Abstract: | The genetic analysis of Y. pestis virulence factors accomplished in the 358 strain isogenic system allowed us to determine a minimal set of known factors providing pathogenicity. The combination of chromosomal marker Pgm+ and calcium dependence plasmid (pCad) is shown to be sufficient for preserving the virulence of Y. pestis. Experimental modelling of virulence in this microorganism by the genetic exchange methods was carried out. The reduced virulence of the strains Pgm+ and pCad+ for guinea pigs was detected. |