Molecular detection of benzimidazole resistance in Haemonchus contortus of sheep in Punjab

Abstract

Single nucleotide polymorphism (SNP) at codon 167, 198 and 200 of β-tubulin isotype 1 gene accounts for benzimidazole resistance in Haemonchus contortus. To assess the anthelmintic resistance to benzimidazole group, allele specific polymerase chain reaction (AS-PCR) was employed on 50 adults of local abattoir of Ludhiana and 138 harvested larvae of H. contortus from faecal samples collected from field flocks of 6 districts of western zone of Punjab. The adults were found to be homozygous resistant (rr) showing 100% prevalence of resistant allele (r). AS-PCR on 138 larvae collected from different districts of Punjab showed 49.28% (69) homozygous resistant (rr), 3.62% (5) homozygous susceptible (SS) and 46.37% (64) heterozygous (rS) population. Species was confirmed as H. contortus by PCR-RFLP from the three fragments of size 462 bp, 211 bp and 147 bp. The pioneer study on the molecular diagnosis of benzimidazole resistance in H. contortus showed an overall allele frequency for resistant and susceptible population to be 0.72 (TTC) and 0.28 (TAC), espectively indicating development of high level of resistance in sheep.

Targeting the nervous system of the parasitic worm, Haemonchus contortus with quercetin

“…Anthelminthic resistance is now a widespread problem, especially in H. contortus, due to its enormous genetic diversity, which possibly is allowing the anthelminthic resistance alleles to be rapidly selected 26,27 . Other studies showed the mechanism of benzimidazole resistance due to point mutations in the β-tubulin gene, the target site of the drug [28][29][30][31] . In vitro development of resistance in H. contortus against thiabendazole also highlighted the signi cance of a point mutation (from glutamate to alanine) at codon 198 of the β-tubulin gene, expressed in vivo relevance 32 .…”