Lack of association of resistance towards Haemonchus contortus infection with PCR-RFLP of MHC-DYA gene in Rambouillet crossbred sheep

The present study was carried out to find class I molecular marker for resistance and susceptibility against Haemonchus contortus infection in Rambouillet crossbred sheep. Random samples of blood and faeces (50) were collected from adult sheep maintained at Sheep Breeding Farm, Reasi, Jammu and Kashmir, India. Genomic DNA was isolated and a 719 bp fragment from exon IV-V of MHC-DYA was amplified using specific primers. The PCR product was digested with restriction enzyme Alu I and Taq I. Alu I digestion revealed only one type of banding pattern with 3 bands of size 386 bp, 323bp and 10 bp. Taq digestion of PCR product also revealed only one type of banding pattern with two bands of size 670 bp and 49 bp. Hence the exon IV-V of MHC-DYA gene was monomorphic for restriction enzyme Alu I and Taq I. Faecal egg count was done by modified McMaster's method following faecal larvae culture to identify the% of Haemonchus contortus. All the eggs counted were of strongyles out of which 90 +/- 5% (85-95%) of larvae were of Haemonchus contort us. Twenty one animals with epg of 0 were grouped as resistant. Nine animals were grouped as susceptible with epg of 400 and above. Since no polymorphism was detected, no association could be established.