Nucleotide sequence and polymorphism of MHC class II DQB exon 2 alleles in C hinese yakow ( B os grunniens × B os taurus )

Summary The objective of this study is to describe the gene characteristics of the bovine lymphocyte antigen ( B oLA)‐ DQB exon 2 locus in C hinese yakow ( B os grunniens  ×  B os taurus ) and to compare it with previously reported patterns in other bovidae species to investigate genetic factors for disease resistance. The exon 2 of the MHC class II DQB gene was cloned and sequenced. It was revealed by sequence analyses that there are 36 DQB exon 2 alleles among 44 C hinese yakow. These alleles exhibited a high degree of nucleotide and amino acid polymorphism with most amino acid variations occurring at positions forming the peptide‐binding sites ( PBS ). The DQB loci were analysed for patterns of synonymous ( d S ) and nonsynonymous ( d N ) substitution. The Chinese yakow was observed to be under strong positive selection in the DQB exon 2 peptide‐binding sites ( d N  = 0.147, P  <   0.01). It appears that this variability among C hinese yakow confers the ability to mount immune responses to a wide variety of peptides or pathogens.