Strain from a novel subfamily of hepatitis G virus/hepatitis GB virus C isolated from a Japanese patient: sequence analysis of the envelope 1 region.

Since two closely related gene isolates of a novel flavivirus, designated hepatitis G virus (HGV) and hepatitis GB virus C (GBV-C), respectively, were first identified (2, 3), 11 HGV/ GBV-C-related gene sequences have been reported. We report here a gene sequence for the envelope 1 (E1) region of an HGV/GBV-C strain obtained from a Japanese patient who had positive titers for HGV, HCV, and HBV. The determined nucleotide sequences and the deduced amino acid residues were found to be different from those previously reported (Table 1; Fig. 1 and 2). Specifically, our E1 gene showed 0.5 to 6.9% and 8.5 to 13.7% differences when its amino acid and nucleotide sequences, respectively, were compared with those reported so far. Although the nucleotide sequences of our E1 gene and previously reported E1 genes were shown to be relatively diverse (86.3 to 91.5% homology), their amino acid residues were highly conserved between strains (93.1 to 99.5% homology). This indicates that most of the nucleotide changes in the HGV/GBV-C genes, including ours, are silent. Our result suggests that the E1 gene reported here is likely derived from a novel HGV/GBV-C strain, which we have named HGV-T1.