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Relevance. In Russia, the live plague vaccine (LPV) is used for specific prophylaxis of plague. Immunological monitoring of humans vaccinated by LPV in order to search for informative diagnostic markers, as well as to improve the tactics of epidemiological surveillance of plague enzootic territories is an urgent area of research.The aim is to assess the parameters of cellular and humoral immunity in humans revaccinated by LPV who permanently reside on territory of the Tuvinian natural plague focus.Materials and methods. The study involved 76 volunteers from the Republic of Tuva, revaccinated by LPV. Blood sampling was performed before vaccination and 1, 3, and 6 months after revaccination. The study included the determination of cytokine production (IFN-γ, IL-4, TNF-α), specific antibodies, immunoglobulins (IgM, IgG, IgA and IgE) and lymphocyte subpopulation composition (CD3, CD4, CD8, CD16, CD19, immunoregulatory index).Results. A decrease in IgG and IgM and an increase in IgA were found after vaccination with LPV and their increase after revaccination. Correlation relationships were revealed between immunoglobulins, B cells and IL-4. Revaccination leads to an increase seroconversion. The activation of humoral immunity in humans vaccinated against plague is also evidenced by dynamics of changes in the subpopulation composition: an increase in B-lymphocytes and natural killer cells, a decrease in T-helpers and immunoregulatory index, and cellular immunity stimulation is an increase in spontaneous and induced production of pro- and anti-inflammatory cytokines.Conclusion. It has been shown that LPV is capable of causing the body’s immune restructuring and activating the cellular and humoral mechanisms of immunological protection. For a complete understanding of the development and preservation of antiplague immunity, it is necessary to continue the annual immunological monitoring of the population living on the territory of the Tuvinian natural plague focus, using additional modern research methods.

Background. Plague is an especially dangerous natural focal infectious disease belonging to a group of quarantine infections. There are eleven natural plague foci in Russian Federation. In Republic Tyva plague endemic territories include Ovyur, Mongun-Taigin and Tes-Hem areas where Y. pestis strains are intermittently isolated from Citellus undulates. Population living at the territory of the natural foci get immunoprophylaxis against plague at complication of epizootic and epidemic conditions.This paper presents the results of monitoring indicators of the immune status of people vaccinated with the plague vaccine living in the territory of the Tuva natural focus.Materials and methods. The study involved 76 volunteers who had not previously been vaccinated. The study included the determination of production IFN-γ, IL-4, TNF-α by blood cells, titers of specific IgG antibodies to the capsule F1 antigen of the Yersinia pestis, and concentrations of immunoglobulins in serum blood, as well as immunophenotyping of blood lymphocytes.Results. In the course of a comprehensive immunological study, features of the development of cellular and humoral reactions in people living in the territory of the Tuva natural plague focus were established in the first months after vaccination. Changes in the concentration dynamics of the main classes of immunoglobulins were accompanied by an increase in the level of specific IgGs to the F1 within 6 months after immunization. In the same period, a significant increase in the production of cytokines, as well as significant changes in terms of the subpopulation composition of the vaccinated blood.Conclusion. It is necessary to note the importance of studying of the human immune status in 1–3 months after plague vaccination as this period coincides with potentially dangerous season from epidemiological point of view. Nevertheless, much important role for improvement of tactics of the specific prevention measures plays the data received after the revaccination.