[Significance of coinfection with hepatitis G virus for chronic hepatitis C--a review of the literature].

BACKGROUND: The clinical significance of the recently discovered hepatitis C virus (HGV/GB virus C (GBV-C) is not conclusively clarified. The aim of this analysis was to evaluate the frequency of HGV/GBV-C coinfection at existing hepatitis C infection, the significance for the course of the liver disease, and its response to antiviral therapy. METHODS: The literature available by medline and the PubMed Retrieval System as well as abstracts of recent German, European, and American conferences on liver diseases (GASL, EASL, ASSLU) concerning HCV/GBV-C-coinfection were analyzed. RESULTS: We identified 66 references with 5,388 patients suffering from HCV-infection. 941 (17.5%) were coinfected with GBV-C. Excluding some groups at risk (intravenous drug abusers, dialysis patients, patients after liver transplantation), the rate of coinfection varied significantly in respect to geography: 20.5% in European vs. 10.9% in Japan (p < 0.0001). Additionally, coinfection occurred in 38% of intravenous drug users. The studies showed that coinfection was related to the frequency of blood transfusions. Furthermore, the parenteral transmission route of GBV-C was generally confirmed. Overall GBV-C does not seem to have any negative influence on the course of HCV-related chronic liver disease or the development of chronicity of acute hepatitis C infection, nor does it have any influence on histology, transaminase-levels or response of HCV to antiviral therapy; GBV-C was shown to be sensitive to interferon-alpha with a relapse rate up to 53% comparable to HCV. There is no correlation between response of HCV and GBV-C to interferon. CONCLUSION: This analysis of the published data concerning coinfection of HCV and HGV/GBV-C revealed no influence of GBV-C on the course of HCV-related liver disease (clinical, biochemical, histological). GBV-C does not modify the response rate of HCV to interferon-alpha, but GBV-C is sensitive to interferon with high relapse rates.