Yersinia pestis pathogenicity

Abstract

Yersinia pestis belongs to those pathogenic bacteria which produce lipopolysaccharide (LPS) having the function of a toxin. In order to make a toxic effect the polymer must be separated from the cell outer membrane and presented to the immunocompetent cell receptors of the host in the functionally active form. In this review data of russian and foreign investigators on Y. pestis toxigenic properties was presented. Results of the authors' own experiments showing that Y. pestis is able to export LPS into the surrounding medium are included. This process is a natural function of the living cell, is realized at 37 degrees C and is strictly dependent on the expression of Y. pestis genes of extrachromosomal inheritance, pMT1, pCD1, pPCPl. By the use of isogenic variants of Y. pestis EV76 vaccine strain and virulent 231 strain containing different plasmid combinations, it was established that maximum contribution in the activation of «high-temperature» LPS and its transformation into extracellular form made the proteins encoded by pCD1. The significance of the «murine» toxin encoded by pMT1 plasmid was less pronounced. The participation of pPCPl plasmid in the toxic effect was not discovered. The role of Y. pestis capsular substance and the significance of biologically active factors in the realization of Y. pestis LPS toxic potential is discussed. Functional relationship between translocation of the proteins encoded by plasmids and Y. pestis toxigenicity suggests Y. pestis biological uniqueness.