scholarly journals Newly identified parasitic nematode beta-tubulin alleles confer resistance to benzimidazoles

2021 ◽  
Author(s):  
Clayton Dilks ◽  
Emily Koury ◽  
Claire Buchanan ◽  
Erik Andersen
Keyword(s):  
Parasitic Nematode ◽  
Parasitic Nematodes ◽  
Beta Tubulin ◽  
Resistance Phenotype ◽  
C Elegans ◽  
Fitness Consequences ◽  
Parasite Populations ◽  
Seven Generations ◽  
New Alleles ◽  
Anthelmintic Drugs

Infections by parasitic nematodes cause large health and economic burdens worldwide. We use anthelmintic drugs to reduce these infections. However, resistance to anthelmintic drugs is extremely common and increasing worldwide. It is essential to understand the mechanisms of resistance to slow its spread. Recently, four new parasitic nematode beta-tubulin alleles have been identified in benzimidazole (BZ) resistant parasite populations: E198I, E198K, E198T, and E198stop. These alleles have not been tested for the ability to confer resistance or for any effects that they might have on organismal fitness. We introduced these four new alleles into the sensitive C. elegans laboratory-adapted N2 strain and exposed these genome-edited strains to both albendazole and fenbendazole. We found that all four alleles conferred resistance to both BZ drugs. Additionally, we tested for fitness consequences in both control and albendazole conditions over seven generations in competitive fitness assays. We found that none of the edited alleles had deleterious effects on fitness in control conditions and that all four alleles conferred strong and equivalent fitness benefits in BZ drug conditions. Because it is unknown if previously validated alleles confer a dominant or recessive BZ resistance phenotype, we tested the phenotypes caused by five of these alleles and found that none of them conferred a dominant BZ resistance phenotype. Accurate measurements of resistance, fitness effects, and dominance caused by the resistance alleles allow for the generation of better models of population dynamics and facilitate control practices that maximize the efficacy of this critical anthelmintic drug class.

The use of Caenorhabditis elegans in parasitic nematode research

Parasitology ◽  
2004 ◽  
Vol 128 (S1) ◽  
pp. S49-S70 ◽  
Author(s):  
J. S. GILLEARD
Keyword(s):  
Caenorhabditis Elegans ◽  
Parasitic Nematode ◽  
Expression System ◽  
Nematode Species ◽  
Current Status ◽  
Evolutionary Development ◽  
Parasitic Nematodes ◽  
Free Living ◽  
C Elegans ◽  
Free Living Nematode

There is increasing interest in the use of the free-living nematode Caenorhabditis elegans as a tool for parasitic nematode research and there are now a number of compelling examples of its successful application. C. elegans has the potential to become a standard tool for molecular helminthology researchers, just as yeast is routinely used by molecular biologists to study vertebrate biology. However, in order to exploit C. elegans in a meaningful manner, we need a detailed understanding of the extent to which different aspects of C. elegans biology have been conserved with particular groups of parasitic nematodes. This review first considers the current state of knowledge regarding the conservation of genome organisation across the nematode phylum and then discusses some recent evolutionary development studies in free-living nematodes. The aim is to provide some important concepts that are relevant to the extrapolation of information from C. elegans to parasitic nematodes and also to the interpretation of experiments that use C. elegans as a surrogate expression system. In general, examples have been specifically chosen because they highlight the importance of careful experimentation and interpretation of data. Consequently, the focus is on the differences that have been found between nematode species rather than the similarities. Finally, there is a detailed discussion of the current status of C. elegans as a heterologous expression system to study parasite gene function and regulation using successful examples from the literature.

scholarly journals Caenorhabditis elegans: nature and nurture gift to nematode parasitologists

Parasitology ◽  
2017 ◽  
Vol 145 (8) ◽  
pp. 979-987 ◽  
Author(s):  
Gustavo Salinas ◽  
Gastón Risi
Keyword(s):  
Animal Model ◽  
Caenorhabditis Elegans ◽  
Parasitic Nematode ◽  
Model Organism ◽  
Parasitic Nematodes ◽  
Free Living ◽  
C Elegans ◽  
Free Living Nematode ◽  
Basic Biology ◽  
Nature And Nurture

AbstractThe free-living nematode Caenorhabditis elegans is the simplest animal model organism to work with. Substantial knowledge and tools have accumulated over 50 years of C. elegans research. The use of C. elegans relating to parasitic nematodes from a basic biology standpoint or an applied perspective has increased in recent years. The wealth of information gained on the model organism, the use of the powerful approaches and technologies that have advanced C. elegans research to parasitic nematodes and the enormous success of the omics fields have contributed to bridge the divide between C. elegans and parasite nematode researchers. We review key fields, such as genomics, drug discovery and genetics, where C. elegans and nematode parasite research have convened. We advocate the use of C. elegans as a model to study helminth metabolism, a neglected area ready to advance. How emerging technologies being used in C. elegans can pave the way for parasitic nematode research is discussed.

