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 (DQA*0101) and -DQA2 (DQA*2001). 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 DQA*0101 and DQA*2001, 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.