title: Diagnosis of resistance alleles in codon 167 of the beta-tubulin (Cya-tbb-1) gene from third-stage larvae of horse cyathostomins.
abstract: Anthelmintic resistance is a serious problem for the control of equine gastrointestinal nematodes. In the present survey, 173 third stage larvae of cyathostomins were investigated from three different locations for the presence of the resistant genotype at codon 167 of the beta-tubulin gene, as this is the most prevalent mutation. The larvae from the state of Parana (n=67), Sao Paulo (n=54) and Santa Catarina (n=52), showed 61.2; 31.5 and 38.5% of the heterozygous resistant genotype - TTC/TAC, respectively. An unpublished mutation at codon 172 that results in a serine (S) to threonine (T) substitution was found in 17.9% (12/67) of samples from Parana; and 13.0% (7/54) of samples from Sao Paulo. We have compared the molecular diagnostic with the fecal egg count data (R2=-0.79) from the same farms, and consider that the use of routine molecular diagnostic in individual larva may help to determine the population genetic distribution that is associated with drug failure.
authors.affiliation: Department of Veterinary Medicine, Laboratory of Parasitic Diseases, Federal University of Parana, R: dos Funcionarios 1540, Curitiba PR. CEP: 80035-050, Brazil.
authors.forename: Juliana Bana
authors.initials: JB
authors.lastname: Ishii
authors.affiliation: Department of Morphophysiology, University of Camaguey, Circunvalación Norte, Km 5 1/2, 74650 Camaguey, Cuba.
authors.forename: Amilcar
authors.initials: A
authors.lastname: Arenal
authors.affiliation: Department of Veterinary Medicine, Laboratory of Parasitic Diseases, Federal University of Parana, R: dos Funcionarios 1540, Curitiba PR. CEP: 80035-050, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Felix
authors.affiliation: Department of Veterinary Medicine, Laboratory of Parasitic Diseases, Federal University of Parana, R: dos Funcionarios 1540, Curitiba PR. CEP: 80035-050, Brazil.
authors.forename: Ursula
authors.initials: U
authors.lastname: Yoshitani
authors.affiliation: Institute of Parasitology, McGill University, 21.111 Lakeshore Rd, Sainte-Anne de Bellevue, Canada.
authors.forename: Robin
authors.initials: R
authors.lastname: Beech
authors.affiliation: Department of Veterinary Medicine, Laboratory of Parasitic Diseases, Federal University of Parana, R: dos Funcionarios 1540, Curitiba PR. CEP: 80035-050, Brazil; National Institute of Science and Technology, INCT-Livestock. Av., Antonio Carlos 6627, Belo Horizonte MG. CEP: 31270-901, Brazil. Electronic address: molento@ufpr.br.
authors.forename: Marcelo Beltrão
authors.initials: MB
authors.lastname: Molento
mesh_terms: D000483:Alleles; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D003062:Codon; D018509:DNA, Helminth / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics*; D005243:Feces / Q000469:parasitology; D005838:Genotype; D006734:Horse Diseases / Q000469:parasitology; D006736:Horses; D007814:Larva / Q000187:drug effects; D010270:Parasite Egg Count / Q000662:veterinary; D017183:Strongylida / Q000187:drug effects* / Q000235:genetics*; D014404:Tubulin
chemical_list: D000871:Anthelmintics; D003062:Codon; D018509:DNA, Helminth; D014404:Tubulin
keywords: Benzimidazole; Equine; Parasite control; Small strongyles