Fig. 3

Subtyping by phylogenetic analysis of the 45 genotype D sequences from S region. The sequence dataset included subtype D1 to D10 reference sequences. The phylogenetic tree was constructed by the ML approach with the GTR + G + I substitution model (preliminary estimated to be the best substitution model for the dataset under analysis by the Models tool in MEGA6). A blue circle marks sequences from 1978 to 79, a red circle those from 1994 to 95; reference sequences are shown in bold. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. A black arrow marks sequences whose patient reported the IDU risk factor. Bootstrap values > 70 are reported (exception: the bootstrap value at the node of the branch comprising most sequences from cases reporting the IDU risk factor)