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Abstract
In the last 2 decades, renewed attention to neglected tropical diseases (NTDs) has spurred the development of antiparasitic agents, especially in light of emerging drug resistance. The need for new drugs has required in vitro screening methods using parasite culture. Furthermore, clinical laboratories sought to correlate in vitro susceptibility methods with treatment outcomes, most notably with malaria. Parasites with their various life cycles present greater complexity than bacteria, for which standardized susceptibility methods exist. This review catalogs the state-of-the-art methodologies used to evaluate the effects of drugs on key human parasites from the point of view of drug discovery as well as the need for laboratory methods that correlate with clinical outcomes.
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Preston S, Gasser RB. Working towards New Drugs against Parasitic Worms in a Public-Development Partnership. Trends Parasitol 2017; 34:4-6. [PMID: 28784352 DOI: 10.1016/j.pt.2017.07.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/17/2017] [Indexed: 02/06/2023]
Abstract
There is a clear need to develop new and inexpensive drugs to alleviate diseases caused by parasitic worms in animals and humans worldwide. In this article we discuss the roles and advantages of working in public-private partnerships (PPPs) - among academia, industry, and philanthropy - to enable anthelmintic drug discovery.
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Affiliation(s)
- Sarah Preston
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia; Faculty of Science and Technology, Federation University, Ballarat, Victoria 3350, Australia.
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
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In Vitro Efficacy of Moxidectin versus Ivermectin against Sarcoptes scabiei. Antimicrob Agents Chemother 2017; 61:AAC.00381-17. [PMID: 28559258 DOI: 10.1128/aac.00381-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/22/2017] [Indexed: 10/19/2022] Open
Abstract
Moxidectin is under consideration for development as a treatment for human scabies. As some arthropods show decreased sensitivity to moxidectin relative to ivermectin, it was important to assess this for Sarcoptes scabieiIn vitro assays showed that the concentration of moxidectin required to kill 50% of mites was lower than that of ivermectin (0.5 μM versus 1.8 μM at 24 h; P < 0.0001). This finding provides further support for moxidectin as a candidate for the treatment of human scabies.
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Aguiar PHN, Fernandes NMGS, Zani CL, Mourão MM. A high-throughput colorimetric assay for detection of Schistosoma mansoni viability based on the tetrazolium salt XTT. Parasit Vectors 2017; 10:300. [PMID: 28637488 PMCID: PMC5480175 DOI: 10.1186/s13071-017-2240-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/11/2017] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Schistosoma mansoni is a trematode parasite that causes schistosomiasis, one of the most prevalent neglected tropical diseases, leading to the loss of 2.6 million disability-adjusted life years. Praziquantel is the only drug available, and new drugs are required. The most common strategy in schistosomiasis drug discovery is the use of the schistosomula larval-stage for a pre-screen in drug sensitivity assays. However, assessing schistosomula viability by microscopy has always been a limitation to the throughput of such assays. Hence, the development of validated, robust high-throughput in vitro assays for Schistosoma with simple readouts is needed. Here, we present a simple and affordable alternative to assess schistosomula viability. The method employed is based on the hydrosoluble tetrazolium salt XTT which has been widely used in other organisms but has never been used to drug screen in schistosomes. RESULTS We showed that schistosomula reduce XTT salt to a coloured formazan product and that absorbance levels reflected the viability and parasites number. This XTT viability assay was validated for high throughput screening of compounds in schistosomula, and dose-response curves of compounds could be reproduced. CONCLUSIONS We conclude that the XTT viability assay could be applied for the screening of large compounds collections in S. mansoni and accelerate the identification of novel antischistosomal compounds.
