GB virus C

Abstract

GBV-C is a flavivirus-like enveloped RNA virus measuring 50-100 nm in diameter and bands in sucrose at a peak density of 1.08-1.13 g/cm3. The isolated agent was not a single virus, but two related viruses, termed GB virus A (GBV-A) and GB virus B (GBV-B). Further, molecular studies designed to determine the prevalence of these viruses in the human population resulted in the isolation of a third related virus, GB virus C (GBV-C). This virus was later described as hepatitis G virus. It possesses long, non-translated sequences both upstream and downstream, the ORF, 533 and 312 nucleotides, respectively. Determination of the genome-length sequences of the GB viruses revealed that each genetically related to one another and to hepatitis C virus (HCV). Currently, GBV-A and GBV-B have only been detected in non-human primates, while GBV-C has only been detected naturally in humans. GBV-C encodes at least two distinct envelope proteins (E1 and E2) and evidence suggests further post-translational cleavage of E2. Both proteins contain sugar moieties that substantially increase their molecular mass and a number of cysteine residues present suggests that they possess extensive tertiary structure.