Direct evidence for GB virus C/hepatitis G virus (GBV-C/HGV) superinfection: elimination of resident viral strain by donor strain in a patient undergoing liver transplantation.

The viral genome of GB virus C/hepatitis G virus (GBV-C/HGV), a single-strand RNA virus, is subject to considerable variability and at least four genotypes have been suggested based on phylogenetic analysis. While co-infection of GBV-C/HGV with other infectious agents such as hepatitis C virus (HCV) has been frequently observed, there is no report whether or not co-infection and/or superinfection occurs among different GBV-C/HGV strains. By studying a GBV-C/HGV positive recipient/donor pair in the context of undergoing liver transplantation, we have sequenced multiple clones derived from serum samples serially collected over four years. Detailed phylogenetic analyses have been performed with these sequences. The donor was infected with GBV-C/HGV genotype 1 and this strain completely replaced recipient GBV-C/HGV strain (genotype 2) after liver transplantation. The recipient's original viral strain became undetectable during follow-up. Sequence analysis failed to identify genetic recombination between the two genotypes, at least in whole structural domain. This study, therefore, provides direct evidence for GBV-C/HGV superinfection of one strain by another with one of them predominating probably due to replication competition.