| Abstract: | Two basic tendencies--formation of latent (uncultivable) form (LF) and hemin storage variability--has been revealed during study of clonal structure dynamics of Y. pestis populations in artificial soil ecosystems in long-term incubation conditions. Y. pestis populations disappeared within 3 - 6 months at 18 - 22 degrees C, whereas at 4 - 8 degrees C a subsequent replacement of vegetative cells on LF, which are capable to prolonged survival (up to 22 months) in soil with ability to reversion in the presence of abundance of nutrients, has been observed. Bacteria of virulent strain retained all determinants of pathogenicity when reverted to LF, whereas bacteria of avirulent strain (defective on plasmid of Ca-dependence), on the contrary, undergo further degradation that resulted in loss of a pgm locus and gradual disappearance of population. LF revertants of highly virulent strain restored properties of initial population and were highly virulent. |
