Resistance to benzimidazole (BZ) anthelmintics is common in ovine nematodes of economic importance. Single nucleotide polymorphisms (SNP) at three positions in the isotype 1 β- tubulin gene have been associated with BZ resistance and molecular tests for the detection of BZ resistance have been developed. In order to determine if such tests are practicable in Ireland the polymorphisms associated with BZ resistance must be identified. To this end, BZ-resistant nematodes were recovered from four farms in Ireland. Resistant Teladorsagia circumcincta, Cooperia curticei and Trichostrongylus colubriformis were recovered, with resistant T. circumcincta the most common and the only species studied further. Sequencing of the isotype 1 β-tubulin gene from resistant T. circumcincta identified a T - A transition, resulting in an F200Y substitution known to be responsible for BZ-resistance, on three of the farms. However, on the fourth farm the frequency of the resistant A allele was only 0.33 indicating another BZ resistance mechanism may be present on this farm. An additional polymorphism resulting in a substitution of glutamate for leucine (E198L) was also found on this farm at low frequency (0.17). No polymorphisms at position 167 were identified on any farm. Therefore, molecular tests to detect BZ resistance in T. circumcincta in Ireland could prove useful; however, they may result in some instances of resistance remaining undetected.

中文翻译：

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爱尔兰Teladorsagia circumcincta苯并咪唑抗药性的遗传基础。

对苯并咪唑（BZ）驱虫药的抗性在具有经济重要性的绵羊线虫中很常见。同种型1β-微管蛋白基因中三个位置的单核苷酸多态性（SNP）已与BZ抗性相关，并且已经开发了用于检测BZ抗性的分子测试。为了确定这种测试在爱尔兰是否可行，必须确定与BZ抗性相关的多态性。为此，从爱尔兰的四个农场回收了抗BZ的线虫。回收了抗性圆角拟南芥（Teladorsagia circumcincta），库珀（Cooperia curticei）和粘毛毛滴虫（Trichostrongylus colubriformis），其中最常见的环丁形衣原体（T. circumcincta）也是唯​​一需要进一步研究的物种。从抗药性圆环线虫的同种型1β-微管蛋白基因的测序确定了T-A过渡，导致在三个农场中导致对BZ抗性负责的F200Y替代品。但是，在第四个农场中，抗性A等位基因的频率仅为0.33，这表明该农场中可能存在另一种BZ抗性机制。该农场还以较低的频率（0.17）发现了另一种多态性，导致谷氨酸替代亮氨酸（E198L）。在任何农场中均未发现167位的多态性。因此，在爱尔兰进行的用于检测T.circumcincta中BZ耐药性的分子检测可能是有用的。但是，它们可能导致在某些情况下仍无法检测到电阻。该农场还以较低的频率（0.17）发现了另一种多态性，导致谷氨酸替代亮氨酸（E198L）。在任何农场中均未发现167位的多态性。因此，在爱尔兰进行的用于检测T.circumcincta中BZ耐药性的分子检测可能是有用的。但是，它们可能导致在某些情况下仍无法检测到电阻。该农场还以较低的频率（0.17）发现了另一种多态性，导致谷氨酸替代亮氨酸（E198L）。在任何农场中均未发现167位的多态性。因此，在爱尔兰进行的用于检测T.circumcincta中BZ耐药性的分子检测可能是有用的。但是，它们可能导致在某些情况下仍无法检测到电阻。