Figure. . Phylogenetic trees showing genetic relationships between sequences of vaccine-derived poliovirus (VDPV) isolates. The trees are based on nucleotide sequence alignments of various subgenomic regions. Multiple sequence alignments were performed with CLC Main Workbench 5.7.2 software (CLC bio, Aarhus, Denmark). Phylograms were constructed with MEGA 4 (http://megasoftware.net/mega4/mega.html), using the Jukes-Cantor algorithm for genetic distance determination and the neighbor-joining method. The robustness of the resulting trees was assessed with 1,000 bootstrap replications. A) Tree built from 712-bp fragments of the 5′–untranslated region (nt 36–747, with reference to Sabin 2 nucleotide numbering). B) Tree built from 2,637-bp fragments of the P1 region (nt 748–3,384). C) Tree built from 1,725-bp fragments of the P2 region (nt 3,385–5,109). D) Tree built from 2,259-bp fragments of the P3 region (nt 5,110–7,368). Names (isolate name-accession no.) are VDPV isolates recovered in Madagascar in 2011, 2005, and 2001–2002. Sequences of other isolates (CV-A11, 13, and 17) from Madagascar were also used. The percentage of bootstrap replicates is indicated at nodes if >70%. The length of branches is proportional to the number of nucleotide differences (percent divergence).Scale bars indicate genetic distances.