Interactions between GB virus type C and HIV

GB virus C (GBV-C, also known as hepatitis G virus) commonly causes human infection. Genetically, it is closely related to hepatitis C virus, but GBV-C appears to grow primarily in lymphocytes, not hepatocytes. Although it causes persistent infection in about 25% to 50% of infected individuals, numerous studies have failed to connect GBV-C with any disease process. GBV-C is transmitted sexually, parenterally, and vertically, and due to these shared modes of transmission, coinfection is common among HIV-infected individuals. Of 10 studies done of HIV-GBV-C coinfection, eight found a beneficial effect of GBV-C viremia on HIVrelated mortality or response to therapy. The mechanism by which GBV-C may improve survival of HIV-positive people is not known; however, in vitro studies suggest that GBV-C inhibits HIV replication, and preliminary data also point toward alterations in cytokine and/or chemokine expression by GBV-C-infected cells.