ALLELIC DIVERSITY AT THE MHC-DP LOCUS IN RHESUS MACAQUES (MACACA-MULATTA)

Allelic diversity at the major histocompatibility complex class II DP locus of rhesus macaques was studied by sequencing exon 2 of Mamu-DPA1 and -DPB1 genes. The Mamu-DPA1 gene is apparently invariant, whereas the Mamu-DPB1 locus displays polymorphism Here we report the character ization of 1 Mamu-DPA1 and 13 Mamu-DPB1 alleles which were compared wi th other available primate Mhc-DPA1 and -DPB1 sequences. As compared w ith Mhc-DRB and -DQB1, most codons for the contact residues in the ant igen binding site of the primate Mhc-DPB1 gene have a relatively low d egree of variation in encoding various types of amino acids. In contra st to Mhc-DRB and -DQB, the HLA- and Mamu-DPB1 sequences cluster in a species-specific manner in phylogenetic trees. Mhc-DPB1 polymorphisms, however, are inherited in a transspecies mode of evolution, as is dem onstrated by the sharing of lineage members between closely related ma caque species. The data demonstrate that the transspecies character of Mhc-DPB1 polymorphism was retained over much shorter periods of time as compared with its sister class II loci, Mhc-DQ and -DR.