Isolation of two cDNAs encoding MHC-DQA1 and -DQA2 from the water buffalo, Bubalus bubalis.

In the present study, we explored structural and functional variations and possible duplication of the major histocompatibility complex (MHC)-DQA gene in water buffalo (Bubalus bubalis). Two cDNA sequences, amplified from one individual water buffalo, were designated as Bubu-DQA1 (DQA0101) and -DQA2 (DQA2001). The percentage of nucleotide and amino acid similarity between Bubu-DQA1 and -DQA2 revealed that these sequences display more similarity to alleles of respective DQA1 and DQA2 genes from other ruminant species than to each other. The phylogenetic analysis also revealed a considerably larger genetic distance between these two genes than between homologous genes from other species. The larger genetic distance between DQA0101 and DQA2001, and the presence of different bovine DQA putative locus specific amino acid motifs, suggests these sequences are non-allelic. This finding is consistent with DQA gene duplication in other ruminants.