Contrasting patterns of isotype-1 β-tubulin allelic diversity in Haemonchus contortus and Haemonchus placei in the southern USA are consistent with a model of localised emergence of benzimidazole resistance

Chaudhry, Umer, Redman, E.M., Kaplan, Ray, Yazwinski, Thomas, Sargison, Neil and Gilleard, John S. (2020) Contrasting patterns of isotype-1 β-tubulin allelic diversity in Haemonchus contortus and Haemonchus placei in the southern USA are consistent with a model of localised emergence of benzimidazole resistance VETERINARY PARASITOLOGY, 286, 109240.

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Abstract

The benzimidazoles are one of the most important broad-spectrum anthelmintic drug classes for parasitic nematode control in domestic animals and humans. They have been widely used in livestock, particularly in small ruminants for over 40 years. This has resulted in widespread resistance in small ruminant gastrointestinal nematode parasite species, especially Haemonchus contortus. Benzimidazole resistance mutations have also been reported in Haemonchus placei, but only at low frequencies, suggesting resistance is at a much earlier stage of emergence than is the case for H. contortus. Here, we investigate the haplotype diversity of isotype-1 β-tubulin benzimidazole resistance mutations and the population genetic structure of H. contortus and H. placei populations from sheep and cattle from the southern USA. Microsatellite genotyping revealed a low level of genetic differentiation in six H.placei and seven H. contortus populations examined. This is consistent with several previous studies from other regions, mainly in H. contortus, supporting a model of high gene flow between parasite populations. There was a single F200Y(TAC) haplotype present in all six H. placei populations across Georgia, Florida and Arkansas. In contrast, there were at least two different F200Y(TAC) haplotypes (up to four) and two different F167Y(TAC) haplotypes across the seven H. contortus populations studied. These results provide further evidence to support a model for benzimidazole resistance in Haemonchus spp, in which resistance mutations arise from a single, or the small number of locations, in a region during the early phases of emergence, and subsequently spread due to animal movement.

Item Type:	Article
Divisions :	Faculty of Health and Medical Sciences > School of Veterinary Medicine
Authors :	Name Email ORCID Chaudhry, Umer u.chaudhry@surrey.ac.uk Redman, E.M. Kaplan, Ray Yazwinski, Thomas Sargison, Neil Gilleard, John S.
Date :	October 2020
DOI :	10.1016/j.vetpar.2020.109240
Copyright Disclaimer :	© 2020 Elsevier B.V. All rights reserved.
Uncontrolled Keywords :	Haemonchus contortus; Haemonchus placei; Benzimidazole resistance; Isotype-1 β -tubulin; Resistance emergence and spread
Depositing User :	Diane Maxfield
Date Deposited :	05 Oct 2020 15:43
Last Modified :	05 Oct 2020 15:43
URI:	http://epubs.surrey.ac.uk/id/eprint/858658

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