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Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()

Resistance to the anthelmintic drug monepantel (Zolvix(®)) has emerged in parasitic worms infecting sheep and goats. The mechanism of resistance in these cases is unknown. The drug targets nicotinic acetylcholine receptors belonging to the nematode-specific DEG-3 subfamily. We examined the receptor...

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Autores principales: Bagnall, Neil H., Ruffell, Angela, Raza, Ali, Elliott, Timothy P., Lamb, Jane, Hunt, Peter W., Kotze, Andrew C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5430491/
https://www.ncbi.nlm.nih.gov/pubmed/28501715
http://dx.doi.org/10.1016/j.ijpddr.2017.05.001
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author Bagnall, Neil H.
Ruffell, Angela
Raza, Ali
Elliott, Timothy P.
Lamb, Jane
Hunt, Peter W.
Kotze, Andrew C.
author_facet Bagnall, Neil H.
Ruffell, Angela
Raza, Ali
Elliott, Timothy P.
Lamb, Jane
Hunt, Peter W.
Kotze, Andrew C.
author_sort Bagnall, Neil H.
collection PubMed
description Resistance to the anthelmintic drug monepantel (Zolvix(®)) has emerged in parasitic worms infecting sheep and goats. The mechanism of resistance in these cases is unknown. The drug targets nicotinic acetylcholine receptors belonging to the nematode-specific DEG-3 subfamily. We examined the receptor gene, Hco-mptl-1, in a highly Zolvix(®)-resistant and a -susceptible isolate of the parasitic nematode Haemonchus contortus. cDNA coding for the full length receptor protein (Hco-MPTL-1) was present in all clones prepared from a pool of susceptible larvae (21/21 clones) and approximately 50% of those from the resistant isolate (17/33). On the other hand, the remaining clones from the resistant isolate showed various mutations that resulted in truncated predicted proteins, missing at least one transmembrane domain. The most common mutation (11/33 clones) resulted in the retention of intron 15, a premature stop codon, and a truncated protein. Sequencing of intron 15 genomic DNA showed very few SNPs in susceptible larvae and in 12/18 clones from resistant larvae, alongside the presence of at least 17 SNPs in the remaining resistant clones. The present study shows that the highly resistant isolate has a number of mutations in the drug target gene that would most-likely result in a non-functional receptor, thus rendering the larvae insensitive to the drug. The presence of many wild-type sequences in this highly-resistant population suggests that there was a significant presence of heterozygotes in the survivors of the field drench treatment from which the isolate was derived, and hence that at least some of the mutations may be dominant. Alternatively, their presence may be due to the additional influence of mutations at another locus contributing to the resistance phenotype. The presence of multiple separate mutations in the Hco-mptl-1 gene in this viable field-derived worm isolate may at least partly explain why resistance to Zolvix(®) has arisen rapidly in the field.
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spelling pubmed-54304912017-05-24 Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus() Bagnall, Neil H. Ruffell, Angela Raza, Ali Elliott, Timothy P. Lamb, Jane Hunt, Peter W. Kotze, Andrew C. Int J Parasitol Drugs Drug Resist Article Resistance to the anthelmintic drug monepantel (Zolvix(®)) has emerged in parasitic worms infecting sheep and goats. The mechanism of resistance in these cases is unknown. The drug targets nicotinic acetylcholine receptors belonging to the nematode-specific DEG-3 subfamily. We examined the receptor gene, Hco-mptl-1, in a highly Zolvix(®)-resistant and a -susceptible isolate of the parasitic nematode Haemonchus contortus. cDNA coding for the full length receptor protein (Hco-MPTL-1) was present in all clones prepared from a pool of susceptible larvae (21/21 clones) and approximately 50% of those from the resistant isolate (17/33). On the other hand, the remaining clones from the resistant isolate showed various mutations that resulted in truncated predicted proteins, missing at least one transmembrane domain. The most common mutation (11/33 clones) resulted in the retention of intron 15, a premature stop codon, and a truncated protein. Sequencing of intron 15 genomic DNA showed very few SNPs in susceptible larvae and in 12/18 clones from resistant larvae, alongside the presence of at least 17 SNPs in the remaining resistant clones. The present study shows that the highly resistant isolate has a number of mutations in the drug target gene that would most-likely result in a non-functional receptor, thus rendering the larvae insensitive to the drug. The presence of many wild-type sequences in this highly-resistant population suggests that there was a significant presence of heterozygotes in the survivors of the field drench treatment from which the isolate was derived, and hence that at least some of the mutations may be dominant. Alternatively, their presence may be due to the additional influence of mutations at another locus contributing to the resistance phenotype. The presence of multiple separate mutations in the Hco-mptl-1 gene in this viable field-derived worm isolate may at least partly explain why resistance to Zolvix(®) has arisen rapidly in the field. Elsevier 2017-05-04 /pmc/articles/PMC5430491/ /pubmed/28501715 http://dx.doi.org/10.1016/j.ijpddr.2017.05.001 Text en © 2017 The Authors http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Article
Bagnall, Neil H.
Ruffell, Angela
Raza, Ali
Elliott, Timothy P.
Lamb, Jane
Hunt, Peter W.
Kotze, Andrew C.
Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title_full Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title_fullStr Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title_full_unstemmed Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title_short Mutations in the Hco-mptl-1 gene in a field-derived monepantel-resistant isolate of Haemonchus contortus()
title_sort mutations in the hco-mptl-1 gene in a field-derived monepantel-resistant isolate of haemonchus contortus()
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5430491/
https://www.ncbi.nlm.nih.gov/pubmed/28501715
http://dx.doi.org/10.1016/j.ijpddr.2017.05.001
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