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Bouchet C, Umair S, Stasiuk S, Grant W, Green P, Knight J. Target screening using RNA interference in the sheep abomasal nematode parasite Haemonchus contortus. Mol Biochem Parasitol 2024; 260:111648. [PMID: 39004228 DOI: 10.1016/j.molbiopara.2024.111648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 06/25/2024] [Accepted: 07/11/2024] [Indexed: 07/16/2024]
Abstract
RNA interference (RNAi) on parasitic nematodes has been described as a valuable tool for screening putative targets that could be used as novel drug and/or vaccine candidates. This study aimed to set up a pipeline to identify potential targets using RNAi for vaccine/anti-parasite therapy development against Haemonchus contortus, a blood-feeding abomasal nematode parasite. The available H. contortus sequence data was mined for targets, which were tested for essentiality using RNAi electroporation assays. A total of 56 genes were identified and tested for knockdown using electroporation of first-stage larvae (L1) H. contortus with the target double-stranded RNA. Electroporation of L1 proved to be effective overall; 17 targets had a strong phenotype and significant reduction in alive H. contortus, and another 24 had a moderate phenotype with a significant reduction in larvae development. A total of 28 targets showed a significant reduction in the development of H. contortus larvae to the infective stage (L3) following the RNAi assay. Down-regulation of target transcript levels was evaluated in some targets by semi-quantitative PCR. Four out of five genes tested showed complete knockdown of mRNA levels via semi-quantitative PCR, whereas the knockdown was partial for one. In conclusion, the results indicate that the RNAi pathway is confirmed in H. contortus and that several target genes have the potential to be investigated further as possible vaccine candidates.
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Affiliation(s)
| | - Saleh Umair
- AgResearch Ltd, Private Bag 11-008, Palmerston North, New Zealand
| | - Susan Stasiuk
- AgResearch Ltd, Private Bag 11-008, Palmerston North, New Zealand; Department of Parasitology, University of Calgary Alberta, Canada
| | - Warwick Grant
- AgResearch Ltd, Private Bag 11-008, Palmerston North, New Zealand; Department of Physiology Anatomy and Microbiology, School of Life Sciences, La Trobe University, Bundoora 3083, Australia
| | - Peter Green
- AgResearch Ltd, Private Bag 11-008, Palmerston North, New Zealand
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RNAi Silencing of the Biomineralization Gene Perlucin Impairs Oyster Ability to Cope with Ocean Acidification. Int J Mol Sci 2023; 24:ijms24043661. [PMID: 36835072 PMCID: PMC9961701 DOI: 10.3390/ijms24043661] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/01/2023] [Accepted: 02/07/2023] [Indexed: 02/15/2023] Open
Abstract
Calcifying marine organisms, including the eastern oyster (Crassostrea virginica), are vulnerable to ocean acidification (OA) because it is more difficult to precipitate calcium carbonate (CaCO3). Previous investigations of the molecular mechanisms associated with resilience to OA in C. virginica demonstrated significant differences in single nucleotide polymorphism and gene expression profiles among oysters reared under ambient and OA conditions. Converged evidence generated by both of these approaches highlighted the role of genes related to biomineralization, including perlucins. Here, gene silencing via RNA interference (RNAi) was used to evaluate the protective role of a perlucin gene under OA stress. Larvae were exposed to short dicer-substrate small interfering RNA (DsiRNA-perlucin) to silence the target gene or to one of two control treatments (control DsiRNA or seawater) before cultivation under OA (pH ~7.3) or ambient (pH ~8.2) conditions. Two transfection experiments were performed in parallel, one during fertilization and one during early larval development (6 h post-fertilization), before larval viability, size, development, and shell mineralization were monitored. Silenced oysters under acidification stress were the smallest, had shell abnormalities, and had significantly reduced shell mineralization, thereby suggesting that perlucin significantly helps larvae mitigate the effects of OA.
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Genetic manipulations in helminth parasites. J Parasit Dis 2023; 47:203-214. [PMID: 36712591 PMCID: PMC9869838 DOI: 10.1007/s12639-023-01567-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/12/2023] [Indexed: 01/24/2023] Open
Abstract
Screening of vaccine or drug target in parasitic helminth is hindered by lack of robust tool for functional studies of parasite protein which account for the availability of only a few anti-helminthic vaccines, diagnostic assay and slower pace of development of an anthelmintic drug. With the piling up of parasite transcriptomic and genomic data, in silico screening for possible vaccine/drug target could be validated by functional characterization of proteins by RNA interference or CRISPR/Cas9. These reverse genetic engineering tools have opened up a better avenue and opportunity for screening parasitic proteins in vitro as well as in vivo. RNA interference provides a technique for silencing targeted mRNA transcript for understanding a gene function in helminth as evidence by work in Caenorhabditis elegans. Recent genetic engineering tool, CRISPR/Cas9 allows knock-out/deletion of the desired gene in parasitic helminths and the other provision it provides in terms of gene knock-in/insertion in parasite genome is still to be explored in future. This manuscript discussed the work that has been carried out on RNAi and CRISPR/Cas9 for functional studies of helminth parasitic proteins.
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Wickramatunga PGTS, Gunawardene YINS, Wijesinghe KJ, Ellepola ANB, Dassanayake RS. RNAi-mediated silencing of ARV1 in Setaria digitata impairs in-vitro microfilariae release, embryogenesis and adult parasite viability. Vet Parasitol 2020; 284:109189. [PMID: 32739751 DOI: 10.1016/j.vetpar.2020.109189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 02/01/2023]
Abstract
Setaria digitata is a nematode that resides in the peritoneal cavity of ruminants causing cerebrospinal nematodiasis disease affecting livestock and inflicting significant economic forfeitures in Asia. Further, this nematode can infect humans, causing abscesses, allergic reactions, enlarged lymph nodes, eye lesions and inflammation of the lungs. The 'ARE2 required for viability1' (ARV1) encodes for putative lipid transporter localized in the endoplasmic reticulum (ER) and Golgi complex membrane in humans and yeast. In the present study, the functional role of S. digitata ARV1 (SD-ARV1) was investigated using RNA interference (RNAi) reverse genetic tool. The targeted silencing SD-ARV1 transcripts by siRNA mediated RNAi resulted in a dramatic reduction of SD-ARV1 gene and protein expressions in S. digitata, which in turn modulated the parasitic motility, its production of eggs and microfilaria viability. Further, the same silencing caused severe phenotypic deformities such as distortion of eggs and embryonic development arrest in the intrauterine stages of adult female S. digitata. These results suggest that SD-ARV1 plays a pivotal role in worm embryogenesis, adult parasite motility and microfilariae viability. Finally, the ubiquitous presence of ARV1 in human filarial nematodes, its crucial functional roles in nematode biology and its remarkable diversity in primary protein structure compared to homologues in their hosts warrants further investigations to ascertain its candidacy in anthelmintic drug development.
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Affiliation(s)
| | | | - Kaveesha Jayani Wijesinghe
- Department of Chemistry, Faculty of Science, University of Colombo, PO 1490, Kumaratunga Munidasa Mawatha, Colombo, 00300, Sri Lanka
| | - Arjuna N B Ellepola
- Division of Oral Microbiology, Faculty of Dentistry, Health Sciences Center, Kuwait University, Kuwait
| | - Ranil Samantha Dassanayake
- Department of Chemistry, Faculty of Science, University of Colombo, PO 1490, Kumaratunga Munidasa Mawatha, Colombo, 00300, Sri Lanka.
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Abstract
Carbon dioxide (CO2) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO2, suggesting that CO2 plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO2. Here, we review the diverse responses of parasitic and free-living nematodes to CO2. We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO2 detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO2.
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Abstract
Purpose of Review This paper constitutes an update of recent studies on the general biology, molecular genetics, and cellular biology of Strongyloides spp. and related parasitic nematodes. Recent Findings Increasingly, human strongyloidiasis is considered the most neglected of neglected tropical diseases. Despite this, the last 5 years has seen remarkable advances in the molecular biology of Strongyloides spp. Genome sequences for S. stercoralis, S. ratti, S. venezuelensis, S. papillosus, and the related parasite Parastrongyloides trichosuri were created, annotated, and analyzed. These genomic resources, along with a practical transgenesis platform for Strongyloides spp., aided a major achievement, the advent of targeted mutagenesis via CRISPR/Cas9 in S. stercoralis and S. ratti. The genome sequences have also enabled significant molecular epidemiologic and phylogenetic findings on human strongyloidiasis, including the first genetic evidence of zoonotic transmission of S. stercoralis between dogs and humans. Studies of molecular signaling pathways identified the nuclear receptor Ss-DAF-12 as one that can be manipulated in the parasite by exogenous application of its steroid ligands. The chemotherapeutic implications of this were unscored by a study in which a Ss-DAF-12 ligand suppressed autoinfection by S. stercoralis in a new murine model of human strongyloidiasis. Summary Seminal advances in genomics of Strongyloides spp. have transformed research into strongyloidiasis, facilitating fundamental phylogenetic and epidemiologic studies and aiding the deployment of CRISPR/Cas9 gene disruption and editing as functional genomic tools in Strongyloides spp. Studies of Ss-DAF-12 signaling in S. stercoralis demonstrated the potential of this pathway as a novel chemotherapeutic target in parasitic nematodes.
