Summary auto-generated
This study analyzed the complete genomic sequences of two GB virus A (GBV-A) variants isolated from captive monkeys: GBV-Amx from a marmoset and GBV-Atri from an owl monkey. The researchers used RT-PCR to sequence these viruses and compared them to previously identified GBV-A strains and related viruses. GBV-Amx is 9586 nucleotides with 65-66% identity to other GBV-A variants, while GBV-Atri is 9625 nucleotides with 59% identity. Both viruses encode polyproteins with conserved functional domains typical of Flaviviridae family members, including protease and replicase regions. Unlike other flaviviruses, neither GBV-A variant encodes a basic core-like protein. Phylogenetic analysis revealed that GBV-A variants show genetic diversity comparable to hepatitis C virus types, yet share greater evolutionary similarity with GBV-C than with HCV. The findings support the classification of GBV-A and GBV-C as separate genera within Flaviviridae, distinct from both GBV-B and HCV. The results suggest GBV-A may have originated from primate species, with Saguinus nigricollus tamarins potentially being the source of the prototype strain.
Key findings
- GBV-A variants from different primate species show 52-79% genetic identity, breaking into at least five distinct genotypes with species-specific clustering
- GBV-A variants lack a basic core-like protein but retain conserved protease and replicase motifs needed for viral replication
- Phylogenetic analysis places GBV-A and GBV-C in a single evolutionary genus, separate from GBV-B and HCV, with genetic distances greater than 2.3 amino acid substitutions per position between groups
- GBV-A variants demonstrate sequence variability similar to hepatitis C virus types, with conservation highest in functionally critical NS3 and NS5B regions
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Abstract
The recent isolation of GB viruses A and B from GB agent infected tamarins and their lack of involvement in human hepatitis has sparked interest in the origin of these viruses. Several healthy non-human primate species have been shown to harbour sequences 52-79% identical to the GBV-A 5' nontranslated region. In this paper we report the near genome length sequence of GBV-Amx 70047 and GBV-Atri 1122. These sequences support previous observations about the genomic organization of GBV-A and provide insight into the genomic variability within this virus genus. Although the GBV-A variant polyproteins possess many motifs conserved between other members of the Flaviviridae, they do not encode a basic core-like protein. Amino acid sequence comparisons and phylogenetic analysis demonstrate variability within the GBV-A genus similar to that observed between hepatitis C virus (HCV) types. However, genomic organization and disease association demonstrate a closer evolutionary relationship to GBV-C than to HCV.