducted. Sometimes toxocariasis can be associated with complications, such as allergic and/or neurological disorders, possibly including cognitive or developmental delays in children. There is no anti-toxocariasis vaccine, and chemotherapy in humans varies, depending on symptoms and location of larvae, and may include the administration of albendazole or mebendazole, together with anti-inflammatory corticosteroids. Some recent studies indicate that toxocariasis is having an increased, adverse impact on human health in some, particularly underprivileged, tropical and subtropical communities around the world. Although tens of millions of people, especially children, are expected to be exposed to, or infected with Toxocara species, there is limited precise epidemiological data or information on the relationship between seropositivity and disease (toxocariasis) on a global scale. To gain an improved insight into this area, the present article reviews salient clinical aspects of human toxocariasis and the epidemiology of this disease, with particular reference to seroprevalence, and discusses future research and approaches/measures to understand and prevent/control this socioeconomically important, yet neglected zoonosis.
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http://dx.doi.org/10.1016/j.meegid.2019.104002DOI Listing
October 2019

Dafachronic acid promotes larval development in Haemonchus contortus by modulating dauer signalling and lipid metabolism.

PLoS Pathog 2019 07 23;15(7):e1007960. Epub 2019 Jul 23.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia.

Here, we discovered an endogenous dafachronic acid (DA) in the socioeconomically important parasitic nematode Haemonchus contortus. We demonstrate that DA promotes larval exsheathment and development in this nematode via a relatively conserved nuclear hormone receptor (DAF-12). This stimulatory effect is dose- and time-dependent, and relates to a modulation of dauer-like signalling, and glycerolipid and glycerophospholipid metabolism, likely via a negative feedback loop. Specific chemical inhibition of DAF-9 (cytochrome P450) was shown to significantly reduce the amount of endogenous DA in H. contortus; compromise both larval exsheathment and development in vitro; and modulate lipid metabolism. Taken together, this evidence shows that DA plays a key functional role in the developmental transition from the free-living to the parasitic stage of H. contortus by modulating the dauer-like signalling pathway and lipid metabolism. Understanding the intricacies of the DA-DAF-12 system and associated networks in H. contortus and related parasitic nematodes could pave the way to new, nematode-specific treatments.
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http://dx.doi.org/10.1371/journal.ppat.1007960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6677322PMC
July 2019

Aquaporin 1 is located on the intestinal basolateral membrane in Toxocara canis and might play a role in drug uptake.

Parasit Vectors 2019 May 17;12(1):243. Epub 2019 May 17.

Department of Veterinary Medicine, College of Animal Science, Southwest University, Chongqing, 402460, The People's Republic of China.

Background: Aquaporins (AQPs) are a family of integral membrane channel proteins that facilitate the transport of water and other small solutes across cell membranes. AQPs appear to play crucial roles in parasite survival and represent possible drug targets for novel intervention strategy. In this work, we investigated the tissue distribution and biological roles of an aquaporin TcAQP1 in the neglected parasitic nematode Toxocara canis.

Methods: Recombinant C-terminal hydrophilic domain of AQP1 of T. canis (rTcAQP1c) and polyclonal antibody against rTcAQP1c were produced to analyse the tissue expression of native TcAQP1 in adult (female and male) worms using an immunohistochemical approach. RNA interference (RNAi), quantitative real-time PCR (qRT-PCR) and nematocidal assays were performed to investigate the functional roles of TcAQP1 in the adult stage of T. canis.

Results: Immunofluorescence analysis showed that TcAQP1 was localised predominantly in the epithelial linings of the reproductive tract and basolateral membrane of the intestine in the adult stage (female and male) of T. canis, indicating important roles in reproduction, nutrient absorption and/or osmoregulation. Treatment with silencing RNA for 24 h resulted in a significant reduction of Tc-aqp-1 mRNA level in adult T. canis, though no phenotypical change was observed. The efficient gene knockdown compromised the nematocidal activity of albendazole in vitro, suggesting the role of TcAQP1 in drug uptake.

Conclusions: The findings of this study provide important information about tissue expression and functional roles of TcAQP1 protein in adult T. canis. Understanding the biological functions of this protein in other developmental stages of T. canis and related parasitic nematodes would contribute to the discovery of novel diagnostic or anthelmintic targets.
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http://dx.doi.org/10.1186/s13071-019-3500-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6525457PMC
May 2019

High throughput LC-MS/MS-based proteomic analysis of excretory-secretory products from short-term in vitro culture of Haemonchus contortus.

