Hepatitis G virus (HGV): current perspectives.

Five viruses are usually associated with hepatitis in humans: A-E. In addition to these viruses as aetiological agents of hepatitis, there remain a number of patients with hepatitis in whom no virus could be identified. It was therefore postulated that there may be other agents which may be causing hepatitis. Recently, two viruses have been associated with hepatitis: hepatitis G virus (HGV), and transfusion transmissible virus (TTV). Hepatitis G virus (HGV) is a single stranded RNA virus which represents a newly discovered virus belonging to the flavivirus family. HGV is distinct from hepatitis C virus (HCV) and the newly discovered GBV-A and GBV-B agents, while GBV-C represents an isolate of HGV. The structure of the HGV genome resembles that of HCV. HGV replicates in peripheral blood cells, while replication in liver cells has not been observed till date. Diagnosis of HGV infection is mainly by use of polymerase chain reaction (PCR), as serological techniques are still being developed. Epidemiological data indicate that the virus is prevalent throughout the world, including India and is transmitted via blood/blood products, sexually and vertically from infected mothers to children. The relationship between infection with the virus and presence of liver pathology is controversial and has not been proven beyond doubt, as majority of patients with HGV have no detectable evidence of disease.