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Affiliation(s)
| | | | - Carlos Leomar Zani
- Laboratório de Química dos Produtos Naturais, René Rachou Research Center, FIOCRUZ, Belo Horizonte, Minas Gerais Brazil
| | - Marina Moraes Mourão
- Laboratório de Helmintologia e Malacologia Médica, René Rachou Research Center, FIOCRUZ, Belo Horizonte, Minas Gerais Brazil
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Preston S, Jiao Y, Baell JB, Keiser J, Crawford S, Koehler AV, Wang T, Simpson MM, Kaplan RM, Cowley KJ, Simpson KJ, Hofmann A, Jabbar A, Gasser RB. Screening of the 'Open Scaffolds' collection from Compounds Australia identifies a new chemical entity with anthelmintic activities against different developmental stages of the barber's pole worm and other parasitic nematodes. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:286-294. [PMID: 28732272 PMCID: PMC5517787 DOI: 10.1016/j.ijpddr.2017.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/23/2017] [Accepted: 05/25/2017] [Indexed: 12/26/2022]
Abstract
The discovery and development of novel anthelmintic classes is essential to sustain the control of socioeconomically important parasitic worms of humans and animals. With the aim of offering novel, lead-like scaffolds for drug discovery, Compounds Australia released the 'Open Scaffolds' collection containing 33,999 compounds, with extensive information available on the physicochemical properties of these chemicals. In the present study, we screened 14,464 prioritised compounds from the 'Open Scaffolds' collection against the exsheathed third-stage larvae (xL3s) of Haemonchus contortus using recently developed whole-organism screening assays. We identified a hit compound, called SN00797439, which was shown to reproducibly reduce xL3 motility by ≥ 70%; this compound induced a characteristic, "coiled" xL3 phenotype (IC50 = 3.46-5.93 μM), inhibited motility of fourth-stage larvae (L4s; IC50 = 0.31-12.5 μM) and caused considerable cuticular damage to L4s in vitro. When tested on other parasitic nematodes in vitro, SN00797439 was shown to inhibit (IC50 = 3-50 μM) adults of Ancylostoma ceylanicum (hookworm) and first-stage larvae of Trichuris muris (whipworm) and eventually kill (>90%) these stages. Furthermore, this compound completely inhibited the motility of female and male adults of Brugia malayi (50-100 μM) as well as microfilariae of both B. malayi and Dirofilaria immitis (heartworm). Overall, these results show that SN00797439 acts against genetically (evolutionarily) distant parasitic nematodes i.e. H. contortus and A. ceylanicum [strongyloids] vs. B. malayi and D. immitis [filarioids] vs. T. muris [enoplid], and, thus, might offer a novel, lead-like scaffold for the development of a relatively broad-spectrum anthelmintic. Our future work will focus on assessing the activity of SN00797439 against other pathogens that cause neglected tropical diseases, optimising analogs with improved biological activities and characterising their targets.
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Affiliation(s)
- Sarah Preston
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia; Faculty of Science and Technology, Federation University, Ballarat, Victoria 3350, Australia
| | - Yaqing Jiao
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Jonathan B Baell
- Monash University Institute of Pharmaceutical Sciences (MIPS), Monash University, Parkville, Victoria, Australia
| | - Jennifer Keiser
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Simon Crawford
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Anson V Koehler
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Tao Wang
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Moana M Simpson
- Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, Queensland, Australia
| | - Ray M Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, The University of Georgia, Athens, GA, USA
| | - Karla J Cowley
- Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Parkville, Victoria, Australia
| | - Kaylene J Simpson
- Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Parkville, Victoria, Australia; The Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia
| | - Andreas Hofmann
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia; Griffith Institute for Drug Discovery, Griffith University, Don Young Road, Nathan, Queensland, Australia
| | - Abdul Jabbar
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
| | - Robin B Gasser
- Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
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Verma S, Kashyap SS, Robertson AP, Martin RJ. Functional genomics in Brugia malayi reveal diverse muscle nAChRs and differences between cholinergic anthelmintics. Proc Natl Acad Sci U S A 2017; 114:5539-5544. [PMID: 28487481 PMCID: PMC5448196 DOI: 10.1073/pnas.1619820114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many techniques for studying functional genomics of important target sites of anthelmintics have been restricted to Caenorhabditis elegans because they have failed when applied to animal parasites. To overcome these limitations, we have focused our research on the human nematode parasite Brugia malayi, which causes elephantiasis. Here, we combine single-cell PCR, whole muscle cell patch clamp, motility phenotyping (Worminator), and dsRNA for RNAi for functional genomic studies that have revealed, in vivo, four different muscle nAChRs (M-, L-, P-, and N-). The cholinergic anthelmintics had different selectivities for these receptors. We show that motility and patch-clamp responses to levamisole and pyrantel, but not morantel or nicotine, require the unc-38 and/or unc-29 genes. Derquantel behaved as a competitive antagonist and distinguished M-nAChRs activated by morantel (Kb 13.9 nM), P-nAChRs activated by pyrantel (Kb 126 nM), and L-nAChRs activated by levamisole (Kb 0.96 µM) and bephenium. Derquantel was a noncompetitive antagonist of nicotine, revealing N-type nAChRs. The presence of four diverse nAChRs on muscle is perhaps surprising and not predicted from the C. elegans model. The diverse nAChRs represent distinguishable drug targets with different functions: Knockdown of unc-38+unc-29 (L- and/or P-receptors) inhibited motility but knockdown of acr-16+acr-26 (M- and/or N-receptors) did not.
