Three different GB virus C/hepatitis G virus genotypes. Phylogenetic analysis and a genotyping assay based on restriction fragment length polymorphism

The 5'-untranslated region (5'-UTR) sequences of 33 GB virus C/hepatitis G virus (GBV-C/HGV) obtained from different geographic areas were determined through reverse transcription polymerase chain reaction and dideoxy chain termination sequencing, the alignment of sequences, the estimation of the number of nucleotide substitution per site, and construction of phylogenetic trees. The 5'-UTR of GBV-HGV was found to be heterogeneous, with 70.9-99.5% homology. Three distinct phylogenetic branches mere observed consistently in all phylogenetic trees, GBV-C is the prototype for one, HGV for another, and there is a new branch which consisted of GBV-C/HGV isolates from Asia. Genotype-specific restriction sites for the restriction enzymes, ScrFI and BsmFI, were identified, and a simple restriction fragment polymorphism analysis was developed for genotyping. These data provide evidence that GBV-C/HGV consists of three different genotypes. Our simple genotyping assay will also provide a tool for epidemiological studies of GBV-C/HGV infection.