EFFECT OF EXTRACHROMOSOMAL ELEMENTS OF HEREDITY ON TOXIC PROPERTIES OF YERSINIA PESTIS

AIM: Elucidation of the role of extrachromosomal elements of heredity in manifestations of toxic properties of Yersinia pestis. MATERIALS AND METHODS: The study was carried out in vac- cine strain Y pestis EV76 (pMT1, pCD1, pPCP1) and non-plasmid variants of vaccine EV76 (pMT1⁻, pCD1⁻, pPCP1⁻) and virulent 231 (pMT1⁻, pCD1⁻, pPCP1⁻) strains of Y pestis. Presence of functionally active form of lipopolysaccharide (LPS) in.the incubation medium of the bacteria was evaluated via toxicity of supernatant of Y pestis for intactanimals (infec- tion-toxic shock) and mice sensitized by D-GalN. RESULTS: 37°C cultures of Y pestis EV76 containing a full amount of plasmids were established to release LPS into the environment. Non-plasmid variants of both vaccine and virulent strains of Y.pestis pMT-, pCD1-, pPCP1- do not have this ability. Separation of LPS from cell wall was detected in live bacteria of plague infectious agent. This process is assumed to be coupled with translocation of proteins coded by pMT1, pCD 1, pPCP 1 plasmids from the cell into the environment. CONCLUSION: Functional inter-connection between extrachromosomal elements of heredity and toxic activity of Y pestis LPS is established for the first time.