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Affiliation(s)
- Saurabh Verma
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011
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Ritler D, Rufener R, Sager H, Bouvier J, Hemphill A, Lundström-Stadelmann B. Development of a movement-based in vitro screening assay for the identification of new anti-cestodal compounds. PLoS Negl Trop Dis 2017; 11:e0005618. [PMID: 28520724 PMCID: PMC5448807 DOI: 10.1371/journal.pntd.0005618] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/30/2017] [Accepted: 05/02/2017] [Indexed: 11/18/2022] Open
Abstract
Intestinal cestodes are infecting millions of people and livestock worldwide, but treatment is mainly based on one drug: praziquantel. The identification of new anti-cestodal compounds is hampered by the lack of suitable screening assays. It is difficult, or even impossible, to evaluate drugs against adult cestodes in vitro due to the fact that these parasites cannot be cultured in microwell plates, and adult and larval stages in most cases represent different organisms in terms of size, morphology, and metabolic requirements. We here present an in vitro-drug screening assay based on Echinococcus multilocularis protoscoleces, which represent precursors of the scolex (hence the anterior part) of the adult tapeworm. This movement-based assay can serve as a model for an adult cestode screen. Protoscoleces are produced in large numbers in Mongolian gerbils and mice, their movement is measured and quantified by image analysis, and active compounds are directly assessed in terms of morphological effects. The use of the 384-well format minimizes the amount of parasites and compounds needed and allows rapid screening of a large number of chemicals. Standard drugs showed the expected dose-dependent effect on movement and morphology of the protoscoleces. Interestingly, praziquantel inhibited movement only partially within 12 h of treatment (at concentrations as high as 100 ppm) and did thus not act parasiticidal, which was also confirmed by trypan blue staining. Enantiomers of praziquantel showed a clear difference in their minimal inhibitory concentration in the motility assay and (R)-(-)-praziquantel was 185 times more active than (S)-(-)-praziquantel. One compound named MMV665807, which was obtained from the open access MMV (Medicines for Malaria Venture) Malaria box, strongly impaired motility and viability of protoscoleces. Corresponding morphological alterations were visualized by scanning electron microscopy, and demonstrated that this compound exhibits a mode of action clearly distinct from praziquantel. Thus, MMV665807 represents an interesting lead for further evaluation. Tapeworms (cestodes) are a medically important group of helminths that infect humans and animals all around the globe. The clinical signs caused by intestinal infection with adult cestodes are mostly mild, in contrast to the more severe disease symptoms inflicted by infection with the tissue-dwelling larval stages of the same species. Praziquantel is the main drug in use against intestinal cestode infections. Development of resistance and treatment failures have been reported in trematodes, and are expected to become a problem in the future also in the case of cestode infections. Therefore, new treatment options against intestinal helminths are needed. To date, there is no in vitro-based whole-organism screening assay available that allows screening of candidate drugs with potential activity against adult cestodes. We established and characterized of a screening assay in 384-well format, which serves as a model for adult stage parasites by using Echinococcus multilocularis protoscoleces and their loss of motility as a read-out. This novel assay showed that drugs with known activity against adult cestodes inhibited motility of protoscoleces. The movement-based assay identified MMV665807 as a novel compound with profound activity against protoscoleces, and potentially also adult cestodes. Light- and electron microscopical assessments of protoscoleces treated with praziquantel and MMV665807 point towards different modes of action of the two drugs.
