Exceptional genetic variability of hepatitis B virus indicates that Rwanda is east of an emerging African genotype E/A1 divide

In Western Africa, hepatitis B virus (HBV) genotype E predominates throughout a vast crescent spanning from Senegal to Namibia and at least to the Central African Republic to the East. Although from most of the eastern parts of sub-Saharan Africa only limited sets of strains have been characterized, these belong predominantly to genotype A. To study how far the genotype E crescent extends to the East, a larger number of HBV strains from Rwanda were analyzed. Phylogenetic analysis of 45 S fragment sequences revealed strains of genotypes A (n = 30), D (n = 10), C (n = 4), and B (n = 1). Twelve genotype A sequences formed a new cluster clearly separated from the reference strains of the known sub-genotypes. Thus, with four genotypes and at least six sub-genotypes and a new cluster of genotype A strains, HBV shows an exceptional genetic variability in this small country, unprecedented in sub-Saharan Africa. Despite this exceptional genetic variability, not a single genotype E virus was found indicating that this country does not belong to the genotype E crescent, but is east of an emerging African genotype E/A1 divide.