IDENTIFICATION OF A SINGLE GENOTYPE OF HEPATITIS-G VIRUS BY COMPARISON OF ONE COMPLETE GENOME FROM A HEALTHY CARRIER WITH 8 FROM PATIENTS WITH HEPATITIS

Different isolates of a putative hepatitis virus called hepatitis GB v irus C or hepatitis G virus (HGV) have been cloned recently from patie nts with hepatitis. This virus has also been found commonly in healthy carriers. We have cloned and sequenced a complete HGV genome, designa ted HGVCN, from a healthy Chinese blood donor, HGVCN shares 85.8-90.0% nucleotide sequence identity and 95.4-97.5% amino acid identity with the eight available full-length HGV genomes. Furthermore, the majority (82.8%) of the nucleotide substitutions found in HGVCN were synonymou s and a fairly uniform distribution of changes was found across the en tire genome without identification of any hypervariable region. When c ompared with the African isolates GBVC and GBVC-EA, the HGVCN-encoded polyprotein contained a 31 amino acid N-terminal extension which was p redicted to be a defective core-like sequence. The sequences of the HG V E1 and E2 proteins displayed unique motifs and were highly conserved , Phylogenetic analysis revealed that all nine complete HGV isolates w ere closely related and that HGVCN grouped with the other Chinese HGV isolate (HGVC964), Taken together, our findings suggest that there is one single genotype of HGV and that the HGV genome cloned from the hea lthy carrier is not significantly different from those derived from pa tient sera.