Mohanraj Karthik, Subhadra Subhra, Kalyanasundaram Aravindan, Ilangopathy Manikkavasagan, Raman Muthusamy
Department of Veterinary Parasitology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University, Chennai, Tamil Nadu 600 007 India.
J Parasit Dis. 2017 Mar;41(1):282-288. doi: 10.1007/s12639-016-0793-2. Epub 2016 Jun 20.
Extensive and indiscriminate use of the benzimidazole class of drugs has led to the onset of anthelmintic resistance. In tropical countries like India, is the most pathogenic parasite infecting sheep and goats. The widespread presence of resistant helminths (especially ) threatens the livestock farming. The use of various drugs has led to single nucleotide polymorphism that causes specific amino acid substitutions in β-tubulin protein of to confer resistance. This emphasizes the need for a survey on the present status of resistance in India. In this study, allele specific PCR was employed to screen the presence of a SNP, a thymine-to-adenine transversion which leads to substitution of amino acid in codon 200 of β-tubulin gene that is correlated specifically with BZ resistance. Third stage larvae (L3) from pooled faecal cultures of four organized sheep farms served as a source of genomic DNA for identification of and further genotype analysis. A total of 1000 larvae was screened, out of which 673 larvae were identified as . Among 673 larvae, 539 larvae (80 %) were genotyped as homozygous resistant (rr) and remaining 134 (20 %) were heterozygous susceptible (Sr) by allele specific PCR. The concluded resistance status reasons out the failure of anthelmintic drug in treating ruminants. Immediate steps are needed to avoid further aggravation of the problem. Target selective treatment by reviewing the resistance status of individual drugs, appropriate use of anthelmintic drugs and other control strategies will provide a pragmatic option for delaying the further spread of anthelmintic resistance.
苯并咪唑类药物的广泛和无差别使用已导致抗蠕虫药耐药性的出现。在印度等热带国家，是感染绵羊和山羊的最具致病性的寄生虫。耐药蠕虫（尤其是）的广泛存在威胁着畜牧业。各种药物的使用导致了单核苷酸多态性，从而在的β-微管蛋白中引起特定氨基酸替换，赋予耐药性。这凸显了对印度耐药现状进行调查的必要性。在本研究中，采用等位基因特异性PCR来筛选一个单核苷酸多态性（SNP）的存在，即胸腺嘧啶到腺嘌呤的颠换，这导致β-微管蛋白基因第200密码子中的氨基酸替换，该替换与苯并咪唑耐药性具有特异性关联。来自四个规模化养羊场粪便混合培养物的第三期幼虫（L3）作为基因组DNA的来源，用于鉴定并进一步进行基因型分析。总共筛选了1000只幼虫，其中673只幼虫被鉴定为。在673只幼虫中，通过等位基因特异性PCR，539只幼虫（80%）被基因分型为纯合抗性（rr），其余134只（20%）为杂合敏感（Sr）。得出的耐药状况解释了抗蠕虫药治疗反刍动物失败的原因。需要立即采取措施避免问题进一步恶化。通过审查个别药物的耐药状况进行目标选择性治疗、合理使用抗蠕虫药和其他控制策略，将为延缓抗蠕虫药耐药性的进一步传播提供一个切实可行的选择。
