Increasing the immunogenic and protective activity of the vaccine strain Yersinia pestis EV line NIIEG using synthetic immunomodulators

Abstract

Introduction. One of the main tasks of specific plague prevention remains the development of vaccines and their application schemes aimed at improving the effectiveness of vaccination through the use of adjuvants and immunomodulators. The purpose of the study were comparative evaluation of the effect of drugs from the group of synthetic immunomodulators on the immunogenic and protective properties of the Yersinia pestis EV line NIIEG vaccine strain in model animal experiments. Materials and methods. White mice and guinea pigs were immunized with the vaccine strain Y. pestis EV line NIIEG. The animals of the experimental groups were injected with oligopeptides O1 (Threonyl-glutamyl-lysyl-lysyl-arginyl-arginyl-glutamyl-threonyl-valyl-glutamyl-arginyl-glutamyl-lysyl-glutamate), O2 (Glutamyl-cysteinyl-glycine disodium) and O3 (Arginyl-alpha-aspartyl-lysyl-valyl-tyrosyl-arginine) one hour before vaccination or three times before infection. On days 3, 14 and 21, antibody and cytokine products were studied. Animals were infected with the test strain Y. pestis 231(708) at a dose of 400 LD50. Results. It was found that a single administration of immunomodulators 1 hour before vaccination did not change the susceptibility of animals to the plague microbe: ImD50 = 5860 (O1); 5860 (O2); 6454 (O3) and 6876 (control) CFU for white mice and 446 (O1), 551 (O2), 446 (O3) and 578 (control) CFU for guinea pigs. Three-time administration of drugs to vaccinated animals led to a decrease in the ImD50 Y. pestis EV line NIIEG indicators in the group with O1 by 2.2 times (mice) and 1.8 times (guinea pigs), with O2 and O3 by 1.2 times, regardless of the biomodel compared with the control. The stimulating effect of O1 and O3 on the production of antibodies to F1 of the plague microbe and cytokines interferon-gamma, interleukin-10 has been established. Conclusion. The stimulating potential of synthetic immunomodulators on the immune system of biomodels immunized by Y. pestis EV line NIIEG has been demonstrated, which determines the prospects of research to improve the schemes of prophylactic vaccination against plague.