Biochemical and genetic peculiarities and the phylogenetic relationship of the non-main subspecies in the general scheme of the plague agent evolution

Abstract

We have completed a comparative analysis of the biochemical and genetic characteristics of Yersinia pestis strains belonging to the main (highly virulent) and non-main (selective virulence) subspecies (ssp.) to elucidate the phylogenetic relationship of the non-main ssp. in the general scheme of the plague agent evolution. It has been established that several metabolic genes such as napA (nitrate reduction), rhaS (rhamnose fermentation), melB (melibiose fermentation), and iclR (isocytrate lyase production) have undergone reductive evolution in the Y. pestis main ssp. strains but remain intact in the strains of the non-main ssp. Sequencing of the genes encoding the differential biochemical properties used for intraspecific classification of the plague agent as well as other housekeeping genes showed that the non-main ssp. strains are the most evolutionarily ancient forms of Y. pestis. Of the non-main ssp., the caucasica ssp. strains are the most ancient, lacking the plasmid of pesticinogenicity pPst and containing the genes encoding wild-type differential biochemical characteristics, similar to the Yersinia pseudotuberculosis strains. © 2012 Springer Science+Business Media New York.