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Affiliation(s)
- Tegegn G. Jaleta
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - James B. Lok
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Marmonier A, Perfus-Barbeoch L, Rancurel C, Boissinot S, Favery B, Demangeat G, Brault V. In Vitro Acquisition of Specific Small Interfering RNAs Inhibits the Expression of Some Target Genes in the Plant Ectoparasite Xiphinema index. Int J Mol Sci 2019; 20:E3266. [PMID: 31277202 PMCID: PMC6651894 DOI: 10.3390/ijms20133266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 12/24/2022] Open
Abstract
Xiphinema index is an important plant parasitic nematode that induces direct damages and specifically transmits the Grapevine fanleaf virus, which is particularly harmful for grapevines. Genomic resources of this nematode species are still limited and no functional gene validation technology is available. RNA interference (RNAi) is a powerful technology to study gene function and here we describe the application of RNAi on several genes in X. index. Soaking the nematodes for 48 h in a suspension containing specific small interfering RNAs resulted in a partial inhibition of the accumulation of some targeted mRNA. However, low reproducible silencing efficiency was observed which could arise from X. index silencing pathway deficiencies. Indeed, essential accustomed proteins for these pathways were not found in the X. index proteome predicted from transcriptomic data. The most reproducible silencing effect was obtained when targeting the piccolo gene potentially involved in endo-exocytosis of synaptic molecules. This represents the first report of gene silencing in a nematode belonging to the Longidoridae family.
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Affiliation(s)
| | | | - Corinne Rancurel
- ISA, INRA, Université Côte d'Azur, CNRS, 06900 Sophia-Antipolis, France
| | | | - Bruno Favery
- ISA, INRA, Université Côte d'Azur, CNRS, 06900 Sophia-Antipolis, France
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Bryant AS, Hallem EA. Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes. Int J Parasitol Drugs Drug Resist 2018; 8:496-510. [PMID: 30396862 PMCID: PMC6287541 DOI: 10.1016/j.ijpddr.2018.10.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 10/22/2018] [Accepted: 10/24/2018] [Indexed: 12/12/2022]
Abstract
Infection with gastrointestinal parasitic nematodes is a major cause of chronic morbidity and economic burden around the world, particularly in low-resource settings. Some parasitic nematode species, including the human-parasitic threadworm Strongyloides stercoralis and human-parasitic hookworms in the genera Ancylostoma and Necator, feature a soil-dwelling infective larval stage that seeks out hosts for infection using a variety of host-emitted sensory cues. Here, we review our current understanding of the behavioral responses of soil-dwelling infective larvae to host-emitted sensory cues, and the molecular and cellular mechanisms that mediate these responses. We also discuss the development of methods for transgenesis and CRISPR/Cas9-mediated targeted mutagenesis in Strongyloides stercoralis and the closely related rat parasite Strongyloides ratti. These methods have established S. stercoralis and S. ratti as genetic model systems for gastrointestinal parasitic nematodes and are enabling more detailed investigations into the neural mechanisms that underlie the sensory-driven behaviors of this medically and economically important class of parasites.
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Affiliation(s)
- Astra S Bryant
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
| | - Elissa A Hallem
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA.
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Tool-Driven Advances in Neuropeptide Research from a Nematode Parasite Perspective. Trends Parasitol 2017; 33:986-1002. [DOI: 10.1016/j.pt.2017.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/10/2017] [Accepted: 08/21/2017] [Indexed: 01/21/2023]
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Misra S, Gupta J, Misra-Bhattacharya S. RNA interference mediated knockdown of Brugia malayi UDP-Galactopyranose mutase severely affects parasite viability, embryogenesis and in vivo development of infective larvae. Parasit Vectors 2017; 10:34. [PMID: 28103957 PMCID: PMC5244609 DOI: 10.1186/s13071-017-1967-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 01/04/2017] [Indexed: 11/10/2022] Open
Abstract
Background Galactofuranose is an essential cell surface component present in bacteria, fungi and several nematodes such as Caenorhabditis spp., Brugia spp., Onchocerca spp. and Strongyloides spp. This sugar maintains the integrity of parasite surface and is essential for virulence. UDP-Galactopyranose mutase (bmugm) plays a key role in Galf biosynthesis by catalyzing conversion of UDP-Galactopyranose into UDP-galactofuranose and knockout studies of the gene in Leishmania major, Mycobacterium and Aspergillus fumigatus displayed attenuated virulence while RNA interference study in C. elegans exhibited detrimental effects. Presence of UGM in several prokaryotic and eukaryotic microbial pathogens and its absence in higher eukaryotes renders it an attractive drug target. In the present study, RNA interference studies have been carried out to validate bmugm as an antifilarial drug target. Methods RNA interference studies using two different sequences of siRNAs targeting bmugm were carried out. The in vitro gene silencing of adult B. malayi parasites was undertaken to observe the effects on parasites. Infective larvae were also exposed to siRNAs and their in vivo development in jirds was observed. Results The in vitro gene silencing induced by siRNA1 and 2 individually as well as together knocked down the bmugm gene expression causing impaired viability of the exposed worms along with extremely reduced motility, abridged microfilarial release and adversely effected embryogenesis. The combinatorial in vitro gene silencing revealed marginally better results than both the siRNAs individually. Thus, infective larvae were treated with siRNA combination which showed downregulation of bmugm mRNA expression resulting into sluggish larval movements and/or death. The siRNA-treated actively motile larvae when inoculated intraperitoneally into jirds demonstrated highly reduced transformation of these larvae into adult worms with detrimental effects on embryogenesis. The effects of gene silencing were long-lasting as the adult worms developed from siRNA-treated larvae showed noticeable knockdown in the target gene expression. Conclusions The validation studies undertaken here conclude that bmugm is essential for the proper development and survival of the parasite and support its candidature as an antifilarial drug target. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-1967-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sweta Misra
- Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, New Delhi, India.,Division of Parasitology CSIR-Central Drug Research Institute, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226031, UP, India
| | - Jyoti Gupta
- Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, New Delhi, India.,Division of Parasitology CSIR-Central Drug Research Institute, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226031, UP, India
| | - Shailja Misra-Bhattacharya
- Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, New Delhi, India. .,Division of Parasitology CSIR-Central Drug Research Institute, BS 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, 226031, UP, India.
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11
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Seybold AC, Wharton DA, Thorne MAS, Marshall CJ. Establishing RNAi in a Non-Model Organism: The Antarctic Nematode Panagrolaimus sp. DAW1. PLoS One 2016; 11:e0166228. [PMID: 27832164 PMCID: PMC5104476 DOI: 10.1371/journal.pone.0166228] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 10/03/2016] [Indexed: 12/02/2022] Open
Abstract
The Antarctic nematode Panagrolaimus sp. DAW1 is one of the only organisms known to survive extensive intracellular freezing throughout its tissues. Although the physiological mechanisms of this extreme adaptation are partly understood, the molecular mechanisms remain largely unknown. RNAi is a method that allows the examination of gene function in a direct, targeted manner, by knocking out specific mRNAs and revealing the effects on the phenotype. In this study we have explored the viability of RNAi in Panagrolaimus sp. DAW1. In the first trial, nematodes were fed E. coli expressing Panagrolaimus sp. DAW1 dsRNA of the embryonic lethal genes rps-2 and dhc, and the blister gene duox. Pd-rps-2(RNAi)-treated nematodes showed a significant decrease in larval hatching. However, qPCR showed no significant decrease in the amount of rps-2 mRNA in Pd-rps-2(RNAi)-treated animals. Several soaking protocols for dsRNA uptake were investigated using the fluorescent dye FITC. Desiccation-enhanced soaking showed the strongest uptake of FITC and resulted in a significant and consistent decrease of mRNA levels of two of the four tested genes (rps-2 and tps-2a), suggesting effective uptake of dsRNA-containing solution by the nematode. These findings suggest that RNAi by desiccation-enhanced soaking is viable in Panagrolaimus sp. DAW1 and provide the first functional genomic approach to investigate freezing tolerance in this non-model organism. RNAi, in conjunction with qPCR, can be used to screen for candidate genes involved in intracellular freezing tolerance in Panagrolaimus sp. DAW1.
