title: Identification and quantification of benzimidazole resistance polymorphisms in Haemonchus contortus isolated in Northeastern Brazil.
abstract: Haemonchus contortus is the most prevalent nematode in Brazil. The objective of this study was to select 6 populations of H. contortus of known or suspected benzimidazole resistance status and characterize these using quantitative real-time polymerase chain reaction (qPCR) for single nucleotide polymorphisms (SNPs) F200Y, F167Y and E198A in the β-tubulin isotype 1 gene. qPCR was performed using DNA from a pool of 10 adult male H. contortus from a single animal per farm. Faecal egg count reduction test (FECRT) and egg hatch test (EHT) were used to determine the resistance status. Samples were obtained from 6 farms located in 5 counties in the Ceará State: Tauá, Boa Viagem, Quixadá, Santa Quitéria and Solonópole. The inbred-susceptible-Edinburgh (ISE) isolate was used as reference for comparative purposes in the qPCR. Benzimidazole resistance was detected by FECRT on all farms with efficacy values ranging from 0 to 51%. EC50 values as determined by EHT were all above 1.49μg/ml. High frequencies of the resistant SNPs F200Y and F167Y alleles were detected but no resistance was detected at SNP E198A. Our results suggest that the SNPs F167Y and F200Y are both important for benzimidazole resistance in the studied populations.
authors.affiliation: Programa de Pós-graduação em Ciências Veterinárias/Universidade Estadual do Ceará, Faculdade de Veterinária, Universidade Estadual do Ceará, Av. Dedé Brasil, 1700, CEP 60714-903 Fortaleza, CE, Brazil.
authors.forename: Jessica Maria Leite
authors.initials: JM
authors.lastname: dos Santos
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária - Caprinos e Ovinos, Estrada Sobral/Groaíras, km 04, Caixa Postal 145, CEP 62010-970 Sobral, CE, Brazil.
authors.forename: Jomar Patrício
authors.initials: JP
authors.lastname: Monteiro
authors.affiliation: Programa de Pós-graduação em Ciências Veterinárias/Universidade Estadual do Ceará, Faculdade de Veterinária, Universidade Estadual do Ceará, Av. Dedé Brasil, 1700, CEP 60714-903 Fortaleza, CE, Brazil.
authors.forename: Wesley Lyeverton Correia
authors.initials: WL
authors.lastname: Ribeiro
authors.affiliation: Programa de Pós-graduação em Ciências Veterinárias/Universidade Estadual do Ceará, Faculdade de Veterinária, Universidade Estadual do Ceará, Av. Dedé Brasil, 1700, CEP 60714-903 Fortaleza, CE, Brazil.
authors.forename: Iara Tersia Freitas
authors.initials: IT
authors.lastname: Macedo
authors.affiliation: Programa de Pós-graduação em Ciências Veterinárias/Universidade Estadual do Ceará, Faculdade de Veterinária, Universidade Estadual do Ceará, Av. Dedé Brasil, 1700, CEP 60714-903 Fortaleza, CE, Brazil.
authors.forename: Ana Lourdes Fernandes
authors.initials: AL
authors.lastname: Camurça-Vasconcelos
authors.affiliation: Empresa Brasileira de Pesquisa Agropecuária - Caprinos e Ovinos, Estrada Sobral/Groaíras, km 04, Caixa Postal 145, CEP 62010-970 Sobral, CE, Brazil.
authors.forename: Luiz da Silva
authors.initials: Lda S
authors.lastname: Vieira
authors.affiliation: Programa de Pós-graduação em Ciências Veterinárias/Universidade Estadual do Ceará, Faculdade de Veterinária, Universidade Estadual do Ceará, Av. Dedé Brasil, 1700, CEP 60714-903 Fortaleza, CE, Brazil. Electronic address: claudia.bevilaqua@pq.cnpq.br.
authors.forename: Claudia Maria Leal
authors.initials: CM
authors.lastname: Bevilaqua
mesh_terms: D000483:Alleles; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology*; D001938:Brazil; D004351:Drug Resistance / Q000235:genetics*; D005243:Feces / Q000469:parasitology; D006188:Haemonchiasis / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000187:drug effects / Q000235:genetics; D020128:Inhibitory Concentration 50; D008297:Male; D010270:Parasite Egg Count; D020641:Polymorphism, Single Nucleotide; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology*; D014404:Tubulin / Q000235:genetics*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D014404:Tubulin; C031000:benzimidazole
keywords: Haemonchus contortus; Quantitative real-time PCR; SNP; Sheep; β-Tubulin gene