The T1858 variant predisposing to the precore stop mutation correlates with one of two major genotype F hepatitis B virus clades

The precore mutation G¹⁸⁹⁶A occurs frequently in anti-HBe-positive carriers of HBsAg with T¹⁸⁵⁸ in the stem of the encapsidation signal. Hepatitis B virus (HBV) genotype F, considered an Amerindian genotype, subdivides into two clades and the precore mutation occurs in Central American F strains. To investigate the relationship between substitutions at position 1858 and these clades, the precore and small S genes of 48 strains of HBV genotype F were subjected to phylogenetic analyses. Isolates of one clade, formed mainly of Central American strains, all had T¹⁸⁵⁸ and Thr⁴⁵ in the S gene, whereas in the other clade, formed mainly of South American strains and one strain from Polynesia, all had C¹⁸⁵⁸ and Leu⁴⁵. The latter strain was related to strains from Venezuela and Colombia, supporting an Amerindian contribution to the Polynesian population. The position of the Polynesian strain in the phylogenetic tree indicates that the two clades have resulted from an early split, showing a high degree of genetic stability of the stem of the HBsAg encapsidation signal.

The sequences reported in this paper have been deposited in GenBank under the accession numbers AY264387AY264401.