Persistent infection mechanism of GB virus C hepatitis G virus differs from that of hepatitis C virus

Objective: Changes in the deduced amino acid sequence of the envelope 2 (E2 ) region of the GB virus C/hepatitis G virus (GBV-C/HGV) were analyzed to i nvestigate whether or not the region contributes to persistent infection wi th the virus. Methods: Eight patients with acute hepatitis C and 1 patient with acute hepatitis of unknown etiology were included in the study. GBV-C/ HGV RNA was detected in 6 patients, including the patient with hepatitis of unknown origin. The nucleotide sequence of the E2 region of hepatitis C vi rus (HCV) and GBV-C/HGV was determined by direct sequencing of polymerase c hain reaction products in 5 patients with HCV infection and in 6 patients w ith GBV-C/HGV infection twice during the period of early infection and seve ral months or years later in each patient, Results:The mean substitution ra te of the deduced amino acid sequence in the E2 region was over 100 times l ower (p < 0.001) in GBV-C/HGV (0.01 +/- 0.04/month/100 sites) than in HCV ( 2.4 +/- 1.7/month/100 sites), The amino acid sequence of the loop domain of GBV-C/HGV-E2 did not change in any of the 6 patients. On the other hand, t he sequence of the hypervariable region of HCV-E2 changed remarkably (5.9 /- 4,3/month/ 100 sites). No am ino acid substitution in the loop domain wa s observed in 7 additional patients who showed persistent GBV-C/HGV viremia for more than 2 years. Conclusion: These results indicate that changes in the amino acid sequence of the E2 region are not involved in the mechanism of persistent GEV-C/HGV infection. Copyright (C) 2000 S. Karger AG. Basel.