Fig. 2

Phylogenetic tree of C. diphtheriae. The tree was obtained using ClonalFrameML and was rooted using C. rouxii and C. belfantii isolates (see supplementary material). The main lineages Mitis and Gravis are labeled, and their branches are drawn using purple and green, respectively. The first (internal) circle around the tree corresponds to the three strain subsets (red, recent clinical isolates; blue, reference strains; gray, older clinical isolates). The second circle (stars) gives the toxigenic status. The third circle corresponds to biovars Mitis (purple), Gravis (green), and Belfanti (yellow). The next three circles indicate the presence of the spuA-associated gene cluster; DIP357 = spuA gene. The positions of reference strains PW8, NCTC13129, and NCTC10648 are indicated. The scale bar gives the number of nucleotide substitutions per site