J Proteomics 2019 07 6;204:103375. Epub 2019 May 6.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

Parasitic nematodes of humans, animals and plants have a major, adverse impact on global health and agricultural production worldwide. To cope with their surrounding environment in and the immune attack from the host, excretory-secretory (ES) proteins are released by nematodes to orchestrate or regulate parasite-host interactions. In the present study, we characterised the ES products from short-term (12 h) in vitro culture of different developmental stages/sexes of Haemonchus contortus (one of the most important parasitic nematodes of livestock animals worldwide) using a high throughput tandem mass-spectrometry, underpinned by the most recent genomic dataset. In total, 878 unique proteins from key developmental stages/sexes (third-stage and fourth-stage larvae, and female and male adults) were identified and quantified with high confidence. Bioinformatic analyses showed noteworthy ES protein alterations during the transition from the free-living to the parasitic phase, especially for proteins which are likely involved in nutrient digestion and acquisition as well as parasite-host interactions, such as proteolytic cascade-related peptidases, glycoside hydrolases, C-type lectins and sperm-coating protein/Tpx/antigen 5/pathogenesis related-1/Sc7 (= SCP/TAPS) proteins. Our findings provide an avenue to better explore interactive processes between the host and this highly significant parasitic nematode, to underpin the search for novel drug and vaccine targets. SIGNIFICANCE: The present study represents a comprehensive proteomic analysis of the secretome of key developmental stages/sexes of H. contortus maintained in short-term in vitro culture. High throughput LC-MS/MS analysis of ES products allowed the identification of a large repertoire of proteins (secretome) and the establishment of a new proteomic database for H. contortus. The secretome of H. contortus undergoes substantial changes during the nematode's transition from free-living to parasitic stages, suggesting a constant adaptation to different environments outside of and within the host animal. Understanding the host-parasite relationship at the molecular level could assist significantly in the development of intervention strategies (i.e. novel drugs and vaccines) against H. contortus and related nematodes.
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http://dx.doi.org/10.1016/j.jprot.2019.05.003DOI Listing
July 2019

Dauer signalling pathway model for Haemonchus contortus.

Parasit Vectors 2019 Apr 29;12(1):187. Epub 2019 Apr 29.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC, 3010, Australia.

Background: Signalling pathways have been extensively investigated in the free-living nematode Caenorhabditis elegans, but very little is known about these pathways in parasitic nematodes. Here, we constructed a model for the dauer-associated signalling pathways in an economically highly significant parasitic worm, Haemonchus contortus.

Methods: Guided by data and information available for C. elegans, we used extensive genomic and transcriptomic datasets to infer gene homologues in the dauer-associated pathways, explore developmental transcriptomic, proteomic and phosphoproteomic profiles in H. contortus and study selected molecular structures.

Results: The canonical cyclic guanosine monophosphate (cGMP), transforming growth factor-β (TGF-β), insulin-like growth factor 1 (IGF-1) and steroid hormone signalling pathways of H. contortus were inferred to represent a total of 61 gene homologues. Compared with C. elegans, H. contortus has a reduced set of genes encoding insulin-like peptides, implying evolutionary and biological divergences between the parasitic and free-living nematodes. Similar transcription profiles were found for all gene homologues between the infective stage of H. contortus and dauer stage of C. elegans. High transcriptional levels for genes encoding G protein-coupled receptors (GPCRs), TGF-β, insulin-like ligands (e.g. ins-1, ins-17 and ins-18) and transcriptional factors (e.g. daf-16) in the infective L3 stage of H. contortus were suggestive of critical functional roles in this stage. Conspicuous protein expression patterns and extensive phosphorylation of some components of these pathways suggested marked post-translational modifications also in the L3 stage. The high structural similarity in the DAF-12 ligand binding domain among nematodes indicated functional conservation in steroid (i.e. dafachronic acid) signalling linked to worm development.

Conclusions: Taken together, this pathway model provides a basis to explore hypotheses regarding biological processes and regulatory mechanisms (via particular microRNAs, phosphorylation events and/or lipids) associated with the development of H. contortus and related nematodes as well as parasite-host cross talk, which could aid the discovery of new therapeutic targets.
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http://dx.doi.org/10.1186/s13071-019-3419-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6489264PMC
April 2019

Somatic proteome of Haemonchus contortus.

