title: The presence of benzimidazole resistance mutations in Haemonchus placei from US cattle.
abstract: Haemonchus populations were collected from cattle from mid-western and eastern Southern US (four and six populations, respectively) to determine the relative prevalence of Haemonchus contortus and Haemonchus placei and the frequency of the three isotype-1 β-tubulin polymorphisms associated with benzimidazole resistance. A minimum of 32 individual adult worms were genotyped at position 24 of the rDNA ITS-2 for each population to determine species identity (296 worms in total). One population from Georgia was identified as 100% H. contortus with the remaining nine populations identified as 100% H. placei. For the H. contortus population, 29 out of 32 worms carried the P200Y (TAC) isotype-1 β-tubulin and 2 out of 32 worms carried the P167Y (TAC) benzimidazole resistance associated polymorphisms respectively. For H. placei, six out of the nine populations contained the P200Y (TAC) isotype-1 β-tubulin benzimidazole resistance associated polymorphism at low frequency (between 1.6% and 9.4%) with no resistance associated polymorphisms being identified at the P198 and P167 codons. This is the first report of the P200Y (TAC) isotype-1 β-tubulin benzimidazole resistance associated polymorphism in H. placei. The presence of this mutation in multiple independent H. placei populations indicates the risk of resistance emerging in this parasite should benzimidazoles be intensively used for parasite control in US cattle.
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada.
authors.forename: Umer
authors.initials: U
authors.lastname: Chaudhry
authors.affiliation: Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Miller
authors.affiliation: Department of Animal Science, University of Arkansas, Fayetteville, AR, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Yazwinski
authors.affiliation: Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
authors.forename: Ray
authors.initials: R
authors.lastname: Kaplan
authors.affiliation: Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada. Electronic address: jsgillea@ucalgary.ca.
authors.forename: John
authors.initials: J
authors.lastname: Gilleard
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D005838:Genotype; D005845:Georgia; D006188:Haemonchiasis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000235:genetics* / Q000302:isolation & purification; D008297:Male; D009154:Mutation; D017422:Sequence Analysis, DNA / Q000662:veterinary; D014404:Tubulin / Q000235:genetics
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D018509:DNA, Helminth; D021903:DNA, Ribosomal Spacer; D014404:Tubulin; C031000:benzimidazole
keywords: Anthelmintic resistance; Benzimidazoles; Cattle parasites; Haemonchus contortus; Haemonchus placei