Genotype X/C recombinant (putative genotype I) of hepatitis B virus is rare in Hanoi,Vietnam—genotypes B4 and C1 predominate

There are eight known genotypes of hepatitis B virus, A–H, and several subgenotypes, with rather well‐defined geographic distributions. HBV genotypes were evaluated in 153 serum samples from Hanoi, Vietnam. Of the 87 samples that could be genotyped, genotype B was found in 67 (77%) and genotype C in 19 (22%). All genotype C strains were of subgenotype C1, and the majority of genotype B strains were B4, while a few were B2. The genotype X/C recombinant strain, identified previously in Swedish patients of indigenous Vietnamese origin, was found in one sample. This variant, proposed to be classified as genotype I, has been found recently also by others in Vietnam and Laos. The current study indicates that the genotype X/C recombinant may represent approximately 1% of the HBV strains circulating in Vietnam. J. Med. Virol. 82:1327–1333, 2010. © 2010 Wiley‐Liss, Inc.