Int J Parasitol 2019 03 14;49(3-4):311-320. Epub 2019 Feb 14.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

Currently, there is a dearth of proteomic data to underpin fundamental investigations of parasites and parasitism at the molecular level. Here, using a high throughput LC-MS/MS-based approach, we undertook the first reported comprehensive, large-scale proteomic investigation of the barber's pole worm (Haemonchus contortus) - one of the most important parasitic nematodes of livestock animals worldwide. In total, 2487 unique H. contortus proteins representing different developmental stages/sexes (i.e. eggs, L3s and L4s, female (Af) and male (Am) adults) were identified and quantified with high confidence. Bioinformatic analyses of this proteome revealed substantial alterations in protein profiles during the life cycle, particularly in the transition from the free-living to the parasitic phase, and key groups of proteins involved specifically in feeding, digestion, metabolism, development, parasite-host interactions (including immunomodulation), structural remodelling of the body wall and adaptive processes during parasitism. This proteomic data set will facilitate future molecular, biochemical and physiological investigations of H. contortus and related nematodes, and the discovery of novel intervention targets against haemonchosis.
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http://dx.doi.org/10.1016/j.ijpara.2018.12.003DOI Listing
March 2019

Comparative bioinformatic analysis suggests that specific dauer-like signalling pathway components regulate Toxocara canis development and migration in the mammalian host.

Parasit Vectors 2019 Jan 14;12(1):32. Epub 2019 Jan 14.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia.

Background: Toxocara canis is quite closely related to Ascaris suum but its biology is more complex, involving a phase of arrested development (diapause or hypobiosis) in tissues as well as transplacental and transmammary transmission routes. In the present study, we explored and compared dauer-like signalling pathways of T. canis and A. suum to infer which components in these pathways might associate with, or regulate, this added complexity in T. canis.

Methods: Guided by information for Caenorhabditis elegans, we bioinformatically inferred and compared components of dauer-like signalling pathways in T. canis and A. suum using genomic and transcriptomic data sets. In these two ascaridoids, we also explored endogenous dafachronic acids (DAs), which are known to be critical in regulating larval developmental processes in C. elegans and other nematodes, by liquid chromatography-mass spectrometry (LC-MS).

Results: Orthologues of C. elegans dauer signalling genes were identified in T. canis (n = 55) and A. suum (n = 51), inferring the presence of a dauer-like signalling pathway in both species. Comparisons showed clear differences between C. elegans and these ascaridoids as well as between T. canis and A. suum, particularly in the transforming growth factor-β (TGF-β) and insulin-like signalling pathways. Specifically, in both A. suum and T. canis, there was a paucity of genes encoding SMAD transcription factor-related protein (daf-3, daf-5, daf-8 and daf-14) and insulin/insulin-like peptide (daf-28, ins-4, ins-6 and ins-7) homologues, suggesting an evolution and adaptation of the signalling pathway in these parasites. In T. canis, there were more orthologues coding for homologues of antagonist insulin-like peptides (Tc-ins-1 and Tc-ins-18), an insulin receptor substrate (Tc-ist-1) and a serine/threonine kinase (Tc-akt-1) than in A. suum, suggesting potentiated functional roles for these molecules in regulating larval diapause and reactivation. A relatively conserved machinery was proposed for DA synthesis in the two ascaridoids, and endogenous Δ4- and Δ7-DAs were detected in them by LC-MS analysis. Differential transcription analysis between T. canis and A. suum suggests that ins-17 and ins-18 homologues are specifically involved in regulating development and migration in T. canis larvae in host tissues.

Conclusion: The findings of this study provide a basis for functional explorations of insulin-like peptides, signalling hormones (i.e. DAs) and related nuclear receptors, proposed to link to development and/or parasite-host interactions in T. canis. Elucidating the functional roles of these molecules might contribute to the discovery of novel anthelmintic targets in ascaridoids.
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http://dx.doi.org/10.1186/s13071-018-3265-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6332619PMC
January 2019

The developmental lipidome of Haemonchus contortus.

Int J Parasitol 2018 10 1;48(12):887-895. Epub 2018 Sep 1.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

Lipids play crucial roles in the biology of organisms, particularly relating to cellular membranes, energy storage, and intra- or inter-cellular signalling. Despite the recent expansion of the lipidomics field, very little is known about the biology of lipids in metzoan pathogens, and, to date, there has been no global lipidomic study of a parasitic nematode. Using Haemonchus contortus (barber's pole worm) as a model, we describe the first known global lipidome for a parasitic nematode via high throughput LC-MS/MS-based lipidomics. We identified a total of 554 lipid species across four lipid categories, and 18 lipid classes exhibited alterations among six developmental stages (eggs; L3 and exsheathed L3 (xL3) and L4 larval stages; female and male adults) of H. contortus. The lipid composition and abundance of H. contortus changed significantly during the transition from free-living (egg, L3 and xL3) to parasitic (L4 and adult) stages. The three main changes observed were: (i) decreased synthesis of triradylglycerols; (ii) increased glycerophospholipids (predominantly glycerophosphoethanolamines and glycerophosphocholines); and (iii) a 'cooperative' modulation of ether-linked lipids and saturated fatty acids. These changes suggest specific adaptations, in terms of nutrient acquisition, metabolism and development, as the nematode makes its transition to the parasitic stage inside the host animal. This lipidomic data set serves as a stimulus for studies to understand lipid biology in parasitic worms, and their roles in parasite-host interactions and disease processes.
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http://dx.doi.org/10.1016/j.ijpara.2018.06.002DOI Listing
October 2018

Molecular alterations during larval development of Haemonchus contortus in vitro are under tight post-transcriptional control.

