Figure 1.
Phylogenetic tree of Stx2 subtypes by the neighbor-joining method. The neighbor-joining tree was inferred from comparison of combined (A and B) holotoxin amino acid sequences of all Stx2 subtypes. Numbers on the tree indicate bootstrap values calculated for 1000 subsets for branch points >50%. Bar, 0.05 substitutions per site. Stx2 subtypes are indicated by different colors. An extended version of this tree is available as Fig. S2.