Extensive genetic diversity in the HLA class II region of Africans, with a focally predominant allele, DRB1*1304.

Abstract

Molecular HLA class II typing of >1700 individuals from The Gambia in West Africa and Malawi in South-Central Africa revealed a striking diversity of HLA DRB-DQB haplotypes as defined by restriction fragment length polymorphism (RFLP); this diversity is twice as extensive as that found in northern Europeans. Despite this diversity, sequence and PCR/oligonucleotide analysis showed that the recently described variant DRBI*1304 is the commonest DRBI allele in The Gambia. The sequence, geographical distribution, and RFLP association of this allele, together with homozygosity test results, suggest that DRBI*1304 may have arisen from DRBI*1102 and have reached its remarkably high frequency as a result of recent directional selection. The prevalence of this unusual allele has implications for trials of subunit vaccines in this area. The extensive and distinctive HLA class II region polymorphism in sub-Saharan Africans is consistent with evidence from other genetic loci implying an African origin of modern Homo sapiens.

Induction of T Helper Type 1 and 2 Responses to 19-Kilodalton Merozoite Surface Protein 1 in Vaccinated Healthy Volunteers and Adults Naturally Exposed to Malaria

“…Novel T-cell epitopes identified in vaccinated American volunteers may not be relevant to populations where malaria is endemic (14). It was important to determine whether T-cell epitopes induced by the vaccine were also presented during natural malaria infection in endemic populations.…”

“…Both 3D7 and FVO strains of the recombinant MSP-1 19 antigen could induce cross-reactive T-cell responses. Immunity induced in naive volunteers may not be relevant to populations in areas where malaria is endemic (14). IFN-␥ responses to merozoite antigens are associated with resistance to malaria reinfection (18); therefore these were also evaluated in African donors in The Gambia in west Africa and Kenya in east Africa.…”

Causes of false-positive HIV rapid diagnostic test results

“…Hill et al [55] reported extensive HLA class II DR-DQ polymorphism in The Gambia and Malawi and, citing other reports, stated that Africans have a greater HLA diversity and more class II haplotypes than Caucasians, Asians, Indians and Pacific Islanders. Extensive HLA class 1 polymorphism has also been reported in Africans [56].…”

The ABCs of MHC

“…This scenario has been proposed to explain the finding of novel HLA-B alleles in South American native populations. 35 Novel HLA-DRB alleles have also been reported in West Africa, 36 Australia, 37 and Oceania. 38 In these populations, the novel alleles can be attributed to parasite-mediated selection for new peptide binding potential for specific parasites or diseases.…”