Complementary Approaches to Understand Anthelmintic Resistance Using Free-Living and Parasitic Nematodes

2020 ◽  
Author(s):  
Janneke Wit ◽  
Clayton Dilks ◽  
Erik Andersen
Keyword(s):  
Haemonchus Contortus ◽  
Parasitic Nematode ◽  
Anthelmintic Resistance ◽  
Animal Health ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Mechanisms Of Resistance ◽  
Free Living ◽  
Powerful Approach ◽  
Anthelmintic Drugs

Parasitic nematode infections impact human and animal health globally, especially in the developing world. Anthelmintic drugs are the major line of defense against these infections, but the arsenal is limited. Additionally, anthelmintic resistance is widespread in veterinary parasites and an emerging threat in human parasites. Discoveries of the mode of action of these drugs and mechanisms of resistance have predominantly come from studies of a related non-parasitic nematode species, Caenorhabditis elegans, and the parasitic nematode Haemonchus contortus. Here, we discuss recent progress understanding anthelmintic resistance using these two species and how that progress relates to laboratory and field-based studies of veterinary helminths. We present a powerful approach enabled by the strengths of both nematode species to understand mechanisms of resistance and modes of action of anthelmintic drugs.

scholarly journals Discovery of unique loci that underlie nematode responses to benzimidazoles

2017 ◽  
Author(s):  
Mostafa Zamanian ◽  
Daniel E. Cook ◽  
Stefan Zdraljevic ◽  
Shannon C. Brady ◽  
Daehan Lee ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Resistance Genes ◽  
Anthelmintic Resistance ◽  
Benzimidazole Derivatives ◽  
Parasitic Nematodes ◽  
C Elegans ◽  
Benzimidazole Resistance ◽  
Drug Classes ◽  
Parasite Populations ◽  
Parasite Drug Resistance

Parasitic nematodes impose a debilitating health and economic burden across much of the world. Nematode resistance to anthelmintic drugs threatens parasite control efforts in both human and veterinary medicine. Despite this threat, the genetic landscape of potential resistance mechanisms to these critical drugs remains largely unexplored. Here, we exploit natural variation in the model nematodes Caenorhabditis elegans and Caenorhabditis briggsae to discover quantitative trait loci (QTL) that control sensitivity to benzimidazoles widely used in human and animal medicine. High-throughput phenotyping of albendazole, fenbendazole, mebendazole, and thiabendazole responses in panels of recombinant lines led to the discovery of over 15 QTL in C. elegans and four QTL in C. briggsae associated with divergent responses to these anthelmintics. Many of these QTL are conserved across benzimidazole derivatives, but others show drug and dose specificity. We used near-isogenic lines to recapitulate and narrow the C. elegans albendazole QTL of largest effect and identified candidate variants correlated with the resistance phenotype. These QTL do not overlap with known benzimidazole resistance genes from parasitic nematodes and present specific new leads for the discovery of novel mechanisms of nematode benzimidazole resistance. Analyses of orthologous genes reveal significant conservation of candidate benzimidazole resistance genes in medically important parasitic nematodes. These data provide a basis for extending these approaches to other anthelmintic drug classes and a pathway towards validating new markers for anthelmintic resistance that can be deployed to improve parasite disease control.Author SummaryThe treatment of roundworm (nematode) infections in both humans and animals relies on a small number of anti-parasitic drugs. Resistance to these drugs has appeared in veterinary parasite populations and is a growing concern in human medicine. A better understanding of the genetic basis for parasite drug resistance can be used to help maintain the effectiveness of anti-parasitic drugs and to slow or to prevent the spread of drug resistance in parasite populations. This goal is hampered by the experimental intractability of nematode parasites. Here, we use non-parasitic model nematodes to systematically explore responses to the critical benzimidazole class of anti-parasitic compounds. Using a quantitative genetics approach, we discovered unique genomic intervals that control drug effects, and we identified differences in the genetic architectures of drug responses across compounds and doses. We were able to narrow a major-effect genomic region associated with albendazole resistance and to establish that candidate genes discovered in our genetic mappings are largely conserved in important human and animal parasites. This work provides new leads for understanding parasite drug resistance and contributes a powerful template that can be extended to other anti-parasitic drug classes.

scholarly journals Two novel loci underlie natural differences in Caenorhabditis elegans macrocyclic lactone responses

