African links and hepatitis B virus genotypes in the Republic of Yemen.

Hepatitis B virus (HBV) genotypes in three different communities in the Republic of Yemen with and without significant African links were studied. The subjects included indigenous Yemeni blood donors (n = 987), Africans who had settled down in Yemen for several generations (n = 97) and Soqotrans living on an island in the Indian Ocean close to the African coast (n = 99). Phylogenetic analysis of HBV surface region sequences showed the presence of two major genotypes; A and D: sequences from the blood donors were all genotype D (17/17); those from Africans residing in Yemen were predominantly genotype D (7/8) although one sequence was genotype A; whereas a mixture of genotype A and D was found among the Soqotrans (5/8 and 3/8 respectively). Genotype A sequences were associated with higher viral load, but the difference was not statistically significant. Human migration and international travel, may lead to an interaction between HBV genotypes. The Republic of Yemen is at a location where genotypes A and D meet. The results from this study suggest that genotype A is found only in communities with continuing African links and that genotype D remains the dominant genotype in settled populations. More studies are needed to examine possible long-term changes in HBV genotypes in this region.