Clinical course of chronic hepatitis C virus infection is not influenced by concurrent hepatitis G virus infection.

To determine the effects of hepatitis G virus (HGV) infection on chronic hepatitis C virus infection (HCV) and to evaluate HGV response to interferon, we investigated HGV RNA by polymerase chain reaction in 247 Japanese patients with chronic HCV infection (166 men and 81 women; 124 had chronic hepatitis and 26 cirrhosis, and 97 hepatocellular carcinoma). HGV RNA was detectable in 22 (8.9%) patients, among whom 21 were men: this male predominance was statistically significant (P < 0.01). There were no differences in age, aminotransferase level, stage of liver disease, HCV RNA level by competitive polymerase chain reaction, genotype, or interferon response to HCV RNA between patients with HCV infection alone or with HCV/HGV coinfection. Sustained elimination of HGV RNA was found in 28.6% of the 14 treated patients with HCV/HGV coinfection. In the 14 treated patients, sustained elimination of both viruses was seen in two, HCV alone was eliminated in two, and HGV alone was eliminated in two. Aminotransferase level improvement by interferon treatment was associated with clearance of HCV, but not of HGV. Thus, HGV infection had no apparent effects on HCV infection, and the sensitivity of HGV to interferon is comparable to but independent of HCV.