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Affiliation(s)
- Anna C. Seybold
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - David A. Wharton
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Michael A. S. Thorne
- British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom
| | - Craig J. Marshall
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- * E-mail:
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Guo X, Zhang H, Zheng X, Zhou Q, Yang Y, Chen X, Du A. Structural and functional characterization of a novel gene, Hc-daf-22, from the strongylid nematode Haemonchus contortus. Parasit Vectors 2016; 9:422. [PMID: 27472920 PMCID: PMC4966567 DOI: 10.1186/s13071-016-1704-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/14/2016] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The strongylid nematode Haemonchus contortus is a parasite of major concern for modern livestock husbandry because hostile environmental conditions may induce diapause in the early fourth-stage larvae. METHODS A new gene Hc-daf-22 was identified which is the homologue of Ce-daf-22 and human SCPx. Genome walking and RACE were performed to obtain the whole cDNA and genomic sequence of this gene. Using qRT-PCR with all developmental stages as templates to explore the transcription level and micro-injection was applied to confirm the promoter activity of the 5'-flanking region. Overexpression, rescue and RNA interference experiments were performed in N2, daf-22 mutant (ok 693) strains of C. elegans to study the gene function of Hc-daf-22. RESULTS The full length gene of Hc-daf-22 (6,939 bp) contained 16 exons separated by 15 introns, and encoded a cDNA of 1,602 bp (533 amino acids, estimated at about 59.3 kDa) with a peak in L3 and L4 in transcriptional level. The Hc-DAF-22 protein was consisted of a 3-oxoacyl-CoA thiolase domain and a SCP2 domain and evolutionarily conserved. The 1,548 bp fragment upstream of the 5'-flanking region was confirmed to have promoter activity compared with 5'-flanking region of Ce-daf-22. The rescue experiment by micro-injection of daf-22 (ok693) mutant strain showed significant increase in body size and brood size in the rescued worms with significantly reduced or completely absent fat granules confirmed by Oil red O staining, indicating that Hc-daf-22 could partially rescue the function of Ce-daf-22. Furthermore, RNAi with Hc-daf-22 could partially silence the endogenous Ce-daf-22 in N2 worms and mimic the phenotype of daf-22 (ok693) mutants. CONCLUSION The gene Hc-daf-22 was isolated and its function identified using C. elegans as a model organism. Our results indicate that Hc-daf-22 shared similar characteristics and function with Ce-daf-22 and may play an important role in peroxisomal β-oxidation and the development in H. contortus.
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Affiliation(s)
- Xiaolu Guo
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058 China
| | - Hongli Zhang
- Zhejiang Center of Animal Disease Control, Hangzhou, 310020 China
| | - Xiuping Zheng
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058 China
| | - Qianjin Zhou
- Faculty of Life Science and Biotechnology, Ningbo University, Ningbo, 315211 China
| | - Yi Yang
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058 China
| | - Xueqiu Chen
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058 China
| | - Aifang Du
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou, 310058 China
- Present address: Institute of Preventive Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058 China
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13
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Britton C, Roberts B, Marks ND. Functional Genomics Tools for Haemonchus contortus and Lessons From Other Helminths. ADVANCES IN PARASITOLOGY 2016; 93:599-623. [PMID: 27238014 DOI: 10.1016/bs.apar.2016.02.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The availability of genome and transcriptome data for parasitic nematodes, including Haemonchus contortus, has highlighted the need to develop functional genomics tools. Comparative genomic analysis, particularly using data from the free-living nematode Caenorhabditis elegans, can help predict gene function. Reliable approaches to study function directly in parasitic nematodes are currently lacking. However, gene knockdown by RNA interference (RNAi) is being successfully used in schistosome and planarian species to define gene functions. Lessons from these systems may be applied to improve RNAi in H. contortus. Previous studies in H. contortus and related nematodes demonstrated reliable RNAi-mediated silencing of some genes, but not others. Current data suggest that susceptibility to RNAi in these nematodes is limited to genes expressed in sites accessible to the environment, such as the gut, amphids and excretory cell. Therefore, RNAi is functional in H. contortus, but improvements are needed to develop this system as a functional genomics platform. Here, we summarize RNAi studies on H. contortus and discuss the optimization of RNA delivery and improvements to culture methods to enhance larval development, protein turnover and the induction of phenotypic effects in vitro. The transgenic delivery of RNA or dominant-negative gene constructs and the recently developed CRISPR/Cas genome-editing technique are considered as potential alternative approaches for gene knockout. This is a key time to devote greater effort in progressing from genome to function, to improve our understanding of the biology of Haemonchus and identify novel targets for parasite control.
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Affiliation(s)
- C Britton
- University of Glasgow, Glasgow, United Kingdom
| | - B Roberts
- University of Glasgow, Glasgow, United Kingdom
| | - N D Marks
- University of Glasgow, Glasgow, United Kingdom
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14
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Ratnappan R, Vadnal J, Keaney M, Eleftherianos I, O'Halloran D, Hawdon JM. RNAi-mediated gene knockdown by microinjection in the model entomopathogenic nematode Heterorhabditis bacteriophora. Parasit Vectors 2016; 9:160. [PMID: 26993791 PMCID: PMC4797128 DOI: 10.1186/s13071-016-1442-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/10/2016] [Indexed: 12/21/2022] Open
Abstract
Background Parasitic nematodes threaten the health of humans and livestock and cause a major financial and socioeconomic burden to modern society. Given the widespread distribution of diseases caused by parasitic nematodes there is an urgent need to develop tools that will elucidate the genetic complexity of host-parasite interactions. Heterorhabditis bacteriophora is a parasitic nematode that allows simultaneous monitoring of nematode infection processes and host immune function, and offers potential as a tractable model for parasitic nematode infections. However, molecular tools to investigate these processes are required prior to its widespread acceptance as a robust model organism. In this paper we describe microinjection in adult H. bacteriophora as a suitable means of dsRNA delivery to knockdown gene transcripts. Methods RNA interference was used to knockdown four genes by injecting dsRNA directly into the gonad of adult hermaphrodite nematodes. RNAi phenotypes were scored in the F1 progeny on the fifth day post-injection, and knockdown of gene-specific transcripts was quantified with real-time quantitative RT-PCR (qRT-PCR). Results RNAi injection in adult hermaphrodites significantly decreased the level of target transcripts to varying degrees when compared with controls. The genes targeted by RNAi via injection included cct-2, nol-5, dpy-7, and dpy-13. In each case, RNAi knockdown was confirmed phenotypically by examining the progeny of injected animals, and also confirmed at the transcriptional level by real-time qRT-PCR. Conclusions Here we describe for the first time the successful use of microinjection to knockdown gene transcripts in H. bacteriophora. This technique can be used widely to study the molecular basis of parasitism.
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Affiliation(s)
- Ramesh Ratnappan
- Department of Microbiology Immunology and Tropical Medicine, George Washington University Medical Center, Washington, DC, 20037, USA
| | - Jonathan Vadnal
- Department of Microbiology Immunology and Tropical Medicine, George Washington University Medical Center, Washington, DC, 20037, USA
| | - Melissa Keaney
- Department of Microbiology Immunology and Tropical Medicine, George Washington University Medical Center, Washington, DC, 20037, USA
| | - Ioannis Eleftherianos
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, suite 6000, 800 22nd Street NW, Washington, DC, 20052, USA
| | - Damien O'Halloran
- Department of Biological Sciences, George Washington University, Science and Engineering Hall, suite 6000, 800 22nd Street NW, Washington, DC, 20052, USA.,Institute for Neuroscience, George Washington University, 636 Ross Hall, 2300 I Street NW, Washington, DC, 20052, USA
| | - John M Hawdon
- Department of Microbiology Immunology and Tropical Medicine, George Washington University Medical Center, Washington, DC, 20037, USA.
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15
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Ondrovics M, Gasser RB, Joachim A. Recent Advances in Elucidating Nematode Moulting - Prospects of Using Oesophagostomum dentatum as a Model. ADVANCES IN PARASITOLOGY 2015; 91:233-64. [PMID: 27015950 DOI: 10.1016/bs.apar.2015.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There are major gaps in our knowledge of many molecular biological processes that take place during the development of parasitic nematodes, in spite of the fact that understanding such processes could lead to new ways of treating and controlling parasitic diseases via the disruption of one or more biological pathways in the parasites. Progress in genomics, transcriptomics, proteomics and bioinformatics now provides unique opportunities to investigate the molecular basis of key developmental processes in parasitic nematodes. The porcine nodule worm, Oesophagostomum dentatum, represents a large order (Strongylida) of socioeconomically important nematodes, and provides a useful platform for exploring molecular developmental processes, particularly given that this nematode can be grown and maintained in culture in vitro for periods longer than most other nematodes of this order. In this article, we focus on the moulting process (ecdysis) in nematodes; review recent advances in our understanding of molecular aspects of moulting in O. dentatum achieved by using integrated proteomic-bioinformatic tools and discuss key implications and future prospects for research in this area, also with respect to developing new anti-nematode interventions and biotechnological outcomes.
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Affiliation(s)
- Martina Ondrovics
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
| | - Anja Joachim
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
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16
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Ma GX, Zhou RQ, Song ZH, Zhu HH, Zhou ZY, Zeng YQ. Molecular mechanism of serine/threonine protein phosphatase 1 (PP1cα-PP1r7) in spermatogenesis of Toxocara canis. Acta Trop 2015; 149:148-54. [PMID: 26026715 DOI: 10.1016/j.actatropica.2015.05.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/20/2015] [Accepted: 05/25/2015] [Indexed: 01/21/2023]
Abstract
Toxocariasis is one of the most important, but neglected, zoonoses, which is mainly caused by Toxocara canis. To better understand the role of serine/threonine protein phosphatase 1 (PP1) in reproductive processes of male adult T. canis, differential expression analysis was used to reveal the profiles of PP1 catalytic subunit α (PP1cα) gene Tc-stp-1 and PP1 regulatory subunit 7 (PP1r7) gene TcM-1309. Indirect fluorescence immunocytochemistry was carried out to determine the subcellular distribution of PP1cα. Double-stranded RNA interference (RNAi) assays were employed to illustrate the function and mechanism of PP1cα in male adult reproduction. Real-time quantitative PCR (qPCR) showed transcriptional consistency of Tc-stp-1 and TcM-1309 in sperm-producing germline tissues and localization research showed cytoplasmic distribution of PP1cα in sf9 cells, which indicated relevant involvements of PP1cα and PP1r7 in spermatogenesis. Moreover, spatiotemporal transcriptional differences of Tc-stp-1 were determined by gene knockdown analysis, which revealed abnormal morphologies and blocked meiotic divisions of spermatocytes by phenotypic aberration scanning, thereby highlighting the crucial involvement of PP1cα in spermatogenesis. These results revealed a PP1cα-PP1r7 mechanism by which PP1 regulates kinetochore-microtubule interactions in spermatogenesis and provided important clues to identify novel drug or vaccine targets for toxocariasis control.
