Maximum likelihood phylogenetic tree analysis of HCV strains using the GTR plus gamma model. Strains in the tree are shown by their accession number and their genotypes are indicated between parentheses for strains previously described (for accession numbers, genotypes and geographic origin of isolation see Table 1). Strain H23, isolated from a Uruguayan hemophiliac patient is shown by name. Numbers at each branch of the tree show aLRT values. Bars at the bottom of the trees show distance. The phylogeny for the 5'NCR and core region is shown in (A) and (B) respectively.