MUTATION-RATE OF GB VIRUS-C HEPATITIS-G VIRUS OVER THE ENTIRE GENOME AND IN SUBGENOMIC REGIONS

A patient on maintenance hemodialysis was infected with a recently dis covered putative non-A to -E hepatitis virus designated GB virus C (GB V-C) or hepatitis G virus (HGV) by transfusion. The Viral isolate was recovered from the patient soon after she turned positive for GBV-C/HG V RNA in serum (GSI85) and 8.4 years thereafter (GSI93) and the entire nucleotide sequences were determined. They both had a genomic length of 9391 nucleotides with a defective C gene made of only 42 nucleotide s. Between GSI85 and GSI93, 31 (0.33%) nucleotides were different, whi ch changed 5 (0.18%) of the encoded 2842 amino acids. Thus, GBV-C/HGV was estimated to have a mutation rate of 3.9 X 10(-4) base substitutio ns per site per year. Nucleotide conversions were distributed over sub genomic regions, except in the 5' untranslated region of 552 nucleotid es and a defective short C gene, which were conserved in sequence. The change in the putative envelope genes (E1 and E2) was no different fr om that in the entire genome with only 6 (0.35%) nucleotide substituti ons among the 1730, just 1 of which induced an amino acid conversion. Taken along with the comparison of the two isolates with the reported five GBV-C or HGV isolates, these results indicate that GBV-C/HGV woul d not have hypervariable regions and would use a strategy for Viral pe rsistence that is different from immune escape. (C) 1997 Academic Pres s.