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Affiliation(s)
- Guang Xu Ma
- Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China
| | - Rong Qiong Zhou
- Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China.
| | - Zhen Hui Song
- Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China
| | - Hong Hong Zhu
- Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China
| | - Zuo Yong Zhou
- Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, People's Republic of China
| | - Yuan Qin Zeng
- College of Life Sciences, Southwest University, Chongqing 402460, People's Republic of China
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Cantacessi C, Hofmann A, Campbell BE, Gasser RB. Impact of next-generation technologies on exploring socioeconomically important parasites and developing new interventions. Methods Mol Biol 2015; 1247:437-474. [PMID: 25399114 DOI: 10.1007/978-1-4939-2004-4_31] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
High-throughput molecular and computer technologies have become instrumental for systems biological explorations of pathogens, including parasites. For instance, investigations of the transcriptomes of different developmental stages of parasitic nematodes give insights into gene expression, regulation and function in a parasite, which is a significant step to understanding their biology, as well as interactions with their host(s) and disease. This chapter (1) gives a background on some key parasitic nematodes of socioeconomic importance, (2) describes sequencing and bioinformatic technologies for large-scale studies of the transcriptomes and genomes of these parasites, (3) provides some recent examples of applications and (4) emphasizes the prospects of fundamental biological explorations of parasites using these technologies for the development of new interventions to combat parasitic diseases.
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Affiliation(s)
- Cinzia Cantacessi
- Department of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, 3010, Australia
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18
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Marker genes for activation of the RNA interference (RNAi) pathway in the free-living nematode Caenorhabditis elegans and RNAi development in the ovine nematode Teladorsagia circumcincta. J Helminthol 2013; 89:208-16. [PMID: 24345514 DOI: 10.1017/s0022149x13000801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The nematode Teladorsagia circumcincta is a major cause of parasitic gastroenteritis in sheep in temperate regions. The development of resistance to the major anthelmintic classes used for its control is a threat to small ruminant farming sustainability. Vaccination is a potential alternative control method for this nematode. Gene datasets can be exploited to identify potential vaccine candidates and these validated further by methods such as RNA interference (RNAi) prior to vaccine trials. Previous reports indicate that RNAi in parasitic nematodes is inconsistent and, to date, there are no internal controls that indicate activation of the RNAi pathway in response to double-stranded RNA (dsRNA). The present aims were to determine whether or not the transcription levels of potential marker genes in the RNAi pathway could indicate activation of the pathway in Caenorhabditis elegans and to develop an RNAi platform in T. circumcincta. In C. elegans, transcript levels of three candidate marker genes, Ce-dcr-1 (Dicer), Ce-ego-1 (Enhancer of Glp-One family member) and Ce-rsd-3 (RNAi Spreading Defective), were analysed and results indicated that activation of the pathway had no effect on transcript levels of these genes. In T. circumcincta, two vaccine candidate genes from the Activation-associated Secreted Protein (ASP) family were targets for knockdown. RNAi experiments showed successful silencing of both targets, although inconsistencies in efficacy were observed. After testing a number of parameters that might affect variability, it was found that the length of the storage period of the larvae plays an important role in the consistency of the RNAi results.
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Singh PK, Kushwaha S, Mohd S, Pathak M, Misra-Bhattacharya S. In vitro gene silencing of independent phosphoglycerate mutase (iPGM) in the filarial parasite Brugia malayi. Infect Dis Poverty 2013; 2:5. [PMID: 23849829 PMCID: PMC3707094 DOI: 10.1186/2049-9957-2-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 03/21/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The phosphoglycerate mutase (PGM) enzyme catalyzes the interconversion of 2- and 3-phosphoglycerate in the glycolytic /gluconeogenic pathways that are present in the majority of cellular organisms. They can be classified as cofactor-dependent PGM (dPGM) or cofactor-independent PGM (iPGM). Vertebrates, yeasts, and many bacteria have only dPGM, while higher plants, nematodes, archaea, and many other bacteria have only iPGM. A small number of bacteria, including Escherichia coli and certain archaea and protozoa, contain both forms. The silencing of ipgm in Caenorhabditis elegans (C. elegans) has demonstrated the importance of this enzyme in parasite viability and, therefore, its potential as an anthelmintic drug target. In this study, the role of the Brugia malayi (B. malayi) ipgm in parasite viability, microfilaria release, embryogenesis, and in vivo development of infective larvae post-gene silencing was explored by applying ribonucleic acid (RNA) interference studies. RESULTS The in vitro ipgm gene silencing by small interfering RNA (siRNA) leads to severe phenotypic deformities in the intrauterine developmental stages of female worms with a drastic reduction (~90%) in the motility of adult parasites and a significantly reduced (80%) release of microfilariae (mf) by female worms in vitro. Almost half of the in vitro-treated infective L3 displayed sluggish movement. The in vivo survival and development of siRNA-treated infective larvae (L3) was investigated in the peritoneal cavity of jirds where a ~45% reduction in adult worm establishment was observed. CONCLUSION The findings clearly suggest that iPGM is essential for both larval and adult stages of B. malayi parasite and that it plays a pivotal role in female worm embryogenesis. The results thus validate the Bm-iPGM as a putative anti-filarial drug target.
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Affiliation(s)
- Prashant Kumar Singh
- Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, UP, 226021, India
| | - Susheela Kushwaha
- Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, UP, 226021, India
| | - Shahab Mohd
- Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, UP, 226021, India
| | - Manisha Pathak
- Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, UP, 226021, India
| | - Shailja Misra-Bhattacharya
- Division of Parasitology, CSIR-Central Drug Research Institute, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, UP, 226021, India
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20
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Britton C, Samarasinghe B, Knox DP. Ups and downs of RNA interference in parasitic nematodes. Exp Parasitol 2012; 132:56-61. [DOI: 10.1016/j.exppara.2011.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/27/2011] [Accepted: 08/03/2011] [Indexed: 01/06/2023]
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21
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Developments in RNA interference and genetic transformation to define gene function in parasitic helminths. Parasitology 2012; 139:557-9. [PMID: 22459432 DOI: 10.1017/s0031182012000108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Hagen J, Lee EF, Fairlie WD, Kalinna BH. Functional genomics approaches in parasitic helminths. Parasite Immunol 2012; 34:163-82. [PMID: 21711361 DOI: 10.1111/j.1365-3024.2011.01306.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As research on parasitic helminths is moving into the post-genomic era, an enormous effort is directed towards deciphering gene function and to achieve gene annotation. The sequences that are available in public databases undoubtedly hold information that can be utilized for new interventions and control but the exploitation of these resources has until recently remained difficult. Only now, with the emergence of methods to genetically manipulate and transform parasitic worms will it be possible to gain a comprehensive understanding of the molecular mechanisms involved in nutrition, metabolism, developmental switches/maturation and interaction with the host immune system. This review focuses on functional genomics approaches in parasitic helminths that are currently used, to highlight potential applications of these technologies in the areas of cell biology, systems biology and immunobiology of parasitic helminths.
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Affiliation(s)
- J Hagen
- Department of Veterinary Science, Centre for Animal Biotechnology, The University of Melbourne, Vic., Australia
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23
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Cantacessi C, Campbell BE, Gasser RB. Key strongylid nematodes of animals — Impact of next-generation transcriptomics on systems biology and biotechnology. Biotechnol Adv 2012; 30:469-88. [DOI: 10.1016/j.biotechadv.2011.08.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 08/09/2011] [Accepted: 08/19/2011] [Indexed: 10/17/2022]
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24
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RINALDI M, GELDHOF P. Immunologically based control strategies for ostertagiosis in cattle: where do we stand? Parasite Immunol 2012; 34:254-64. [DOI: 10.1111/j.1365-3024.2011.01313.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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25
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CANTACESSI C, CAMPBELL BE, JEX AR, YOUNG ND, HALL RS, RANGANATHAN S, GASSER RB. Bioinformatics meets parasitology. Parasite Immunol 2012; 34:265-75. [DOI: 10.1111/j.1365-3024.2011.01304.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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26
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Selkirk ME, Huang SC, Knox DP, Britton C. The development of RNA interference (RNAi) in gastrointestinal nematodes. Parasitology 2012; 139:605-12. [PMID: 22459433 DOI: 10.1017/s0031182011002332] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Despite the utility of RNAi for defining gene function in Caenorhabditis elegans and early successes reported in parasitic nematodes, RNAi has proven to be stubbornly inconsistent or ineffective in the animal parasitic nematodes examined to date. Here, we summarise some of our experiences with RNAi in parasitic nematodes affecting animals and discuss the available data in the context of our own unpublished work, taking account of mode of delivery, larval activation, site of gene transcription and the presence/absence of essential RNAi pathway genes as defined by comparisons to C. elegans. We discuss future directions briefly including the evaluation of nanoparticles as a means to enhance delivery of interfering RNA to the target worm tissue.
