FIG. 2.

Evolutionary relationship between all C. trachomatis prototype strains and the 43 types of genetic variants. The neighbor-joining phylogenetic tree is based on the number of nucleotide differences observed among the ompA sequences to better illustrate the genetic distances between genetic variants. Kimura two-parameter and gamma models yielded similar topologies. The tree was rooted using the ompA sequence from C. muridarum strain MoPn. Bootstrap values (1,000 replicates) are shown next to the branch nodes. The traditional ompA serogroups (B, C, and Intermediate) are shown above the three major branches of the tree. All types of genetic variants and reference strains belonging to the same genotype are represented by the same color together with the respective prototype strain. Values in parentheses indicate the number of variant specimens represented by that type of genetic variant and the total number of variant specimens found for the same ompA genotype. Types of genetic variants that had never been described before are represented by yellow circles.