cospeciation between virus isolates and their primate hosts

GB viruses A and C (GBV-A and GBV-C) have been isolated from humans and non-human primates. Phylogenetic analysis based on full-length poly-proteins suggests that these two viruses have a common ancestor. It has now been determined that analysis of subgenomic amino acid sequences in the E2 and NS5 regions of GBV-A and a 345 nucleotide segment in the 5 « non-coding (5«NC) region was able to reproduce the phylogenetic relationships obtained by complete polyprotein sequences analysis. Using 5«NC sequences from databases, GBV-A isolates were discriminated into eight gen-etic groups, each one closely associated with specific primate hosts. Phylogenetic analyses per-formed on sequences from the e-globin genes of primate hosts on one hand and complete poly-protein sequences from GBV-A and GBV-C isolates on the other suggest that a mechanism of co-speciation could be involved in virus evolution over a period of 35 million years. Although the International Committee on Taxonomy of Viruses has not yet officially established their taxonomic status, the recently described GB viruses A, B and C (GBV-A, GBV-B and GBV-C) have been provisionally classified into the family Flaviviridae on the basis of their structure, genomic organization and sequences. Within this family, the most-closely related species is hepatitis C virus (HCV, genus Hepacivirus). GBV-C was isolated first from humans and more recently from chimpanzees (Adams et al., 1998; Birkenmeyer e