2021 ◽  
Author(s):  
Kathryn S. Evans ◽  
Janneke Wit ◽  
Lewis Stevens ◽  
Steffen R. Hahnel ◽  
Briana Rodriguez ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Haemonchus Contortus ◽  
Macrocyclic Lactone ◽  
Parasitic Nematode ◽  
Anthelmintic Resistance ◽  
Recombinant Inbred Lines ◽  
Parasitic Nematodes ◽  
C Elegans ◽  
The Future ◽  
Genomic Regions

AbstractParasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes.Author SummaryParasitic nematodes infect plants, animals, and humans, causing major health and economic burdens worldwide. Parasitic nematode infections are generally treated efficiently with a class of drugs named anthelmintics. However, resistance to many of these anthelmintic drugs, including macrocyclic lactones (MLs), is rampant and increasing. Therefore, it is essential that we understand how these drugs act against parasitic nematodes and, conversely, how nematodes gain resistance in order to better treat these infections in the future. Here, we used the non-parasitic nematode Caenorhabditis elegans as a model organism to study ML resistance. We leveraged natural genetic variation between strains of C. elegans with differential responses to abamectin to identify three genomic regions on chromosome V, each containing one or more genes that contribute to ML resistance. Two of these loci have not been previously discovered and likely represent novel resistance mechanisms. We also compared the genes in these two novel loci to the genes found within genomic regions linked to ML resistance in the parasite Haemonchus contortus and found several cases of overlap between the two species. Overall, this study highlights the advantages of using C. elegans to understand anthelmintic resistance in parasitic nematodes.

scholarly journals Functional investigation of conserved glutamate receptor subunits reveals a new mode of action of macrocyclic lactones in nematodes

2020 ◽  
Author(s):  
Nicolas Lamassiaude ◽  
Elise Courtot ◽  
Angélique Corset ◽  
Claude L. Charvet ◽  
Cédric Neveu
Keyword(s):  
Caenorhabditis Elegans ◽  
Mode Of Action ◽  
Chloride Channels ◽  
Parasitic Nematode ◽  
Expression System ◽  
Molecular Targets ◽  
Parasitic Nematodes ◽  
Pharmacological Properties ◽  
Macrocyclic Lactones ◽  
C Elegans

AbstractGlutamate-gated chloride channels receptors (GluCls) are involved in the inhibition of neurotransmission in invertebrates and represent major molecular targets for therapeutic drugs. Among these drugs, macrocyclic lactones (MLs) are widely used as anthelmintic to treat parasitic nematodes impacting both human and animal health. Despite massive use of MLs since the 80’s, the exact molecular targets of these drugs are still unknown in many important parasite species. Among the GluCl subunit encoding genes, avr-14, glc-2, glc-3 and glc-4 are highly conserved throughout the nematode phylum. Using the Xenopus oocyte as an expression system, we pharmacologically characterized these GluCl subunits from the model nematode Caenorhabditis elegans, the human filarial nematode Brugia malayi and the horse parasitic nematode Parascaris univalens. In contrast with C. elegans, expression of parasitic nematode subunits as homomeric receptors was not reliable and needed glutamate application at the mM range to induce low currents at the nA range. However, the co-expression of GLC-2 and AVR-14B lead to the robust expression of ML-sensitive receptors for the three nematode species. In addition, we demonstrated that for C. elegans and P. univalens, GLC-2 co-assembled with GLC-3 to form a new GluCl subtype with distinct pharmacological properties. Whereas 1μM ivermectin, moxidectin and eprinomectin acted as agonist of the GLC-2/GLC-3 receptor from C. elegans, they did not directly activate GLC-2/GLC-3 of P. univalens. In contrast, these MLs potentialized glutamate elicited currents thus representing a unique pharmacological property. Our results highlight the importance of GLC-2 as a key subunit in the composition of heteromeric channels in nematodes and demonstrate that MLs act on novel GluCl subtypes that show unusual pharmacological properties, providing new insights about MLs mode of action.Author summaryThe filarial and ascarid parasitic nematodes include some of the most pathogenic or invalidating species in humans, livestock and companion animals. Whereas the control of these worms is critically dependent on macrocyclic lactones (MLs) such as ivermectin, the mode of action of this anthelmintic class remains largely unknown in these parasites. In the model nematode Caenorhabditis elegans, MLs target GluCl pentameric glutamate-sensitive chloride channels (GluCl). Because MLs are potent anthelmintics on C. elegans, ascarid and filarial nematodes, in the present study we investigated GluCl subunits highly conserved between these distantly related worms. Using the Xenopus oocyte as a heterologous expression system, we identified and performed the pharmacological characterization of novel GluCl receptors from C. elegans, the human filarial parasite Brugia malayi and the horse parasite Parascaris univalens. Our results highlight heteromeric GluCls from parasites as molecular targets for a wide range of MLs. We report an original mode of action of MLs on a new GluCl subtype made of the GLC-2/GLC-3 subunit combination. This study brings new insights about the diversity of GluCl subtypes in nematodes and opens the way for rational drug screening for the identification of next generation anthelmintic compounds.

