Molecular cloning and sequence characterization of two genes, DQA1 and DQA2, from the Chinese yakow ( Bos grunniens × Bos taurus )

The major histocompatibility complex (MHC) plays a crucial role in the immune response to infectious diseases. The aimof the present study was to investigate the structural and functional characteristics and possible duplication of theMHC-DQAgenesin the Chinese yakow, which is well adapted to the Qinghai Tibetan Plateau. Two full-length cDNA sequences and partial 5 - and3 -untranslated regions (UTRs) were retrieved and denoted as Bogr×BoLA-DQA*0101 (DQA1) and Bogr×BoLA-DQA*2001 (DQA2),respectively. The percentage of nucleotide and amino acid sequences homology between Bogr×BoLA-DQA1 and Bogr×BoLA-DQA2showed that these two sequences have more identity to alleles of the correspondingDQA1andDQA2genes from other counterpartsthan to each other. Moreover, theBogr×BoLA-DQA1and-DQA2exhibited considerable variation with 99 nucleotide polymorphismsalong the length of the coding regions, leading to 52 amino acid polymorphisms. The phylogenetic tree investigation also demonstratedthat there is a larger genetic gap within these two identified genes than within orthologous genes from different animals, suggestingthat these sequences belong to nonallelic and duplicated types in the Chinese yakow. This is the first report to isolate and identify theMHC-DQA1and - DQA2genes. This result will deepen our understanding of MHC diversity among different ruminant species basedon comparative population genetics.

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