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Affiliation(s)
- Dominic Ritler
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | - Reto Rufener
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
| | | | | | - Andrew Hemphill
- Institute of Parasitology, Vetsuisse Faculty, University of Berne, Berne, Switzerland
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Myburgh E, Ritchie R, Goundry A, O’Neill K, Marchesi F, Devaney E. Attempts to Image the Early Inflammatory Response during Infection with the Lymphatic Filarial Nematode Brugia pahangi in a Mouse Model. PLoS One 2016; 11:e0168602. [PMID: 27992545 PMCID: PMC5161388 DOI: 10.1371/journal.pone.0168602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/02/2016] [Indexed: 11/30/2022] Open
Abstract
Helminth parasites remain a major constraint upon human health and well-being in many parts of the world. Treatment of these infections relies upon a very small number of therapeutics, most of which were originally developed for use in animal health. A lack of high throughput screening systems, together with limitations of available animal models, has restricted the development of novel chemotherapeutics. This is particularly so for filarial nematodes, which are long-lived parasites with a complex cycle of development. In this paper, we describe attempts to visualise the immune response elicited by filarial parasites in infected mice using a non-invasive bioluminescence imaging reagent, luminol, our aim being to determine whether such a model could be developed to discriminate between live and dead worms for in vivo compound screening. We show that while imaging can detect the immune response elicited by early stages of infection with L3, it was unable to detect the presence of adult worms or, indeed, later stages of infection with L3, despite the presence of worms within the lymphatic system of infected animals. In the future, more specific reagents that detect secreted products of adult worms may be required for developing screens based upon live imaging of infected animals.
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Affiliation(s)
- Elmarie Myburgh
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail: (EM); (ED); (FM)
| | - Ryan Ritchie
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Amy Goundry
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kerry O’Neill
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Garscube Estate, Glasgow, United Kingdom
| | - Francesco Marchesi
- School of Veterinary Medicine, University of Glasgow, Garscube Estate, Glasgow
- * E-mail: (EM); (ED); (FM)
| | - Eileen Devaney
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Garscube Estate, Glasgow, United Kingdom
- * E-mail: (EM); (ED); (FM)
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Wolstenholme AJ, Maclean MJ, Coates R, McCoy CJ, Reaves BJ. How do the macrocyclic lactones kill filarial nematode larvae? INVERTEBRATE NEUROSCIENCE 2016; 16:7. [PMID: 27279086 DOI: 10.1007/s10158-016-0190-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/30/2016] [Indexed: 12/17/2022]
Abstract
The macrocyclic lactones (MLs) are one of the few classes of drug used in the control of the human filarial infections, onchocerciasis and lymphatic filariasis, and the only one used to prevent heartworm disease in dogs and cats. Despite their importance in preventing filarial diseases, the way in which the MLs work against these parasites is unclear. In vitro measurements of nematode motility have revealed a large discrepancy between the maximum plasma concentrations achieved after drug administration and the amounts required to paralyze worms. Recent evidence has shed new light on the likely functions of the ML target, glutamate-gated chloride channels, in filarial nematodes and supports the hypothesis that the rapid clearance of microfilariae that follows treatment involves the host immune system.
