[GB virus-C/hepatitis G virus--discovery, epidemiology, diagnosis and clinical relevance].

Recently, two isolates of a new virus, designated GB virus C (GBV-C) and hepatitis G virus (HGV) were identified. Genomic organization place them in the family Flaviviridae, which includes HCV. A classification of GBV-C/HGV strains into at least three genotypes (West Africa, Europe/North America, Asia) has been proposed. GBV-C/HGV has a positive-stranded, linear RNA genome possessing a large open reading frame that encodes a single large polyprotein. As a possible genomic defect no core protein has yet been identified in GBV-C/HGV isolates. Whether GBV-C/HGV can be classified as a hepatotropic virus with replication in the liver is under discussion. The prevalence in the general population is high (2%). GBV-C/HGV is transmitted parenterally e.g., by transfusion of blood and blood products. Furthermore, cases of vertical and horizontal transmission are reported. Detection of GBV-C/HGV infection is exclusively possible by reverse transcription polymerase chain reaction (RT PCR). E2-specific antibodies are associated with loss of detectable GBV-C/HGV RNA and appear to indicate recovery from GBV-C/HGV infection. An acute icteric state with transient elevation of aminotransferases in association with GBV-C/HGV infection may exist. These cases are rare and approximately only 0.3% of persons with acute viral hepatitis are infected with GBV-C/HGV alone. Whether GBV-C/HGV is a cause of fulminant hepatic failure has not yet been proven. Persistent viremia of the GBV-C/HGV infection is frequent but is not related to chronic liver disease. Since no other chronic diseases associated with GBV-C/HGV infection could yet be identified, chronic GBV-C/HGV infections appear to be without clinical significance. GBV-C/HGV and hepatitis B or C virus (HBV, HCV) coinfection seem not to interfere with the outcome of HBV-respective HCV-related liver disease. The cause of the majority of cases with non-A-E viral hepatitis remains unknown and other yet undiscovered hepatic viruses must exist.