Chaudhry Umer, Miller Melissa, Yazwinski Thomas, Kaplan Ray, Gilleard John
Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada.
Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
Vet Parasitol. 2014 Aug 29;204(3-4):411-5. doi: 10.1016/j.vetpar.2014.05.025. Epub 2014 May 23.
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.
从美国南部中西部和东部的牛身上采集血矛线虫种群（分别为4个和6个种群），以确定捻转血矛线虫和长刺血矛线虫的相对流行率，以及与苯并咪唑抗性相关的三种1型β-微管蛋白多态性的频率。每个种群至少对32条成年虫的核糖体DNA ITS-2的第24位进行基因分型，以确定物种身份（总共296条虫）。来自佐治亚州的一个种群被鉴定为100%捻转血矛线虫，其余9个种群被鉴定为100%长刺血矛线虫。对于捻转血矛线虫种群，32条虫中有29条携带P200Y（TAC）1型β-微管蛋白，32条虫中有2条分别携带与苯并咪唑抗性相关的P167Y（TAC）多态性。对于长刺血矛线虫，9个种群中有6个种群低频（1.6%至9.4%）含有与苯并咪唑抗性相关的P200Y（TAC）1型β-微管蛋白多态性，在P198和P167密码子处未鉴定出与抗性相关的多态性。这是长刺血矛线虫中P200Y（TAC）1型β-微管蛋白苯并咪唑抗性相关多态性的首次报道。多个独立的长刺血矛线虫种群中存在这种突变，表明如果在美国牛的寄生虫控制中大量使用苯并咪唑，这种寄生虫出现抗性的风险。