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Affiliation(s)
- Adrian J Wolstenholme
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA. .,Department of Infectious Diseases, College of Veterinary Medicine, 501 D. W. Brooks Drive, Athens, GA, 30602, USA.
| | - Mary J Maclean
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
| | - Ruby Coates
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.,Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Ciaran J McCoy
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA.,School of Biological Sciences, Medical Biology Centre, Queen's University, 97 Lisburn Road, Belfast, BT9 7BL, UK
| | - Barbara J Reaves
- Department of Infectious Diseases and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, 30602, USA
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Preston S, Jabbar A, Gasser RB. A perspective on genomic-guided anthelmintic discovery and repurposing using Haemonchus contortus. INFECTION GENETICS AND EVOLUTION 2016; 40:368-373. [DOI: 10.1016/j.meegid.2015.06.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/28/2015] [Accepted: 06/29/2015] [Indexed: 02/02/2023]
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Practical and low cost whole-organism motility assay: A step-by-step protocol. Mol Cell Probes 2016; 30:13-7. [DOI: 10.1016/j.mcp.2015.08.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 08/25/2015] [Accepted: 08/25/2015] [Indexed: 01/09/2023]
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Kotze A, Prichard R. Anthelmintic Resistance in Haemonchus contortus: History, Mechanisms and Diagnosis. ADVANCES IN PARASITOLOGY 2016; 93:397-428. [PMID: 27238009 DOI: 10.1016/bs.apar.2016.02.012] [Citation(s) in RCA: 171] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Haemonchus contortus has shown a great ability to develop resistance to anthelmintic drugs. In many instances, resistance has appeared less than 10years after the introduction of a new drug class. Field populations of this species now show resistance to all major anthelmintic drug classes, including benzimidazoles (BZs), imidazothiazoles and macrocyclic lactones. In addition, resistance to the recently introduced amino-acetonitrile derivative class (monepantel) has already been reported. The existence of field populations showing resistance to all three major drug classes, and the early appearance of resistance to monepantel, threatens the sustainability of sheep and goat production systems worldwide. This chapter reviews the history of the development of resistance to the various anthelmintics in H. contortus and examines the mechanisms utilized by this species to resist the effects of these drugs. Some of these mechanisms are well understood, particularly for BZ drugs, while our knowledge and understanding of others are increasing. Finally, we summarize methods available for the diagnosis of resistance. While such diagnosis currently relies largely on the faecal egg count reduction test, which suffers from issues of expense and sensitivity, we describe past and current efforts to utilize cheaper and less laborious phenotypic assays with free-living life stages, and then describe progress on the development of molecular assays to provide sensitive resistance-detection tests.
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Expression of nicotinic acetylcholine receptor subunits from parasitic nematodes in Caenorhabditis elegans. Mol Biochem Parasitol 2015; 204:44-50. [PMID: 26747395 DOI: 10.1016/j.molbiopara.2015.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/09/2015] [Accepted: 12/23/2015] [Indexed: 01/18/2023]
Abstract
The levamisole-sensitive nicotinic acetylcholine receptor present at nematode neuromuscular junctions is composed of multiple different subunits, with the exact composition varying between species. We tested the ability of two well-conserved nicotinic receptor subunits, UNC-38 and UNC-29, from Haemonchus contortus and Ascaris suum to rescue the levamisole-resistance and locomotion defects of Caenorhabditis elegans strains with null deletion mutations in the unc-38 and unc-29 genes. The parasite cDNAs were cloned downstream of the relevant C. elegans promoters and introduced into the mutant strains via biolistic transformation. The UNC-38 subunit of H. contortus was able to completely rescue both the locomotion defects and levamisole resistance of the null deletion mutant VC2937 (ok2896), but no C. elegans expressing the A. suum UNC-38 could be detected. The H. contortus UNC-29.1 subunit partially rescued the levamisole resistance of a C. elegans null mutation in unc-29 VC1944 (ok2450), but did cause increased motility in a thrashing assay. In contrast, only a single line of worms containing the A. suum UNC-29 subunit showed a partial rescue of levamisole resistance, with no effect on thrashing.
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Courtot E, Charvet CL, Beech RN, Harmache A, Wolstenholme AJ, Holden-Dye L, O’Connor V, Peineau N, Woods DJ, Neveu C. Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes. PLoS Pathog 2015; 11:e1005267. [PMID: 26625142 PMCID: PMC4666645 DOI: 10.1371/journal.ppat.1005267] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 10/20/2015] [Indexed: 01/06/2023] Open
Abstract
Acetylcholine receptors are pentameric ligand-gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR.
