HIV and GB virus C--can two viruses be better than one?

GB virus C (GBV-C), an RNA virus in the Flaviviridae family, is a close relative of the hepatitis C virus. Although it has been shown that many people worldwide are infected with this virus, no clear association between the virus and a known disease state has been demonstrated. GBV-C has been shown to replicate in human peripheral-blood mononuclear cells in vitro, and it commonly coinfects patients with human immunodeficiency virus (HIV). GBV-C is transmitted through predominantly parenteral routes and has a high seroprevalence among intravenous-drug users. Nonetheless, the sexual transmission of GBV-C has also been demonstrated recently. Infection with or carriage of the virus can be quite prolonged in many people, but most eventually clear the GBV-C RNA that is detectable in peripheral blood.