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Affiliation(s)
- Murray E Selkirk
- Division of Cell and Molecular Biology, Department of Life Sciences, Imperial College London, London SW7 2AZ
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27
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Abstract
SUMMARYIn this study we assessed three technologies for silencing gene expression by RNA interference (RNAi) in the sheep parasitic nematode Haemonchus contortus. We chose as targets five genes that are essential in Caenorhabditis elegans (mitr-1, pat-12, vha-19, glf-1 and noah-1), orthologues of which are present and expressed in H. contortus, plus four genes previously tested by RNAi in H. contortus (ubiquitin, tubulin, paramyosin, tropomyosin). To introduce double-stranded RNA (dsRNA) into the nematodes we tested (1) feeding free-living stages of H. contortus with Escherichia coli that express dsRNA targetting the test genes; (2) electroporation of dsRNA into H. contortus eggs or larvae; and (3) soaking adult H. contortus in dsRNA. For each gene tested we observed reduced levels of mRNA in the treated nematodes, except for some electroporation conditions. We did not observe any phenotypic changes in the worms in the electroporation or dsRNA soaking experiments. The feeding method, however, elicited observable changes in the development and viability of larvae for five of the eight genes tested, including the ‘essential’ genes, Hc-pat-12, Hc-vha-19 and Hc-glf-1. We recommend the E. coli feeding method for RNAi in H. contortus and provide recommendations for future research directions for RNAi in this species.
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28
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Landmann F, Foster JM, Slatko BE, Sullivan W. Efficient in vitro RNA interference and immunofluorescence-based phenotype analysis in a human parasitic nematode, Brugia malayi. Parasit Vectors 2012; 5:16. [PMID: 22243803 PMCID: PMC3292814 DOI: 10.1186/1756-3305-5-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 01/13/2012] [Indexed: 11/26/2022] Open
Abstract
Background RNA interference (RNAi) is an efficient reverse genetics technique for investigating gene function in eukaryotes. The method has been widely used in model organisms, such as the free-living nematode Caenorhabditis elegans, where it has been deployed in genome-wide high throughput screens to identify genes involved in many cellular and developmental processes. However, RNAi techniques have not translated efficiently to animal parasitic nematodes that afflict humans, livestock and companion animals across the globe, creating a dependency on data tentatively inferred from C. elegans. Results We report improved and effective in vitro RNAi procedures we have developed using heterogeneous short interfering RNA (hsiRNA) mixtures that when coupled with optimized immunostaining techniques yield detailed analysis of cytological defects in the human parasitic nematode, Brugia malayi. The cellular disorganization observed in B. malayi embryos following RNAi targeting the genes encoding γ-tubulin, and the polarity determinant protein, PAR-1, faithfully phenocopy the known defects associated with gene silencing of their C. elegans orthologs. Targeting the B. malayi cell junction protein, AJM-1 gave a similar but more severe phenotype than that observed in C. elegans. Cellular phenotypes induced by our in vitro RNAi procedure can be observed by immunofluorescence in as little as one week. Conclusions We observed cytological defects following RNAi targeting all seven B. malayi transcripts tested and the phenotypes mirror those documented for orthologous genes in the model organism C. elegans. This highlights the reliability, effectiveness and specificity of our RNAi and immunostaining procedures. We anticipate that these techniques will be widely applicable to other important animal parasitic nematodes, which have hitherto been mostly refractory to such genetic analysis.
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Affiliation(s)
- Frédéric Landmann
- Department of Molecular, Cell and Developmental Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95604, USA.
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29
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Abstract
SUMMARYAlmost a decade has passed since the first report of RNA interference (RNAi) in a parasitic helminth. Whilst much progress has been made with RNAi informing gene function studies in disparate nematode and flatworm parasites, substantial and seemingly prohibitive difficulties have been encountered in some species, hindering progress. An appraisal of current practices, trends and ideals of RNAi experimental design in parasitic helminths is both timely and necessary for a number of reasons: firstly, the increasing availability of parasitic helminth genome/transcriptome resources means there is a growing need for gene function tools such as RNAi; secondly, fundamental differences and unique challenges exist for parasite species which do not apply to model organisms; thirdly, the inherent variation in experimental design, and reported difficulties with reproducibility undermine confidence. Ideally, RNAi studies of gene function should adopt standardised experimental design to aid reproducibility, interpretation and comparative analyses. Although the huge variations in parasite biology and experimental endpoints make RNAi experimental design standardization difficult or impractical, we must strive to validate RNAi experimentation in helminth parasites. To aid this process we identify multiple approaches to RNAi experimental validation and highlight those which we deem to be critical for gene function studies in helminth parasites.
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30
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Abstract
Parasitic diseases cause important losses in public and veterinary health worldwide. Novel drugs, more reliable diagnostic techniques and vaccine candidates are urgently needed. Due to the complexity of parasites and the intricate relationship with their hosts, development of successful tools to fight parasites has been very limited to date. The growing information on individual parasite genomes is now allowing the use of a broader range of potential strategies to gain deeper insights into the host-parasite relationship and has increased the possibilities to develop molecular-based tools in the field of parasitology. Nevertheless, functional studies of respective genes are still scarce. The RNA interference phenomenon resulting in the regulation of protein expression through the specific degradation of defined mRNAs, and more specifically the possibility of artificially induce it, has shown to be a powerful tool for the investigation of proteins function in many organisms. Recent advances in the design and delivery of targeting molecules allow efficient and highly specific gene silencing in different types of parasites, pointing out this technology as a powerful tool for the identification of novel vaccine candidates or drug targets at the high-throughput level in the near future, and could enable researchers to functionally annotate parasite genomes. The aim of this review is to provide a comprehensive overview on the current advances and pitfalls in gene silencing mechanisms, techniques, applications and prospects in animal parasites.
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31
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Abstract
RNA interference (RNAi) is a powerful research tool that has enabled molecular insights into gene activity, pathway analysis, partial loss-of-function phenotypes, and large-scale genomic discovery of gene function. While RNAi works extremely well in the non-parasitic nematode C. elegans, it is also especially useful in organisms that lack facile genetic analysis. Extensive genetic analysis of the mechanisms, delivery and regulation of RNAi in C. elegans has provided mechanistic and phenomenological insights into why RNAi is so effective in this species. These insights are useful for the testing and development of RNAi in other nematodes, including parasitic nematodes where more effective RNAi would be extremely useful. Here, we review the current advances in C. elegans for RNA delivery methods, regulation of cell autonomous and systemic RNAi phenomena, and implications of enhanced RNAi mutants. These discussions, with a focus on mechanism and cross-species application, provide new perspectives for optimizing RNAi in other species.
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32
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Maule AG, McVeigh P, Dalzell JJ, Atkinson L, Mousley A, Marks NJ. An eye on RNAi in nematode parasites. Trends Parasitol 2011; 27:505-13. [PMID: 21885343 DOI: 10.1016/j.pt.2011.07.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 07/27/2011] [Accepted: 07/29/2011] [Indexed: 11/19/2022]
Abstract
RNA interference (RNAi) has revolutionised approaches to gene function determination. From a parasitology perspective, gene function studies have the added dimension of providing validation data, increasingly deemed essential to the initial phases of drug target selection, pre-screen development. Notionally advantageous to those working on nematode parasites is the fact that Caenorhabditis elegans research spawned RNAi discovery and continues to seed our understanding of its fundamentals. Unfortunately, RNAi data for nematode parasites illustrate variable and inconsistent susceptibilities which undermine confidence and exploitation. Now well-ensconced in an era of nematode parasite genomics, we can begin to unscramble this variation.
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Affiliation(s)
- Aaron G Maule
- Molecular Bioscience-Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen's University Belfast, Belfast BT9 7BL, UK.
