Hepatitis G

Introduction

GB virus C (GBV-C) is a species of virus in the Flaviviridae family which has not yet been assigned to a genus, is known to infect humans, but is not known to cause human disease. There have been reports that HIV patients coinfected with GBV-C can survive longer than those without GBV-C, but the patients may be different in other ways. There is current active research into the virus' effects on the immune system in patients coinfected with GBV-C and HIV.

History

Hepatitis G virus and GB virus C (GBV-C) are RNA viruses that were independently identified in 1995, and were subsequently found to be two isolates of the same virus. Although GBV-C was initially thought to be associated with chronic hepatitis, extensive investigation failed to identify any association between this virus and any clinical illness.

Taxonomy

GBV-C is a member of the Flaviviridae family and is phylogenetically related to hepatitis C virus but appears to replicate primarily in lymphocytes, and poorly if at all in hepatocytes. GBV-A and GBV-B are probably Tamarin viruses, while GBV-C infects humans

Human infection

The majority of immune-competent individuals appear to clear GBV-C viraemia within the first few years following infection and although the time interval between GBV-C infection and clearance of viraemia (detection of GBV-C RNA in plasma) is not known, infection may persist for decades in some individuals.

Approximately 2% of healthy US blood donors are viraemic with GBV-C, and up to 13% of blood donors have antibodies to E2 protein, indicating prior infection.

Parenteral, sexual and vertical transmission of GBV-C have all been documented, and because of shared modes of transmission, individuals infected with HIV are commonly co-infected with GBV-C. Among people with HIV infection, the prevalence of GBV-C viraemia ranges from 14 to 43%.

Some studies have suggested that co-infection with GBV-C will actually slow the progression of HIV disease.