The chimpanzee major histocompatibility complex class II DR subregion contains an unexpectedly high number of beta-chain genes

Abstract

The major histocompatibility complex (MHC) class II DR subregion of the chimpanzee was studied by restriction fragment length polymorphism (RFLP) analysis. Genomic DNA obtained from a panel of 94 chimpanzees was digested with the restriction enzyme Taq I and hybridized with an HLA-DR beta probe specific for the 3' untranslated (UT) region. Such a screening revealed the existence of 14 distinct DRB/Taq I gene-associated fragments allowing the definition of 11 haplotypes. Segregation studies proved that the number of chimpanzee class II DRB/Taq I fragments is not constant and varies from three to six depending on the haplotype. Comparison of these data with a human reference panel manifested that some MHC DRB/Taq I fragments are shared by man and chimpanzee. Moreover, the number of HLA-DRB/Taq I gene-associated fragments detected in a panel of homozygous typing cells varies from one to three and corresponds with the number of HLA-DRB genes present for most haplotypes. However, a discrepancy is observed for the HLA-DR4, -DR7, and -DR9 haplotypes since a fourth HLA-DRB pseudogene present within these haplotypes lacks its 3' UT region and thus is not detected with the probe used. These results suggest that chimpanzees have a higher maximum number of DRB genes per haplotype than man. As a consequence, some chimpanzee haplotypes must show a dissimilar organization of the MHC DR subregion compared to their human equivalents. The implications of these findings are discussed in the context of the trans-species theory of MHC polymorphism.

Polymorphism of C4 and CYP21 genes in various primate species

“…5~ SSPE at 65°C. Partial digests of DNA were not observed under the conditions described above as has been demonstrated by family segregation studies (34,35 and data not shown).…”

Major histocompatibility complex class II haplotypes in a breeding colony of chimpanzees (Pan troglodytes)

“…This particular combination was selected since, within a panel of human homozygous typing cells, the number of fragments detected corresponds with the number of HLA-DRB genes present per haplotype. In chimpanzees, this probe/enzyme combination defines at least 11 types of Purr-DR regions characterized by unique combinations of Taq I fragments (24). The distinct RFLP-defined Patr- (25).…”

Major hstocompatibility haplotypes in a breeding colony of chimpanzees (Pan troglodytes)

“…The existence of the equivalent of the HLA-DRB2 gene was documented for Hugo, a member of our chimpanzee population (26) 58 which is homozygous for its DR region (24). Hugo's haplotypes in question share the same RFLP profile with one of the haplotypes of chimpanzee Frits (24). Sequence analysis of the Frits bl haplotype allowed the detection of four alleles; Patr-DRBI *020I, -DRB3*020I, -DRB6*OlOS and -DRB5*0301 (Table 1) that also have been found for chimpanzee Hugo (1 1, 25,27).…”

“…). The last two columns show the RFLPdetermined OR specificities and their Corresponding number of fragments(24).The table does not show that all chimpanzees possessMhc-WA2 and -WE2 genes. The Mhc class II gene content of chimpanzee Hugo haplotype (Frits) has been determined by con$ mapping(26) whereas all others are deduced.…”