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33
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Dalzell JJ, McVeigh P, Warnock ND, Mitreva M, Bird DM, Abad P, Fleming CC, Day TA, Mousley A, Marks NJ, Maule AG. RNAi effector diversity in nematodes. PLoS Negl Trop Dis 2011; 5:e1176. [PMID: 21666793 PMCID: PMC3110158 DOI: 10.1371/journal.pntd.0001176] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 04/04/2011] [Indexed: 11/22/2022] Open
Abstract
While RNA interference (RNAi) has been deployed to facilitate gene function studies in diverse helminths, parasitic nematodes appear variably susceptible. To test if this is due to inter-species differences in RNAi effector complements, we performed a primary sequence similarity survey for orthologs of 77 Caenorhabditis elegans RNAi pathway proteins in 13 nematode species for which genomic or transcriptomic datasets were available, with all outputs subjected to domain-structure verification. Our dataset spanned transcriptomes of Ancylostoma caninum and Oesophagostomum dentatum, and genomes of Trichinella spiralis, Ascaris suum, Brugia malayi, Haemonchus contortus, Meloidogyne hapla, Meloidogyne incognita and Pristionchus pacificus, as well as the Caenorhabditis species C. brenneri, C. briggsae, C. japonica and C. remanei, and revealed that: (i) Most of the C. elegans proteins responsible for uptake and spread of exogenously applied double stranded (ds)RNA are absent from parasitic species, including RNAi-competent plant-nematodes; (ii) The Argonautes (AGOs) responsible for gene expression regulation in C. elegans are broadly conserved, unlike those recruited during the induction of RNAi by exogenous dsRNA; (iii) Secondary Argonautes (SAGOs) are poorly conserved, and the nuclear AGO NRDE-3 was not identified in any parasite; (iv) All five Caenorhabditis spp. possess an expanded RNAi effector repertoire relative to the parasitic nematodes, consistent with the propensity for gene loss in nematode parasites; (v) In spite of the quantitative differences in RNAi effector complements across nematode species, all displayed qualitatively similar coverage of functional protein groups. In summary, we could not identify RNAi effector deficiencies that associate with reduced susceptibility in parasitic nematodes. Indeed, similarities in the RNAi effector complements of RNAi refractory and competent nematode parasites support the broad applicability of this research genetic tool in nematodes. Many organisms regulate gene expression through an RNA interference (RNAi) pathway, first characterized in the nematode Caenorhabditis elegans. This pathway can be triggered experimentally using double-stranded (ds)RNA to selected gene targets, thereby allowing researchers to ‘silence’ individual genes and so investigate their function. It is hoped that this technology will facilitate gene silencing in important parasitic nematodes that impose a considerable health and economic burden on mankind. Unfortunately, differences in RNAi susceptibility have been observed between species. Here we investigated the possibility that differences in the complement of effector proteins involved in the RNAi pathway are responsible for these differences in susceptibility. Our data revealed that most facets of the RNAi pathway are well represented across parasitic nematodes, although there were fewer pathway proteins in other nematodes compared to C. elegans. In contrast, the proteins responsible for uptake and spread of dsRNA are not well represented in parasitic nematodes. However, the importance of these differences is undermined by our observation that the protein complements in all the parasites were qualitatively similar, regardless of RNAi-susceptibility. Clearly, differences in the RNAi pathway of parasitic nematodes do not explain the variations in susceptibility to experimental RNAi.
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Affiliation(s)
- Johnathan J. Dalzell
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Paul McVeigh
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
- * E-mail:
| | - Neil D. Warnock
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Makedonka Mitreva
- The Genome Center, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David McK. Bird
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Pierre Abad
- INRA, Unité Interactions Plantes-Microorganismes et Santé Végétale, Antibes, France
| | | | - Tim A. Day
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, United States of America
| | - Angela Mousley
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Nikki J. Marks
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Aaron G. Maule
- Molecular Biosciences-Parasitology, School of Biological Sciences, Queen's University Belfast, Belfast, United Kingdom
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SLO-1-channels of parasitic nematodes reconstitute locomotor behaviour and emodepside sensitivity in Caenorhabditis elegans slo-1 loss of function mutants. PLoS Pathog 2011; 7:e1001330. [PMID: 21490955 PMCID: PMC3072372 DOI: 10.1371/journal.ppat.1001330] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 03/04/2011] [Indexed: 11/24/2022] Open
Abstract
The calcium-gated potassium channel SLO-1 in Caenorhabditis elegans was recently identified as key component for action of emodepside, a new anthelmintic drug with broad spectrum activity. In this study we identified orthologues of slo-1 in Ancylostoma caninum, Cooperia oncophora, and Haemonchus contortus, all important parasitic nematodes in veterinary medicine. Furthermore, functional analyses of these slo-1 orthologues were performed using heterologous expression in C. elegans. We expressed A. caninum and C. oncophora slo-1 in the emodepside-resistant genetic background of the slo-1 loss-of-function mutant NM1968 slo-1(js379). Transformants expressing A. caninum slo-1 from C. elegans slo-1 promoter were highly susceptible (compared to the fully emodepside-resistant slo-1(js379)) and showed no significant difference in their emodepside susceptibility compared to wild-type C. elegans (p = 0.831). Therefore, the SLO-1 channels of A. caninum and C. elegans appear to be completely functionally interchangeable in terms of emodepside sensitivity. Furthermore, we tested the ability of the 5′ flanking regions of A. caninum and C. oncophora slo-1 to drive expression of SLO-1 in C. elegans and confirmed functionality of the putative promoters in this heterologous system. For all transgenic lines tested, expression of either native C. elegans slo-1 or the parasite-derived orthologue rescued emodepside sensitivity in slo-1(js379) and the locomotor phenotype of increased reversal frequency confirming the reconstitution of SLO-1 function in the locomotor circuits. A potent mammalian SLO-1 channel inhibitor, penitrem A, showed emodepside antagonising effects in A. caninum and C. elegans. The study combined the investigation of new anthelmintic targets from parasitic nematodes and experimental use of the respective target genes in C. elegans, therefore closing the gap between research approaches using model nematodes and those using target organisms. Considering the still scarcely advanced techniques for genetic engineering of parasitic nematodes, the presented method provides an excellent opportunity for examining the pharmacofunction of anthelmintic targets derived from parasitic nematodes. In parasitic nematodes, experiments at the molecular level are currently not feasible, since in vitro culture and genetic engineering are still in their infancy. In the present study we chose the model organism Caenorhabditis elegans not only as a mere expression system for genes from parasitic nematodes, but used the transformants to examine the functionality of the expressed proteins for mediating anthelmintic effects in vivo. The results of our experiments confirmed that SLO-1 channels mediate the activity of the new anthelmintic drug emodepside and showed that the mode of action is conserved through several nematode species. The chosen method allowed us to examine the functionality of proteins from parasitic nematodes in a defined genetic background. Notably, expression of the parasitic nematode gene in anthelmintic-resistant C. elegans completely restored drug susceptibility. As C. elegans is highly tractable to molecular genetic and pharmacological approaches, the generation of lines expressing the parasite drug target will greatly facilitate structure-function analysis of the interaction between emodepside and ion channels with direct relevance to its anthelmintic properties. In a broader context, the demonstration of C. elegans as a heterologous expression system for functional analysis of parasite proteins further strengthens this as a model for anthelmintic studies.
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Chatterji BP, Jindal B, Srivastava S, Panda D. Microtubules as antifungal and antiparasitic drug targets. Expert Opin Ther Pat 2011; 21:167-86. [PMID: 21204724 DOI: 10.1517/13543776.2011.545349] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Diseases caused by fungi and parasites are major illnesses in humans as well as in animals. Microtubule-targeted drugs are highly effective for the treatment of fungal and parasitic infections; however, several human parasitic infections such as malaria, trypanosomiasis and leishmaniasis do not have effective remedial drugs. In addition, the emergence of drug-resistant fungi and parasites makes the discovery of new drugs imperative. AREAS COVERED This article describes similarities and dissimilarities between parasitic, fungal and mammalian tubulins and focuses on microtubule-targeting agents and therapeutic approaches for the treatment of fungal and parasitic diseases. New microtubule-targeted antileishmanial, antimalarial and antifungal drugs, with structures, biological activities and related patents, are described. The potential of dsRNA against tubulin to inhibit proliferation of protozoan and helminthic parasites is also discussed. Patent documents up to 2010 have been searched on USPTO, Patentscope, and Espacenet resources. EXPERT OPINION The article suggests that vaccination with tubulin may offer novel opportunities for the antiparasitic treatment. Native or recombinant tubulin used as antigen has been shown to elicit immune response and cure infection partially or fully in animals upon challenge by protozoan parasites and helminths, thus indicating the suitability of tubulin as a vaccine against parasitic diseases.
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Affiliation(s)
- Biswa Prasun Chatterji
- Indian Institute of Technology Bombay, Department of Biosciences and Bioengineering, Powai, Mumbai-400076, India
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Song C, Gallup JM, Day TA, Bartholomay LC, Kimber MJ. Development of an in vivo RNAi protocol to investigate gene function in the filarial nematode, Brugia malayi. PLoS Pathog 2010; 6:e1001239. [PMID: 21203489 PMCID: PMC3009605 DOI: 10.1371/journal.ppat.1001239] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 11/23/2010] [Indexed: 01/25/2023] Open
Abstract
Our ability to control diseases caused by parasitic nematodes is constrained by a limited portfolio of effective drugs and a paucity of robust tools to investigate parasitic nematode biology. RNA interference (RNAi) is a reverse-genetics tool with great potential to identify novel drug targets and interrogate parasite gene function, but present RNAi protocols for parasitic nematodes, which remove the parasite from the host and execute RNAi in vitro, are unreliable and inconsistent. We have established an alternative in vivo RNAi protocol targeting the filarial nematode Brugia malayi as it develops in an intermediate host, the mosquito Aedes aegypti. Injection of worm-derived short interfering RNA (siRNA) and double stranded RNA (dsRNA) into parasitized mosquitoes elicits suppression of B. malayi target gene transcript abundance in a concentration-dependent fashion. The suppression of this gene, a cathepsin L-like cysteine protease (Bm-cpl-1) is specific and profound, both injection of siRNA and dsRNA reduce transcript abundance by 83%. In vivo Bm-cpl-1 suppression results in multiple aberrant phenotypes; worm motility is inhibited by up to 69% and parasites exhibit slow-moving, kinked and partial-paralysis postures. Bm-cpl-1 suppression also retards worm growth by 48%. Bm-cpl-1 suppression ultimately prevents parasite development within the mosquito and effectively abolishes transmission potential because parasites do not migrate to the head and proboscis. Finally, Bm-cpl-1 suppression decreases parasite burden and increases mosquito survival. This is the first demonstration of in vivo RNAi in animal parasitic nematodes and results indicate this protocol is more effective than existing in vitro RNAi methods. The potential of this new protocol to investigate parasitic nematode biology and to identify and validate novel anthelmintic drug targets is discussed.
