Experimental Evaluation of Application of the Vaccine Strain Yersinia pestis EV NIIEG in Combination with Immune-Modulators

Abstract. Objective of the work was to conduct a comparative assessment of the immune-modulating effect of the combined use of Yersinia pestis EV NIIEG vaccine strain with Polyoxidonium and Ingaron preparations on a BALB/c mouse model. Materials and methods. Mice of the BALB/c line were immunized subcutaneously with Yersinia pestis EV NIIEG culture at a dose of 2.5 10 4 m.c. (1st group), in combination with Ingaron at a dose of 150 IU (2nd group) or with Polyoxidonium at a dose of 4 мg (3rd group), the 4th group is intact mice. On days 3, 7, 21 and 90 after immunization, the subpopulation composition of lymphocytes, the production of mediators of the cellular response (INF-ɣ and IL-10), the titers of specific antibodies to the capsular antigen of plague microbe (F1), the nuclear apparatus of lymphocytes, and the nature of histological changes in the organs of mice were determined. Characterization of immunogenic (protective) activity of the combined use of Y. pestis EV NIIEG with immune-modulators against Y. pestis 231 in experiments on BALB/c mice was performed on the 21st day after immunization through determining the number of dead animals and their average life expectancy. Results and discussion . The combined administration of Y. pestis EV NIIEG vaccine strain with Polyoxidonium or Ingaron to experimental animals allowed us to establish differences in the response of the immune system of biomodels, due to the mechanism of action of a specific immune-modulator. It has been established that both Polyoxidonium and Ingaron combined with Y. pestis EV NIIEG enhance the response of immune-competent cells in experimental animals, contribute to the activation of the humoral response and the production of mediators of the cellular response, do not have a damaging effect on the tissue of the macroorganism. At the same time, the efficacy of using combined vaccination of Y. pestis EV NIIEG with immune-modulators in the inoculation test is confirmed for Polyoxidonium only.