PCR amplification and phylogenetic analysis of groESL operon sequences from Ehrlichia ewingii and Ehrlichia muris

Abstract

Broad-range PCR primers were used to amplify part of the groESL operon of the canine pathogen Ehrlichia ewingii, recently recognized as a human pathogen, and the murine pathogen Ehrlichia muris. Phylogenetic analysis supported the relationships among Ehrlichia species previously determined by comparison of 16S rRNA gene sequences. These sequences provide additional PCR targets for species for which few gene sequences have been determined.

FIG. 1

Phylogenetic relationships among Ehrlichia species and related bacteria derived from analysis of groESL gene sequences. Phylogenetic analyses used PAUP (version 4.0b2); (26) and both parsimony and neighbor-joining search algorithms. Parsimony analyses used the heuristic search option with tree bisection-reconnection branch swapping, MULPARS, and random addition of taxa (100 replicates). Neighbor-joining analyses used minimum evolution as the objective criterion, with maximum likelihood used to estimate the transition-to-transversion ratio and nucleotide base frequencies (settings correspond to the Hasegawa-Kishino-Yano [1985] model of nucleotide sequence evolution). Tree support was assessed by using the nonparametric bootstrap (1,000 replicates). The values adjacent to the branches are parsimony/neighbor-joining bootstrap proportions.