A Previously Unrecognized Sixth Genotype Of Gb Virus C Revealed By Analysis Of 5 '-Untranslated Region Sequences

GB virus C (GBV-C) is a positive-strand RNA virus that infects a large proportion of the world's human population. It has been classified tentatively as a member of the Flaviviridae family and has been shown to exist as a group of five closely related genotypes. Recently, we reported the first full-length genome sequence of a genotype 5 isolate from South Africa [Muerhoff et al. (2005): J Gen Virol 86: 1729-1735]. As part of the analysis of that sequence, a phylogenetic tree was elucidated from the 5'-untranslated region (UTR) that showed excellent congruence to the tree produced by analysis of complete open reading frame sequences. When 5'-UTR analysis was broadened subsequently to include additional isolates from around the globe, a heretofore unrecogrized GBV-C genotype was discovered in Indonesia. When first reported in 2000 [Handajani et al. (2000): J Clin Microbiol 38:662-668], these isolates were described as constituting a novel fifth genotype. However, comparison to isolates from the then-known fourth and fifth genotypes (from Myanmar/ Vietnam and South Africa, respectively) was not performed. A dataset of 121 GBV-C 5'-UTR sequences was complied and included representatives of the fourth and fifth genotypes as well as the "novel" Indonesian sequences and demonstrated, with strong support via boot-strap analysis, the existence of a sixth GBV-C genotype among infected individuals in Indonesia. The discovery of this sixth genotype emphasizes the diverse nature of GBV-C isolates and may have important implications for the interpretation of studies involving GBV-C/HIV co-infected individuals.