Phylogenetic analysis of the NS5B partial genomic region (256 nt, 8302–8556) of HCV G1 strains. Genetic distance was estimated by Kimura 2 parameters and phylogenetic tree was constructed with the Neighbor joining method. Bootstrap values over 50% are shown in the tree. Isolates are designated by their GenBank accession number, followed by their country of origin, except for Venezuelan ones, which are numbered and preceded by a C. G1a sequences harboring D310N substitution were included, and a similar number of sequences not harboring these mutations, from Venezuela (n = 23), Brazil (BRA, n = 8) and USA (n = 6). The same criteria of selection was applied to G1b sequences, respect to C316N substitution, from Venezuela (n = 23), Brazil (n = 6) and Asia (n = 7 from HK: Hong Kong, JAP: Japan and CHI: China). Sequences grouped in clades containing D310N or C316N substitutions are shown in brackets. Percent identities over 98% are shown for these clades.