Molecular phylogenetic analysis of Orientia tsutsugamushi based on the groES and groEL genes.

DNA sequences encoding the GroES and GroEL proteins of Orientia tsutsugamushi were amplified by the PCR and sequenced. Pairwise alignment of full-length groES and groEL gene sequences indicated high sequence similarity (90.4-100% and 90.3-100%) in O. tsutsugamushi, suggesting that these genes are good candidates for the molecular diagnosis and phylogenetic analysis of scrub typhus. Comparisons of the 56-kD type-specific antigen (TSA) protein gene and the groES and groEL genes showed that genotypes based on the 56-kD TSA gene were not related to a cluster containing the groES and groEL genes in a dendrogram, suggesting that a gene rearrangement may be associated with homologous recombination in mites.