Detection of benzimidazole resistance in Haemonchus contortus populations collected from sheep of Uttarakhand using allele specific PCR assay

Abstract

Allele specific PCR (AS-PCR) was standardized to detect genotypic and allelic frequencies of Haemonchus contortus
worm populations of 2 agro-climatic regions viz. Tarai and Hill regions of Uttarakhand. Genotyping of H. contortus
worms revealed that overall frequency of homozygous susceptible worms were significantly higher (0.61) than
homozygous resistant (0.17) worms. Within Tarai region, the frequency of homozygous resistant worms were significantly
higher (0.48) in Pantnagar than homozygous susceptible (0.20) worms whereas, significantly higher frequency of
homozygous susceptible worms were found in Haldwani (0.52) and Tanakpur (0.80). In Hills, the frequency of
homozygous susceptible worms was significantly higher than homozygous resistant worms collected from Nainital
(0.72 and 0.08 respectively) and Almora (0.84 and 0.04 respectively).
Overall, the frequency of susceptible allele was significantly higher (0.72) than resistant allele (0.28). In Tarai
region, frequency of resistant allele (0.36) was significantly lower than susceptible allele (0.64). The frequency of
resistant allele was significantly higher in Pantnagar (0.64) whereas significantly higher frequency of susceptible allele
was recorded in H. contortus collected from Haldwani (0.68) and Tanakpur (0.86). In Hill region, frequency of resistant
allele (0.14) was significantly lower than susceptible allele (0.86).