Submitted to: International Meeting of the European Society for Chlamydia Research
Publication Type: Abstract Only
Publication Acceptance Date: 5/10/2000
Publication Date: N/A
Technical Abstract: Our goal was to determine the level of support that could be obtained for the new chlamydial taxonomy through phylogenetic analyses of GroEL, KDO- transferase, MOMP, 60-Kda cysteine-rich protein, and cysteine-rich lipoprotein. We determined the evolution of these genes using a number of phylogenetic algorithms, including neighbor joining, maximum likelihood, parsimony and quartet puzzling. The robustness of the resulting trees was evaluated using bootstrap and reliability values, saturation plots, and insertion-deletion analyses. The overall structure of all trees was congruent with the rooted 16S rRNA and 23S rRNA phylogeny for the chlamydiales. There was no evidence for lateral gene transfer above the species level in any of the genes. Differentiation ratios, which contrast the genetic variation within and between clusters of isolates, showed nine clusters of sequences differentiated at the species level or higher in analyses of each of the five coding genes. Our results also showed the tw genera, Chlamydia and Chlamydophila, to be monophyletic lineages, as was suggested by previous studies of the 16S rRNA, Rnase P RNA, and MOMP. Saturation plots showed that genetic distances between species in the two genera were larger than genetic distances between species within each genus alone, even for such divergent species as C. pecorum and C. pneumoniae. The five coding genes provided clear genetic evidence for the existence of nine differentiated species in the Chlamydiaceae, and for both the monophyly and genetic differentiation of the two new genera. This finding is congruent with the ribosomal and biological observations that led to the proposal of nine species in the Chlamydiaceae.