[Infectious-toxic model of plague in mice]

To develop infectious-toxic model of plague in mice and to assess perspectives of its use for selection of new vaccine preparations.

Cells of virulent strains of Yersinia pestis 231 and 231 FI- incubated in lysates of human erythrocytes for their activation as well as suspensions of these strains in isotonic solution of NaCl were used for subcutaneous inoculation of infection-nanve and immune mice.

It was shown that activated cultures were characterized by maximal virulence (LD50 = 1-3 CFU) and caused rapid infection--mean length of survival reduced on 1 - 3 days (P < or = 0.01). Vaccine strain EV used by conventional way of inoculation (suspension in isotonic solution of NaCl) induced strong antibacterial immunity (index of immunity--10(5)), whereas activated (in lysate of erythrocytes) cells of Y. pestis 231 strain overcame it (index of immunity--10(2)). LD50 value of Y. pestis 231 FI- for immune and nanve animals was 3 m.c. (1 CFU), which demonstrates the absence of ability of EV strain to induce antitoxic immunity in the macroorganism.

Use of two models of infection allows to make more adequate prognosis of efficacy for relevant vaccine preparations.