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Affiliation(s)
- Elise Courtot
- INRA, UMR1282 Infectiologie et Santé Publique, Nouzilly, France
- Université de François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France
| | - Claude L. Charvet
- INRA, UMR1282 Infectiologie et Santé Publique, Nouzilly, France
- Université de François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France
| | - Robin N. Beech
- INRA, UMR1282 Infectiologie et Santé Publique, Nouzilly, France
- Institute of Parasitology, McGill University, Macdonald Campus, Sainte Anne de Bellevue, Québec, Canada
| | - Abdallah Harmache
- INRA, UMR1282 Infectiologie et Santé Publique, Nouzilly, France
- Université de François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France
| | - Adrian J. Wolstenholme
- Department of Infectious Disease and Center for Tropical and Emerging Global Disease, University of Georgia, Athens, Georgia, United States of America
| | - Lindy Holden-Dye
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Vincent O’Connor
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Nicolas Peineau
- Université François Rabelais de Tours, Département de physiologie animale, Tours, France
| | - Debra J. Woods
- Veterinary Medicine Research and Development, Zoetis LLC, Kalamazoo, Michigan, United States of America
| | - Cedric Neveu
- INRA, UMR1282 Infectiologie et Santé Publique, Nouzilly, France
- Université de François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France
- * E-mail:
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Mostafa E, Storey B, Farghaly AM, Afify HAEH, Taha AAER, Wolstenholme AJ. Transient effects of levamisole on Brugia malayi microfilariae. INVERTEBRATE NEUROSCIENCE 2015; 15:5. [PMID: 26187649 DOI: 10.1007/s10158-015-0181-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 07/09/2015] [Indexed: 11/30/2022]
Abstract
Levamisole is an anthelmintic drug that acts by activating nicotinic acetylcholine receptors at the nematode neuromuscular junction and causing paralysis. We measured the in vitro effects of levamisole on the motility of Brugia malayi microfilariae; after 2 h incubation the apparent IC50 was 2.68 mM. Lower drug concentrations, such as 1 mM, caused an immediate total paralysis that lasted for up to 1 h, but was completely reversed by 2 h of incubation. The 'recovered' parasites were still completely susceptible to application of a second nicotinic agonist, pyrantel.
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Affiliation(s)
- Eman Mostafa
- Department of Infectious Diseases, University of Georgia, 501 D.W. Brooks Drive, Athens, GA, 30602, USA
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D'Ambrosio MV, Bakalar M, Bennuru S, Reber C, Skandarajah A, Nilsson L, Switz N, Kamgno J, Pion S, Boussinesq M, Nutman TB, Fletcher DA. Point-of-care quantification of blood-borne filarial parasites with a mobile phone microscope. Sci Transl Med 2015; 7:286re4. [PMID: 25947164 PMCID: PMC11005326 DOI: 10.1126/scitranslmed.aaa3480] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Parasitic helminths cause debilitating diseases that affect millions of people in primarily low-resource settings. Efforts to eliminate onchocerciasis and lymphatic filariasis in Central Africa through mass drug administration have been suspended because of ivermectin-associated serious adverse events, including death, in patients infected with the filarial parasite Loa loa. To safely administer ivermectin for onchocerciasis or lymphatic filariasis in regions co-endemic with L. loa, a strategy termed "test and (not) treat" has been proposed whereby those with high levels of L. loa microfilariae (>30,000/ml) that put them at risk for life-threatening serious adverse events are identified and excluded from mass drug administration. To enable this, we developed a mobile phone-based video microscope that automatically quantifies L. loa microfilariae in whole blood loaded directly into a small glass capillary from a fingerprick without the need for conventional sample preparation or staining. This point-of-care device automatically captures and analyzes videos of microfilarial motion in whole blood using motorized sample scanning and onboard motion detection, minimizing input from health care workers and providing a quantification of microfilariae per milliliter of whole blood in under 2 min. To validate performance and usability of the mobile phone microscope, we tested 33 potentially Loa-infected patients in Cameroon and confirmed that automated counts correlated with manual thick smear counts (94% specificity; 100% sensitivity). Use of this technology to exclude patients from ivermectin-based treatment at the point of care in Loa-endemic regions would allow resumption/expansion of mass drug administration programs for onchocerciasis and lymphatic filariasis in Central Africa.
