Prosimian MHC-DQB allelic polymorphisms.

In this report the first description of MHC-DQB homologues in prosimians, the lemurs (Lemur fulvus sanfordi) and galagos (Galago garnetti and G. senegalensis moholi), is presented. In these species the class II alleles are similar to their human counterparts, in that the number and position of substitutions are analogous to the substitutions among various human DQB alleles. Presence of allelic variants for both DQB1 and DQB2 in all three species of prosimians studied suggests that the divergence of DQB1-DQB2 allelic lineages predates the divergence of human and prosimian lineages. The DQB2-like sequences from both species of the Galago seem more distant to human DQB2, and somewhat distant to that of the lemur DQB2 and bear numerous species-specific substitutions. It is not clear whether these DQB2-like alleles belong to a third DQB locus or are a true homologue of the contemporary HLA-DQB2 locus.