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Affiliation(s)
- Chuanzhe Song
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Jack M. Gallup
- Department of Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Tim A. Day
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Lyric C. Bartholomay
- Department of Entomology, College of Agriculture and Life Sciences, Iowa State University, Ames, Iowa, United States of America
| | - Michael J. Kimber
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
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Xu MJ, Chen N, Song HQ, Lin RQ, Huang CQ, Yuan ZG, Zhu XQ. RNAi-mediated silencing of a novel Ascaris suum gene expression in infective larvae. Parasitol Res 2010; 107:1499-503. [DOI: 10.1007/s00436-010-2027-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 08/05/2010] [Indexed: 11/27/2022]
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Chen N, Xu MJ, Nisbet AJ, Huang CQ, Lin RQ, Yuan ZG, Song HQ, Zhu XQ. Ascaris suum: RNAi mediated silencing of enolase gene expression in infective larvae. Exp Parasitol 2010; 127:142-6. [PMID: 20691683 DOI: 10.1016/j.exppara.2010.07.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 07/07/2010] [Accepted: 07/15/2010] [Indexed: 02/07/2023]
Abstract
Ascaris suum is an important parasite of pigs that causes tremendous economic losses globally to agriculture and animal husbandry annually. RNA interference (RNAi) technology has been described as a successful and useful approach for the elucidation of gene function in parasitic nematodes. In the present study, RNAi was used to silence the expression of a gene encoding enolase in A. suum by soaking infective larvae in double-stranded RNA derived from an EST (representing As-enol-1) selected from an A. suum infective larvae-specific cDNA library. The mRNA levels of RNAi-treated larvae were examined by Reverse-Transcription PCR (RT-PCR) analysis. The survival of RNAi-treated larvae was compared with larvae treated with dsRNA-free culture medium. The effect of enolase depletion on the development of A. suum larvae was assessed by infecting BALB/c mice with RNAi-treated larvae. The results showed that enolase gene expression was silenced completely and the survival rate of the RNAi-treated nematodes was reduced by 20.11% (P<0.01) after soaking for 72 h. Although no significant difference was detected in the numbers of larvae recovered from the liver and lungs of infected mice 4 days post infection, RNAi knockdown of the A. suum enolase mRNA led to significant shorter larvae, indicating that loss of enolase expression may cause delays in larval development.
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Affiliation(s)
- Ning Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong Province 510642, PR China
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Zarlenga DS, Gasbarre LC. From parasite genomes to one healthy world: Are we having fun yet? Vet Parasitol 2009; 163:235-49. [PMID: 19560277 DOI: 10.1016/j.vetpar.2009.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In 1990, the Human Genome Sequencing Project was established. This laid the ground work for an explosion of sequence data that has since followed. As a result of this effort, the first complete genome of an animal, Caenorhabditis elegans was published in 1998. The sequence of Drosophila melanogaster was made available in March, 2000 and in the following year, working drafts of the human genome were generated with the completed sequence (92%) being released in 2003. Recent advancements and next-generation technologies have made sequencing common place and have infiltrated every aspect of biological research, including parasitology. To date, sequencing of 32 apicomplexa and 24 nematode genomes are either in progress or near completion, and over 600k nematode EST and 200k apicomplexa EST submissions fill the databases. However, the winds have shifted and efforts are now refocusing on how best to store, mine and apply these data to problem solving. Herein we tend not to summarize existing X-omics datasets or present new technological advances that promise future benefits. Rather, the information to follow condenses up-to-date-applications of existing technologies to problem solving as it relates to parasite research. Advancements in non-parasite systems are also presented with the proviso that applications to parasite research are in the making.
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Affiliation(s)
- Dante S Zarlenga
- USDA, ARS, ANRI Animal Parasitic Diseases Laboratory, Beltsville, MD 20705, USA.
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Abubucker S, Zarlenga DS, Martin J, Yin Y, Wang Z, McCarter JP, Gasbarree L, Wilson RK, Mitreva M. The transcriptomes of the cattle parasitic nematode Ostertagia ostartagi. Vet Parasitol 2009; 162:89-99. [PMID: 19346077 DOI: 10.1016/j.vetpar.2009.02.023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 02/13/2009] [Accepted: 02/13/2009] [Indexed: 10/21/2022]
Abstract
Ostertagia ostertagi is a gastrointestinal parasitic nematode that affects cattle and leads to a loss of production. In this study, we present the first large-scale genomic survey of O. ostertagi by the analysis of expressed transcripts from three stages of the parasite: third-stage larvae, fourth-stage larvae and adult worms. Using an in silico approach, 2284 genes were identified from over 7000 expressed sequence tags and abundant transcripts were analyzed and characterized by their functional profile. Of the 2284 genes, 66% had similarity to other known or predicted genes while the rest were novel and potentially represent genes specific to the species and/or stages. Furthermore, a subset of the novel proteins were structurally annotated and assigned putative function based on orthologs in Caenorhabditis elegans and corresponding RNA interference phenotypes. Hence, over 70% of the genes were annotated using protein sequences, domains and pathway databases. Differentially expressed transcripts from the two larval stages and their functional profiles were also studied leading to a more detailed understanding of the parasite's life-cycle. The identified transcripts are a valuable resource for genomic studies of O. ostertagi and can facilitate the design of control strategies and vaccine programs.
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Affiliation(s)
- Sahar Abubucker
- The Genome Center, Department of Genetics, Washington University School of Medicine, St. Louis, MO 63108, United States
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Ford L, Zhang J, Liu J, Hashmi S, Fuhrman JA, Oksov Y, Lustigman S. Functional analysis of the cathepsin-like cysteine protease genes in adult Brugia malayi using RNA interference. PLoS Negl Trop Dis 2009; 3:e377. [PMID: 19190745 PMCID: PMC2634747 DOI: 10.1371/journal.pntd.0000377] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 01/13/2009] [Indexed: 12/05/2022] Open
Abstract
Background Cathepsin-like enzymes have been identified as potential targets for drug or vaccine development in many parasites, as their functions appear to be essential in a variety of important biological processes within the host, such as molting, cuticle remodeling, embryogenesis, feeding and immune evasion. Functional analysis of Caenorhabditis elegans cathepsin L (Ce-cpl-1) and cathepsin Z (Ce-cpz-1) has established that both genes are required for early embryogenesis, with Ce-cpl-1 having a role in regulating in part the processing of yolk proteins. Ce-cpz-1 also has an important role during molting. Methods and Findings RNA interference assays have allowed us to verify whether the functions of the orthologous filarial genes in Brugia malayi adult female worms are similar. Treatment of B. malayi adult female worms with Bm-cpl-1, Bm-cpl-5, which belong to group Ia of the filarial cpl gene family, or Bm-cpz-1 dsRNA resulted in decreased numbers of secreted microfilariae in vitro. In addition, analysis of the intrauterine progeny of the Bm-cpl-5 or Bm-cpl Pro dsRNA- and siRNA-treated worms revealed a clear disruption in the process of embryogenesis resulting in structural abnormalities in embryos and a varied differential development of embryonic stages. Conclusions Our studies suggest that these filarial cathepsin-like cysteine proteases are likely to be functional orthologs of the C. elegans genes. This functional conservation may thus allow for a more thorough investigation of their distinct functions and their development as potential drug targets. Filarial nematodes are an important group of human pathogens, causing lymphatic filariasis and onchocerciasis, and infecting around 150 million people throughout the tropics with more than 1.5 billion at risk of infection. Control of filariasis currently relies on mass drug administration (MDA) programs using drugs which principally target the microfilarial life-cycle stage. These control programs are facing major challenges, including the absence of a drug with macrofilaricidal or permanent sterilizing activity, and the possibility of the development of drug-resistance against the drugs available. Cysteine proteases are essential enzymes which play important roles in a wide range of cellular processes, and the cathepsin-like cysteine proteases have been identified as potential targets for drug or vaccine development in many parasites. Here we have studied the function of several of the cathepsin-like enzymes in the filarial nematode, B. malayi, and demonstrate that these cysteine proteases are involved in the development of embryos, show similar functions to their counterparts in C. elegans, and therefore, provide an important target for future drug development targeted to eliminate filariasis.
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Affiliation(s)
- Louise Ford
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America.
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Abstract
The efficiency of RNA interference varies between different organisms, even among nematodes. A recent report of successful RNA interference in the nematode Panagrolaimus superbus in BMC Molecular Biology has implications for the comparative study of the functional genomics of nematode species, and prompts reflections on the choice of Caenorhabditis elegans as a model organism.
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Affiliation(s)
- Marie-Anne Félix
- Institut Jacques Monod, CNRS - Universities of Paris 7 and 6, Tour 43, 2 place Jussieu, 75251 Paris cedex 05, France.