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Affiliation(s)
- Michael V D'Ambrosio
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA
| | - Matthew Bakalar
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA
| | - Sasisekhar Bennuru
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA
| | - Clay Reber
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA
| | - Arunan Skandarajah
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA
| | - Lina Nilsson
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA
| | - Neil Switz
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA. Biophysics Graduate Group, UC Berkeley, Berkeley, CA 94720, USA
| | - Joseph Kamgno
- Center for Research on Filariasis and other Tropical Diseases, Yaoundé, Cameroon. Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - Sébastien Pion
- Center for Research on Filariasis and other Tropical Diseases, Yaoundé, Cameroon. UMI 233, Institut de Recherche pour le Développement and University of Montpellier, Montpellier, France
| | - Michel Boussinesq
- UMI 233, Institut de Recherche pour le Développement and University of Montpellier, Montpellier, France
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
| | - Daniel A Fletcher
- Department of Bioengineering, University of California (UC), Berkeley, Berkeley, CA 94720, USA. Biophysics Graduate Group, UC Berkeley, Berkeley, CA 94720, USA.
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Buckingham SD, Partridge FA, Sattelle DB. Automated, high-throughput, motility analysis in Caenorhabditis elegans and parasitic nematodes: Applications in the search for new anthelmintics. Int J Parasitol Drugs Drug Resist 2014; 4:226-32. [PMID: 25516833 PMCID: PMC4266775 DOI: 10.1016/j.ijpddr.2014.10.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The scale of the damage worldwide to human health, animal health and agricultural crops resulting from parasitic nematodes, together with the paucity of treatments and the threat of developing resistance to the limited set of widely-deployed chemical tools, underlines the urgent need to develop novel drugs and chemicals to control nematode parasites. Robust chemical screens which can be automated are a key part of that discovery process. Hitherto, the successful automation of nematode behaviours has been a bottleneck in the chemical discovery process. As the measurement of nematode motility can provide a direct scalar readout of the activity of the neuromuscular system and an indirect measure of the health of the animal, this omission is acute. Motility offers a useful assay for high-throughput, phenotypic drug/chemical screening and several recent developments have helped realise, at least in part, the potential of nematode-based drug screening. Here we review the challenges encountered in automating nematode motility and some important developments in the application of machine vision, statistical imaging and tracking approaches which enable the automated characterisation of nematode movement. Such developments facilitate automated screening for new drugs and chemicals aimed at controlling human and animal nematode parasites (anthelmintics) and plant nematode parasites (nematicides).
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Affiliation(s)
| | | | - David B. Sattelle
- Wolfson Institute for Biomedical Research, Division of Medicine, University College London, Cruciform Building, Gower Street, London WC1E 6BT, United Kingdom
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Wolstenholme AJ, Martin RJ. Anthelmintics - from discovery to resistance. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2014; 4:218-9. [PMID: 25516831 PMCID: PMC4266783 DOI: 10.1016/j.ijpddr.2014.10.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Special Issue from the “Anthelmintics: From Discovery to Resistance” meeting, San Francisco, February 2014. Meeting themes: drug discovery, modes of action and resistance. Human and veterinary parasites covered. Academic and industrial attendees.
The scientific meeting entitled ‘Anthelmintics: From Discovery to Resistance’ was held in San Francisco in February 2014. The themes of the meeting were drug discovery, modes of action and resistance. Both human and veterinary parasites were covered in the oral and poster presentations. The attendees were from both academic and industrial backgrounds. In the present article we introduce a number of the papers that emerged from the meeting. Several of the papers covered current drug discovery efforts underway worldwide, with some specific examples focusing on ion channels, protein kinases and cysteine proteases. These efforts included the repurposing of known drugs as well as the discovery of novel actives. Two papers described recently-developed whole-organism screening techniques. Finally, we introduce several papers looking at mechanisms and management of drug resistance in human and veterinary parasites.
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Affiliation(s)
- Adrian J Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA ; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Richard J Martin
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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