ML tree based on 309 partial NS5B sequences of HCV-1, corresponding to nt 8316–8620 in the referenced H77 genome. The subtype is denoted at the right-hand side of the tree. The 16 isolates characterized in this study are labelled by filled circles. The seven isolates we reported recently are indicated by open circles (Li et al., 2013), whilst the 16 filled triangles mark the isolates that were assigned to the various HCV-1 subtypes in the consensus paper (Simmonds et al., 2005). To simplify the tree, isolates of subtype 1a, 1b and cluster PH-26 sequences are collapsed into single bold open circles. For other details, see legend for Fig. 1.