Assessment of the effect of using immunomodulatory drugs for emergency prevention of experimental plague caused by a virulent strain of the main subspecies Yersinia pestis

Abstract

Introduction. Immunomodulatory drugs (IMD) have great potential to increase the nonspecific reactivity of the organism in a set of measures for emergency prevention of plague. The purpose of the work is to evaluate the protective effectiveness of the use of IMD of different groups in experiments on modeling infection with a highly virulent strain of the plague microbe. Materials and methods. IMD (rIFN-γ — recombinant interferon-gamma, PO — azoximer bromide, synthetic immunomodulatory oligopeptides O1, O2, O3) was administered to white mice and guinea pigs subcutaneously thrice by the schedule 3 days, 1 day, and 1 hour prior the infection with a virulent test strain of plague Yersinia pestis 231 (708) at dose from 1 to 625 CFU. In addition, the effect of IMD on the production of IFN-γ and interleukin-10 was investigated in white mice before infection. Results. The study of the effect of IMD on the survival of unvaccinated biomodels made it possible to establish that only rIFN-γ and PO increase the survival of two types of laboratory animals by 20–50% and significantly increase the LD50. All tested IMD contribute to an increase in the average life expectancy of biomodels by at least one day. An increase in spontaneous and mitogen-induced cytokine production was found only in white mice receiving rIFN-γ and PO, which correlates with animal survival rates. Conclusion. The obtained data indicate the effectiveness of the use of IMD, especially rIFN-γ and PO in protecting the macroorganisms from infection with Y. pestis, which determines the prospects for research on the further improvement of emergency prevention of plague.