Caenorhabditis elegans as a model for plant-parasitic nematodes

Nematology ◽  
2007 ◽  
Vol 9 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Peter Urwin ◽  
Catherine Lilley ◽  
Joana Costa
Keyword(s):  
Caenorhabditis Elegans ◽  
Comparative Genomics ◽  
Parasitic Nematode ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Model Species ◽  
Practical Utility ◽  
C Elegans ◽  
Available Information ◽  
Plant Parasitic

AbstractMany studies on aspects of the biology of plant-parasitic nematodes can be facilitated by using the information and resources available for the model species Caenorhabditis elegans. Comparative genomics of shared processes can provide insights into plant-parasitic nematode biology that would otherwise be intractable. In this article we consider some of the resources available for C. elegans. We describe the practical utility of C. elegans and the use of available information to facilitate the characterisation of neurobiological processes in plant-parasitic nematodes.

scholarly journals A survey of the kinome pharmacopeia reveals multiple scaffolds and targets for the development of novel anthelmintics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jessica Knox ◽  
Nicolas Joly ◽  
Edmond M. Linossi ◽  
José A. Carmona-Negrón ◽  
Natalia Jura ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Developmental Delay ◽  
Small Molecule ◽  
Parasitic Nematode ◽  
Kinase Inhibitor ◽  
Binding Pocket ◽  
Drug Binding ◽  
Nematode Infection ◽  
Selective Inhibitors ◽  
C Elegans

AbstractOver one billion people are currently infected with a parasitic nematode. Symptoms can include anemia, malnutrition, developmental delay, and in severe cases, death. Resistance is emerging to the anthelmintics currently used to treat nematode infection, prompting the need to develop new anthelmintics. Towards this end, we identified a set of kinases that may be targeted in a nematode-selective manner. We first screened 2040 inhibitors of vertebrate kinases for those that impair the model nematode Caenorhabditis elegans. By determining whether the terminal phenotype induced by each kinase inhibitor matched that of the predicted target mutant in C. elegans, we identified 17 druggable nematode kinase targets. Of these, we found that nematode EGFR, MEK1, and PLK1 kinases have diverged from vertebrates within their drug-binding pocket. For each of these targets, we identified small molecule scaffolds that may be further modified to develop nematode-selective inhibitors. Nematode EGFR, MEK1, and PLK1 therefore represent key targets for the development of new anthelmintic medicines.

scholarly journals Quantitative benzimidazole resistance and fitness effects of parasitic nematode beta-tubulin alleles

2020 ◽  
Vol 14 ◽  
pp. 28-36 ◽  
Author(s):  
Clayton M. Dilks ◽  
Steffen R. Hahnel ◽  
Qicong Sheng ◽  
Lijiang Long ◽  
Patrick T. McGrath ◽  
...  
Keyword(s):  
Parasitic Nematode ◽  
Beta Tubulin ◽  
Fitness Effects ◽  
Benzimidazole Resistance

Nematode ligand-gated chloride channels: an appraisal of their involvement in macrocyclic lactone resistance and prospects for developing molecular markers

Parasitology ◽  
2007 ◽  
Vol 134 (8) ◽  
pp. 1111-1121 ◽  
Author(s):  
S. McCAVERA ◽  
T. K. WALSH ◽  
A. J. WOLSTENHOLME
Keyword(s):  
Haemonchus Contortus ◽  
Chloride Channels ◽  
Macrocyclic Lactone ◽  
Parasitic Nematodes ◽  
C Elegans ◽  
Molecular Tests ◽  
Cooperia Oncophora ◽  
Macrocyclic Lactone Resistance ◽  
High Level ◽  
Laboratory Models

SUMMARYLigand-gated chloride channels, including the glutamate-(GluCl) and GABA-gated channels, are the targets of the macrocyclic lactone (ML) family of anthelmintics. Changes in the sequence and expression of these channels can cause resistance to the ML in laboratory models, such as Caenorhabditis elegans and Drosophila melanogaster. Mutations in multiple GluCl subunit genes are required for high-level ML resistance in C. elegans, and this can be influenced by additional mutations in gap junction and amphid genes. Parasitic nematodes have a different complement of channel subunit genes from C. elegans, but a few genes, including avr-14, are widely present. A polymorphism in an avr-14 orthologue, which makes the subunit less sensitive to ivermectin and glutamate, has been identified in Cooperia oncophora, and polymorphisms in several subunits have been reported from resistant isolates of Haemonchus contortus. This has led to suggestions that ML resistance may be polygenic. Possible reasons for this, and its consequences for the development of molecular tests for resistance, are explored.

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