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Improved insights into the transcriptomes of the human hookworm Necator americanus--fundamental and biotechnological implications. Biotechnol Adv 2008; 27:122-32. [PMID: 18977428 DOI: 10.1016/j.biotechadv.2008.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/04/2008] [Accepted: 10/06/2008] [Indexed: 12/25/2022]
Abstract
Hookworms of humans are blood-feeding parasitic nematodes of major socio-economic significance in a wide range of countries. They cause a neglected tropical disease (NTD) called "hookworm disease" (=necatoriasis and/or ancylostomiasis). Necator americanus is the most widely distributed hookworm of humans and is a leading cause of iron deficiency anaemia, which can cause physical and mental retardation and deaths in children as well as adverse maternal-foetal outcomes. Currently, there is a significant focus on the development of new approaches for the prevention and control of hookworms in humans. Technological advances are underpinning the discovery of drug and vaccine targets through insights into the molecular biology and genomics of these parasites and their relationship with the human host. In spite of the widespread socio-economic impacts of human necatoriasis, molecular datasets for N. americanus are scant, limiting progress in molecular research. The present article explores all currently available EST datasets for adult and larval stages of N. americanus using a semi-automated bioinformatic pipeline. In the current repertoire of molecules now available, some have been or are being considered as candidate vaccines against N. americanus. Among others, the most abundant sets of molecules relate to the pathogenesis-related protein (PRP) superfamily, comprising various members, such as the Ancylostoma-secreted or activation-associated proteins (ASPs) and the kunitz-type proteins, both of which are inferred to play key roles in the interplay between N. americanus and the human host. Understanding the molecular biology of these and other novel molecules discovered could have important implications for finding new ways of disrupting the pathways that they are involved in, and should facilitate the identification of new drug and vaccine targets. Also, the bioinformatic prediction of the essentiality of genes and gene products as well as molecular network connectivity of nematode-specific genes, together with sequencing by 454 technology, are likely to assist in the genomic discovery efforts in the very near future, to also underpin fundamental, molecular research of hookworms.
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Kang S, Hong YS. RNA interference in infectious tropical diseases. THE KOREAN JOURNAL OF PARASITOLOGY 2008; 46:1-15. [PMID: 18344671 DOI: 10.3347/kjp.2008.46.1.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Introduction of double-stranded RNA (dsRNA) into some cells or organisms results in degradation of its homologous mRNA, a process called RNA interference (RNAi). The dsRNAs are processed into short interfering RNAs (siRNAs) that subsequently bind to the RNA-induced silencing complex (RISC), causing degradation of target mRNAs. Because of this sequence-specific ability to silence target genes, RNAi has been extensively used to study gene functions and has the potential to control disease pathogens or vectors. With this promise of RNAi to control pathogens and vectors, this paper reviews the current status of RNAi in protozoans, animal parasitic helminths and disease-transmitting vectors, such as insects. Many pathogens and vectors cause severe parasitic diseases in tropical regions and it is difficult to control once the host has been invaded. Intracellularly, RNAi can be highly effective in impeding parasitic development and proliferation within the host. To fully realize its potential as a means to control tropical diseases, appropriate delivery methods for RNAi should be developed, and possible off-target effects should be minimized for specific gene suppression. RNAi can also be utilized to reduce vector competence to interfere with disease transmission, as genes critical for pathogenesis of tropical diseases are knockdowned via RNAi.
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Affiliation(s)
- Seokyoung Kang
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA.
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Shannon AJ, Tyson T, Dix I, Boyd J, Burnell AM. Systemic RNAi mediated gene silencing in the anhydrobiotic nematode Panagrolaimus superbus. BMC Mol Biol 2008; 9:58. [PMID: 18565215 PMCID: PMC2453295 DOI: 10.1186/1471-2199-9-58] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2008] [Accepted: 06/19/2008] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Gene silencing by RNA interference (RNAi) is a powerful tool for functional genomics. Although RNAi was first described in Caenorhabditis elegans, several nematode species are unable to mount an RNAi response when exposed to exogenous double stranded RNA (dsRNA). These include the satellite model organisms Pristionchus pacificus and Oscheius tipulae. Available data also suggest that the RNAi pathway targeting exogenous dsRNA may not be fully functional in some animal parasitic nematodes. The genus Panagrolaimus contains bacterial feeding nematodes which occupy a diversity of niches ranging from polar, temperate and semi-arid soils to terrestrial mosses. Thus many Panagrolaimus species are adapted to tolerate freezing and desiccation and are excellent systems to study the molecular basis of environmental stress tolerance. We investigated whether Panagrolaimus is susceptible to RNAi to determine whether this nematode could be used in large scale RNAi studies in functional genomics. RESULTS We studied two species: Panagrolaimus sp. PS1159 and Panagrolaimus superbus. Both nematode species displayed embryonic lethal RNAi phenotypes following ingestion of Escherichia coli expressing dsRNA for the C. elegans embryonic lethal genes Ce-lmn-1 and Ce-ran-4. Embryonic lethal RNAi phenotypes were also obtained in both species upon ingestion of dsRNA for the Panagrolaimus genes ef1b and rps-2. Single nematode RT-PCR showed that a significant reduction in mRNA transcript levels occurred for the target ef1b and rps-2 genes in RNAi treated Panagrolaimus sp. 1159 nematodes. Visible RNAi phenotypes were also observed when P. superbus was exposed to dsRNA for structural genes encoding contractile proteins. All RNAi phenotypes were highly penetrant, particularly in P. superbus. CONCLUSION This demonstration that Panagrolaimus is amenable to RNAi by feeding will allow the development of high throughput methods of RNAi screening for P. superbus. This greatly enhances the utility of this nematode as a model system for the study of the molecular biology of anhydrobiosis and cryobiosis and as a possible satellite model nematode for comparative and functional genomics. Our data also identify another nematode infraorder which is amenable to RNAi and provide additional information on the diversity of RNAi phenotypes in nematodes.
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Affiliation(s)
- Adam J Shannon
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Trevor Tyson
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Ilona Dix
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Jacqueline Boyd
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
- School of Animal, Rural and Environmental Sciences, Nottingham Trent University, Nottingham Rd., Southwell, NG25 0QF, UK
| | - Ann M Burnell
- Biology Department, National University of Ireland, Maynooth, Co. Kildare, Ireland
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Two hypotheses to explain why RNA interference does not work in animal parasitic nematodes. Int J Parasitol 2007; 38:43-7. [PMID: 18028931 DOI: 10.1016/j.ijpara.2007.08.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 08/15/2007] [Accepted: 08/21/2007] [Indexed: 01/18/2023]
Abstract
RNA interference (RNAi) has been used extensively in model organisms such as Caenorhabditis elegans. Methods developed for RNAi in C. elegans have also been used in parasitic nematodes. However, RNAi in parasitic nematodes has been unsuccessful or has had limited success. Studies of genes essential for RNAi in C. elegans and of RNAi in Caenorhabditis spp. other than C. elegans suggest two complementary, and testable, hypotheses for the limited success of RNAi in animal parasitic nematodes. These are: (i) that the external supply of double stranded RNA (dsRNA) to parasitic nematodes is inappropriate to achieve RNAi and (ii) that parasitic nematodes are functionally defective in genes required to initiate RNAi from externally supplied dsRNA.
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Abstract
The diseases caused by parasitic nematodes in domestic and companion animals are major factors that decrease production and quality of the agricultural products. Methods available for the control of the parasitic nematode infections are mainly based on chemical treatment, non-chemical management practices, immune modulation and biological control. However, even with integrated pest management that frequently combines these approaches, the effective and long-lasting control strategies are hampered by the persistent exposure of host animals to environmental stages of parasites, the incomplete protective response of the host and acquisition of anthelmintic resistance by an increasing number of parasitic nematodes. Therefore, the challenges to improve control of parasitic nematode infections are multi-fold and no single category of information will meet them all. However, new information, such as nematode genomics, functional genomics and proteomics, can strengthen basic and applied biological research aimed to develop improvements. In this review we will, summarize existing control strategies of nematode infections and discuss ongoing developments in nematode genomics. Genomics approaches offer a growing and fundamental base of information, which when coupled with downstream functional genomics and proteomics can accelerate progress towards developing more efficient and sustainable control programs.
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Affiliation(s)
- Makedonka Mitreva
- Genome Sequencing Center, Department of Genetics, Washington University School of Medicine, 4444 Forest Park Boulevard, St. Louis, MO 63108, USA.
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Knox DP, Geldhof P, Visser A, Britton C. RNA interference in parasitic nematodes of animals: a reality check? Trends Parasitol 2007; 23:105-7. [PMID: 17276139 DOI: 10.1016/j.pt.2007.01.007] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 12/13/2006] [Accepted: 01/16/2007] [Indexed: 11/24/2022]
Abstract
RNA interference (RNAi) is widely used in Caenorhabditis elegans to identify gene function and has been adapted as a high-throughput screening method to identify genes involved in essential processes. The technique has been applied to parasitic nematodes with variable success and we believe that inconsistent outcomes preclude its use as a robust screen with which to identify potential control targets. In this article, key issues that require clarification are discussed, including the mode of delivery of double-stranded RNA to the parasite, the developmental stage targeted and, perhaps of most importance, whether the RNAi pathway (as defined by studies in C. elegans) is fully functional in some parasitic nematodes.
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Affiliation(s)
- David P Knox
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK.
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