Abstract The study was done to determine the benzimidazole resistance-associated polymorphisms in seven organized goat farms in northern, central and southern regions of Kerala in south India. Results of Fecal Egg Count Reduction Test (FECRT) indicated benzimidazole resistance in all the farms with per cent reduction in fecal egg counts ranging from 16 to 94 per cent. A total of 250 Haemonchus contortus larvae were genotyped at codons 167, 198 and 200 of isotype 1 β-tubulin gene by PCR-RFLP. A 451 bp region of isotype 1 β-tubulin gene amplified by semi-nested PCR was subsequently digested with restriction enzymes Eco1051 (SnaBI), HpyCH4V and HpyCH4III for identification of SNPs at codons 167, 198 and 200, respectively. The results of genotyping revealed E198A polymorphism (GAA to GCA, glutamate to alanine at codon 198) with an overall frequency of 0.516 while no polymorphism was detected at codons 167 and 200. The high prevalence of E198A polymorphism and the absence of F200Y polymorphism in H. contortus populations in organized goat farms in Kerala might be attributed to the prolonged and intensive use of benzimidazoles resulting in high selection pressure for benzimidazole resistance mutations.

中文翻译：

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在印度南部喀拉拉邦有组织的山羊农场中，捻转血矛线虫种群的同种型 1 β-微管蛋白基因中 E198A 多态性的高流行率

摘要 本研究旨在确定印度南部喀拉拉邦北部、中部和南部地区七个有组织的山羊养殖场中苯并咪唑抗性相关的多态性。粪便鸡蛋计数减少试验 (FECRT) 的结果表明，所有农场都对苯并咪唑产生抗药性，粪便鸡蛋数量减少了 16% 至 94%。通过PCR-RFLP，总共250只Haemonchus contortus幼虫在167、198和200的同种型β-微管蛋白基因的密码子上进行了基因分型。通过半巢式 PCR 扩增的同种型 1 β-微管蛋白基因的 451 bp 区域随后用限制酶 Eco1051 (SnaBI)、HpyCH4V 和 HpyCH4III 消化，用于分别鉴定密码子 167、198 和 200 处的 SNP。基因分型结果显示 E198A 多态性（GAA 到 GCA，