Int J Parasitol 2018 08 22;48(9-10):763-772. Epub 2018 May 22.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

In this study, we explored the molecular alterations in the developmental switch from the L3 to the exsheathed L3 (xL3) and to the L4 stage of Haemonchus contortus in vitro using an integrated transcriptomic, proteomic and bioinformatic approach. Totals of 9,754 mRNAs, 88 microRNAs (miRNAs) and 1,591 proteins were identified, and 6,686 miRNA-mRNA pairs inferred in all larval stages studied. Approximately 16% of transcripts in the combined transcriptome (representing all three larval stages) were expressed as proteins, and there were positive correlations (r = 0.39-0.44) between mRNA transcription and protein expression in the three distinct developmental stages of the parasite. Of the predicted targets, 1,019 (27.0%) mRNA transcripts were expressed as proteins, and there was a negative correlation (r = -0.60 to -0.50) in the differential mRNA transcription and protein expression between developmental stages upon pairwise comparison. The changes in transcription (mRNA and miRNA) and protein expression from the free-living to the parasitic life cycle phase of H. contortus related to enrichments in biological pathways associated with metabolism (e.g., carbohydrate and lipid degradation, and amino acid metabolism), environmental information processing (e.g., signal transduction, signalling molecules and interactions) and/or genetic information processing (e.g., transcription and translation). Specifically, fatty acid degradation, steroid hormone biosynthesis and the Rap1 signalling pathway were suppressed, whereas transcription, translation and protein processing in the endoplasmic reticulum were upregulated during the transition from the free-living L3 to the parasitic xL3 and L4 stages of the nematode in vitro. Dominant post-transcriptional regulation was inferred to elicit these changes, and particular miRNAs (e.g., hco-miR-34 and hco-miR-252) appear to play roles in stress responses and/or environmental adaptations during developmental transitions of H. contortus. Taken together, these integrated results provide a comprehensive insight into the developmental biology of this important parasite at the molecular level in vitro. The approach applied here to H. contortus can be readily applied to other parasitic nematodes.
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http://dx.doi.org/10.1016/j.ijpara.2018.03.008DOI Listing
August 2018

Human toxocariasis.

Lancet Infect Dis 2018 01 3;18(1):e14-e24. Epub 2017 Aug 3.

Department of Veterinary Biosciences, Melbourne Veterinary School, The University of Melbourne, Parkville, VIC, Australia. Electronic address:

Parasitic nematodes of the genus Toxocara are socioeconomically important zoonotic pathogens. These parasites are usually directly transmitted to the human host via the faecal-oral route and can cause toxocariasis and associated complications, including allergic and neurological disorders. Although tens of millions of people are estimated to be exposed to or infected with Toxocara spp, global epidemiological information on the relationship between seropositivity and toxocariasis is limited. Recent findings suggest that the effect of toxocariasis on human health is increasing in some countries. Here we review the salient background on Toxocara and biology, summarise key aspects of the pathogenesis, diagnosis, and treatment of toxocariasis, describe what is known about its geographic distribution and prevalence, and make some recommendations for future research towards the prevention and control of this important disease.
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http://dx.doi.org/10.1016/S1473-3099(17)30331-6DOI Listing
January 2018

First survey of Cryptosporidium, Giardia and Enterocytozoon in diarrhoeic children from Wuhan, China.

Infect Genet Evol 2017 07 8;51:127-131. Epub 2017 Mar 8.

