In this report the first description of MHC-DQB homologues in prosimia
ns, the lemurs (Lemur fulvus sanfordi) and galagos (Galago garnetti an
d G. senegalensis moholi), is presented. In these species the class II
alleles are similar to their human counterparts, in that the number a
nd 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 hu
man 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 substitutio
ns. 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.