[In vivo and in vitro study of plasmid fragments from Ca2+-dependent Yersinia pestis (Lehmann, Neumann)].

The bank of the HindIII, EcoRI and PstI fragments of Yersinia pestis Ca(2+)-dependence plasmid (pCaD) was constructed and used as molecular probes, combined with the restriction analysis to map pCaD. Experiments on laboratory animals showed two subfragments of the fifth HindIII fragment to impart virulence, invasiveness to the plasmidless avirulent strains of Y. pestis, Y. pseudotuberculosis and Escherichia coli, and the protective activity to Y. pestis clones, while the original fifth HindIII fragment possessed no such property.