Genotype H: a new Amerindian genotype of hepatitis B virus revealed in Central America

Abstract

The complete genomes were sequenced for ten hepatitis B virus (HBV) strains. Two of them, from Spain and Sweden, were most similar to genotype D, although encoding d specificity. Five of them were from Central America and belonged to genotype F. Two strains from Nicaragua and one from Los Angeles, USA, showed divergences of 3n1-4n1 % within the small S gene from genotype F strains and were recognized previously as a divergent clade within genotype F. The complete genomes of the two genotype D strains were found to differ from published genotype D strains by 2n8-4n6 %. Their S genes encoded Lys 122 , Thr 127 and Lys 160 , corresponding to the putative new subtype adw3 within this genotype, previously known to specify ayw2, ayw3 or, rarely, ayw4. The complete genomes of the three divergent strains diverged by 0n8-2n5 % from each other, 7n2-10n2 % from genotype F strains and 13n2-15n7 % from other HBV strains. Since pairwise comparisons of 82 complete HBV genomes of intratypic and intertypic divergences ranged from 0n1 to 7n4 % and 6n8 to 17n1 %, respectively, the three sequenced strains should represent a new HBV genotype, for which the designation H is proposed. In the polymerase region, the three strains had 16 unique conserved amino acid residues not present in genotype F strains. So far, genotype H has been encountered in Nicaragua, Mexico and California. Phylogenetic analysis of the complete genomes and subgenomes of the three strains showed them clustering with genotype F but forming a separate branch supported by 100 % bootstrap. Being most similar to genotype F, known to be an Amerindian genotype, genotype H has most likely split off from genotype F within the New World.

Tracing the history of hepatitis B virus genotype D in western Japan

“…HBV has approximately 3,200 bases that can be divided into several genotypes by sequence divergence, with 8 genotypes (A-H) reported [Okamoto et al, 1988;Norder et al, 1994;Stuyver et al, 2000;Arauz-Ruiz et al, 2002]. These genotypes have a distinct geographical distribution, with genotypes A (HBV/A) and HBV/ D predominant in Europe, Middle East, Central Asia, Siberia, and America, HBV/B and HBV/C in East Asia, and HBV/E in Africa.…”

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“…HBV isolates have been classified into eight genotypes (A to H), considering a divergence of more than 8% in the entire virus genomic sequence (Okamoto et al 1988, Norder et al 1994, Stuyver et al 2000, Arauz-Ruiz et al 2002. HCV is a positive-sense, single-stranded RNA virus that presents a high mutation rate (10 -3 substitutions/site/year).…”

Virological outcomes in patients infected chronically with hepatitis B virus genotype A in comparison with genotypes B and C

“…Genotype H is genetically close to F and distributes in Central America [Arauz-Ruiz et al, 2002]. Genotype G occurs very rarely [Stuyver et al, 2000;Chu et al, 2003;Kato et al, 2004], and is always co-infected with HBV of the other genotypes ].…”