State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia. Electronic address:

Intestinal protozoan pathogens cause significant diarrhoeal diseases in children. However, to date, there has been limited genetic study of the intestinal pathogens Cryptosporidium, Giardia and Enterocytozoon in humans in China, with the exception of research in a small number of cities/provinces. In the present study, PCR-based tools were used to detect and characterise these protistan parasites from 500 children with a history of diarrhoea in Wuhan and environs, Hubei province, China. Genomic DNAs from faecal samples were screened for the particular protists by PCR utilising regions in the small subunit (SSU) of the nuclear ribosomal RNA, the 60kDa glycoprotein (gp60), the internal transcribed spacer of nuclear ribosomal DNA (ITS) and/or the triose phosphate isomerase (tpi) genes as markers. Cryptosporidium meleagridis subtype IIIb (10/500, 2.0%), Giardia duodenalis assemblage A (7/500, 1.4%) and Enterocytozoon bieneusi genotype D (1/500, 0.2%) were identified in small percentages of the 500 samples. No significant gender- or age-associated differences in the prevalence of Cryptosporidium and Giardia infections were found. Future studies might focus on the occurrence of these protists in children as well as animals, with an emphasis on Cryptosporidium meleagridis in pets and agriculturally important birds, in different parts of Hubei province.
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http://dx.doi.org/10.1016/j.meegid.2017.03.006DOI Listing
July 2017

MicroRNAs of Toxocara canis and their predicted functional roles.

Parasit Vectors 2016 Apr 23;9:229. Epub 2016 Apr 23.

Department of Veterinary Medicine, Rongchang Campus of Southwest University, Chongqing, 402460, The People's Republic of China.

Background: Toxocara canis is the causative agent of toxocariasis of humans and other animals. This parasitic nematode (roundworm) has a complex life cycle, in which substantial developmental changes and switches occur. As small non-coding RNAs (sRNAs) are key regulators of gene expression in a wide range of organisms, we explored these RNAs in T. canis to provide a basis for future studies of its developmental biology as well as host interactions and disease at the molecular level.

Methods: We conducted high-throughput RNA sequencing and bioinformatic analyses to define sRNAs in individual male and female adults of T. canis.

Results: Apart from snRNA and snoRNA, 560 and 619 microRNAs (miRNAs), including 5 and 2 novel miRNAs, were identified in male and female worms, respectively, without piRNAs being detected in either sex. An analysis of transcriptional profiles showed that, of 564 miRNAs predicted as being differentially transcribed between male and female individuals of T. canis, 218 miRNAs were transcribed exclusively in male and 277 in female worms. Functional enrichment analysis predicted that both male and female miRNAs were mainly involved in regulating embryonic morphogenesis, hemidesmosome assembly and genetic information processing. The miRNAs differentially transcribed between the sexes were predicted to be associated with sex determination, embryonic morphogenesis and nematode larval development. The roles of miRNAs were predicted based on gene ontology (GO) and KEGG pathway annotations. The miRNAs Tc-miR-2305 and Tc-miR-6090 are proposed to have roles in reproduction, embryo development and larval development, and Tc-let-7-5p, Tc-miR-34 and Tc-miR-100 appear to be involved in host-parasite interactions. Together with published information from previous studies, some miRNAs (such as Tc-miR-2861, Tc-miR-2881 and Tc-miR-5126) are predicted to represent drug targets and/or associated with drug resistance.

Conclusions: This is the first exploration of miRNAs in T. canis, which could provide a basis for fundamental investigations of the developmental biology of the parasite, parasite-host interactions and toxocariasis as well as applied areas, such as the diagnosis of infection/disease, drug target discovery and drug resistance detection.
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http://dx.doi.org/10.1186/s13071-016-1508-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4842261PMC
April 2016

Short communication: Experimental toxocarosis in Chinese Kun Ming mice: Dose-dependent larval distribution and modulation of immune responses.

Res Vet Sci 2015 Dec 11;103:16-9. Epub 2015 Sep 11.

Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China. Electronic address:

Toxocarosis is an important parasitic zoonosis which is mainly caused by the infective larvae of Toxocara canis. To identify whether there are correlations among the infectious dose, the larval migrans and immune modulation in inbred Chinese Kun Ming (KM) mice, experimental infections were carried out with a range of dosages of 100, 500, 1000, 2000, and 3000 embryonated eggs (EE). Pathogenic reactions were observed in terms of physical and central nervous symptoms. Distributions of T. canis larvae in liver, lung, kidney, heart and brain organs were respectively detected by scanning tissue sections. Moreover, quantitative real-time PCR was employed to identify the variations of Th2 immune response. The results showed that high inocula resulted in advanced larval emergences and arrested migrations in liver, lung, kidney and brain. However, no larvae were found in any of the histological sections of heart tissues. Higher levels of interleukin (IL)-4, IL-5, and IL-10 were detected along with the increasing inoculation doses, but the heaviest inoculum (3000 EE in this study) resulted in the sharp reduction of these ILs. Although no neurological symptoms or mortalities were noticed, these results indicated dose-dependent distribution patterns and immune regulations of T. canis larvae infection in KM mice.
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http://dx.doi.org/10.1016/j.rvsc.2015.09.002DOI Listing
December 2015
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