Molecular analysis of HLA-B in the Malaysian aborigines

We have examined 56 unrelated individuals from Malaysian aborigines for their DNA polymorphism of the HLA-B gene by sequence specific oligonucleotide probe (SSO) method. Using the SSO hybridization, we found that one specific DNA allele with a B*1513 like pattern of epitope combination (ECB1513) was dominant among the Melayu Asli (Af = 41.9%) and the Senoi (Af = 24%). To determine the nucleotide sequences of ECB1513, a DNA fragment spanning from the beginning of exon 1 to the middle of exon 4 of the HLA-B gene was amplified by polymerase chain reaction (PCR) from two ECB1513 positive individuals, and the PCR products were cloned and sequenced. This sequencing analysis confirmed that ECB1513 was identical to HLA-B*1513 in exon 1, 2, 3, and 4. Amino acid sequence of this major allele, HLA-B*1513, in the aborigines especially around the peptide binding groove (B and F pockets), was compared with that of African B*5301 that had been suggested to confer resistance to malaria infection in Africa. The amino acid residues composing of the F pocket were completely identical in B*1513 and B*5301. These observations suggest that a common environmental factor, the malaria infection, might have independently enhanced the selection of functional change in the polymorphic portion of HLA-B gene in Africa and in South-East Asia.