The objective of this study was to assess the genetic diversity of the Sirohi goat for and loci, and to study their association with antibody response induced by the Peste des petits ruminants (PPR) vaccine. A total of 360 Sirohi kids were studied using single stranded confirmation polymorphism (SSCP) followed by polymerase chain reaction sequence-based typing (PCR-SBT) for and diversities. The competitive enzyme-linked immuno-sorbent assay (C-ELISA) was used to evaluate immune response post-PPR vaccination. Study revealed rich diversity of major histocompatibility complex (MHC) region in goat. A total of 18 and 15 alleles were obtained which were new. Alleles DRB*0104 and DQB1*0101 were the most common. The approach of SSCP combined with PCR-SBT reflects cost-effective and most powerful approach to decipher the genetic diversity in complex MHC region. Study revealed variation in and genes in Sirohi flock along with high Wu-Kabat index. A total of 16 of the 89 amino acid residue sites in and 19 of 86 residue sites in had more than three amino acid substitutions. Positive evolutionary selection was evident in Sirohi for MHC region. Nonsignificant association of and genotypes with PPR virus (PPRV) vaccine response revealed complexity of the phenotype and importance of other factors for vaccine response. Rich diversity of and genes reflects the fitness of the population and importance of this locus for future selection programmes.

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India harbors a vast diversity of sheep (40 breeds). The study was carried out to assess the genetic diversity of DRB1 and DQA2 locus of the ovar-MHC and their possible association with Peste des petits ruminants (PPR) virus vaccine response in Malpura and Avikalin sheep breeds maintained at an organized institute flock in the semi-arid region of India. Genetic analysis revealed the rich diversity of DRB1 locus with 23 alleles in Malpura and 21 alleles in Avikalin sheep that included 9 new alleles. DQA2 locus also had rich diversity with 19 alleles in Malpura and 20 alleles in Avikalin sheep that included 7 new alleles. At the protein level, high variability alike at the nucleotide level was observed. A marker for footrot susceptibility, DQA2*1101 was absent in both breeds. Genotypic association of DRB1 and DQA2 with PPR vaccine response was statistically non-significant. Vaccine response being a multifactorial (polygenic and influenced by environment) variable, could not show statistically significant association with MHC genotypes in the present study. However, rich genetic diversity of DRB1 and DQA2 gene reflects the importance of this locus for future selection programs.

Enterotoxaemia (ET) is a fatal enteric disease of small ruminants attributable to a toxigenic type of Clostridium perfringens. The key strategy for prevention of ET is the management and vaccination. Present study aimed at identifying the sources of variation for ET vaccine response especially against epsilon toxin in 173 sheep that included 83 Avikalin and 90 Malpura lambs raised at the institute flock in the semi-arid region of India. The mean age at vaccination was 90 days. Sera were tested by blocking ELISA. Study showed significant variability for response to ET vaccine. 5.2% animals had + positivity, 20.8% animals had ++ positivity, 51.4% animals had +++ positivity and 22.5% animals had ++++ positivity. Amongst environmental determinants, breed, season, sex and age at vaccination proved to be non-significant sources of variation (P > 0.05). MHC genotypes with DRB1 gene and DQA2 genes also revealed non-significant association with ET vaccine response; however, a trend of decreasing PI values with increasing ranks was observed. Study revealed strong response of epsilon toxin along with complexity of the ET vaccine response as phenotype to be explained by genetic and non-genetic factors. The importance of better management practices and vaccination is suggested for preventive measures.

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