Candidate gene analysis of genetic resistance to gastrointestinal nematodes in sheep through association of single nucleotide polymorphism with phenotypic traits Selvam R.1,*, Murali N.2, Thiruvenkadan A.K.3, Ponnudurai G.4, Jawahar K. Thilak Pon5, Kathiravan P.6 1Department of Animal Genetics and Breeding, Veterinary College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Theni-625 534, Tamil Nadu, India 2Alambadi Cattle Breed Research Centre, Karimangalam, Dharmapuri-635 111, Tamil Nadu, India 3Department of Animal Genetics and Breeding, Veterinary College and Research Institute, Namakkal-637 002, Tamil Nadu, India 4Department of Veterinary Parasitology, Veterinary College and Research Institute, Namakkal-637 002, Tamil Nadu, India 5Livestock Farm Complex, Madhavaram Milk Colony, Chennai-600 051, Tamil Nadu, India 6Animal Production and Health Laboratory Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Vienna, Austria *Corresponding Author: R. Selvam, Department of Animal Genetics and Breeding, Veterinary College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Theni-625 534, Tamil Nadu, India, Email: selvam.r@tanuvas.ac.in
Online Published on 8 February, 2024. Abstract Background A study was executed to analyze the genetic resistance to gastrointestinal nematodes through the association of single nucleotide polymorphism markers in Toll-like receptor genes with phenotypic indicator traits in Kilakarsal and Vembur sheep breeds. Methods The phenotypic traits for analyzing the gastrointestinal nematode infection namely FEC, change in PCV and change in body weight were recorded. The SNP markers in TLR3, TLR5, TLR6, TLR9 and TLR10 genes were employed for genotyping. Competitive allele-specific PCR-based endpoint genotyping was used to type the SNPs. The gene and genotype frequencies were estimated by using the PEAS software program. A complete fixed effects model was utilized for analysis of the association of various genotypes at each SNP with phenotypic indicator traits. Result The global minor allele frequency of different polymorphic SNP loci ranged from 0.06 to 0.48 with a mean of 0.23, signifying their fitness for the association study. The effect of the farm had no significant influence on FEC and change in body weight, however, had a significant effect on change in PCV (P<0.05). No significant difference was detected between the sexes with FEC, change in PCV and change in body weight. The TT genotype in the TLR9_1769_CT locus showed the lowest least-squares mean FEC. The remaining 22 SNP loci showed no significant difference (P>0.05) with mean FEC. Association of 23 TLR SNP genotypes with change in PCV and change in body weight revealed no significant effect (P>0.05). Top Keywords Competitive allele-specific PCR, Gastrointestinal nematode, Genetic resistance, Single nucleotide polymorphism, TLR genes. Top |