T. V. Gapel’CHenkova

Animal-model studies used to predict vaccine efficacy in humans are challenging because direct extrapolation of experimental results to humans is not possible for a number of reasons. Interspecies differences in pathogen-recognition receptors may explain differences between humans and rodents in the response to microbial vaccines. There are also species-specific B-cell and T-cell repertoires, as well as HLA presentation of dominant epitopes to CD4 and CD8 T cells. Because of these limitations, studies of candidate vaccines are conducted in several species of small and large animals, which is expected to yield data more transferable to humans. The aim of this study was a comparative assessment in mice and guinea pigs of the protective effect of the differing in antigenic composition 231ΔnlpD and EVΔlpxM plague pathogen strains upon a single immunization with them separately or in a mixture. Materials and methods. The protectivity of the studied strains was characterized by the immunity index in subcutaneous infection of mice and guinea pigs. Results. As in previous experiments [1], the introduction of monopreparations based on attenuated 231ΔnlpD or EVΔlpxM strains selectively induced protection only in mice or guinea pigs, respectively. Immunization with a mixture of attenuated strains provided an immunity index of more than 108 for both types of laboratory animals. Conclusion. Single-stage subcutaneous immunization of mice and guinea pigs with attenuated Y. pestis strains 231ΔnlpD and EVΔlpxM enhances immunity to plague following subcutaneous challenge with wild-type strain 231.

The goal of this study is to find out the effect of deletion of some genes encoding biogenesis of components of the outer membrane protein complex on the virulence of Yersinia pseudotuberculosis mutants. Materials and methods. Y. pseudotuberculosis surA, degP, bamB, and ompH mutants were generated by RedGam mutagenesis using suicide vectors. The constructed mutants were characterized by growth rate, sensitivity to antibiotics, bile salts, and sodium dodecyl sulfate, as well as to the bactericidal action of normal human serum. Total composition of the outer membrane proteins of the knockout mutants was determined by SDS-PAGE. The virulence of DsurA, DdegP, DbamB and DompH was studied after subcutaneous, intraperitoneal, or oral infection of mice. Results. It was found that BamB, OmpH and SurA proteins were necessary for maintaining the integrity of the Y. pseudotuberculosis cell membrane, SurA and BamB proteins are important for resistance to the bactericidal action of serum complement and a high degree of attenuation of Y. pseudotuberculosis strains with deleted surA, degP, bamB genes for outbred mice was revealed. Conclusion. The surA, degP, and bamB genes can be used as potential molecular targets for construction of Y. pseudotuberculosis vaccine strains.

Animal model studies used to predict vaccine efficacy in humans present a considerable challenge, as direct extrapolation of experimental results to humans

The goal of this study is to identify the effect of deletion of some genes encoding biogenesis of outer membrane protein complex components on the virulenc

The aim of this work was to determine the role of periplasmic chaperone SurA in the pathogenesis of bubonic and pneumonic plague. Yersinia pestis surA knoc

Goal. Determination of the role of periplasmic chaperone SurA in the pathogenesis of bubonic and pneumonic plague. MATERIALS AND METHODS Yersinia pestis surA knockout mutants were generated by RedGam mutagenesis with the use of a suicide vector. The generated strains were characterized by their growth rate, sensitivity to antibiotics, bile acid salts and sodium dodecyl sulfate, as well as to the bactericidal action of normal human serum. Intracellular localization of the SurA protein was determined by DSN-PAAG and immunoblot methods. The virulence of the ΔsurA mutant was studied in subcutaneously or intranasally infected mice or rats. RESULTS The SurA-negative Y. pestis strain was characterized by an increase in the permeability of the outer membrane and sensitivity to antibiotics, as well as a decrease in virulence in a model of bubonic and pneumonic plague in two laboratory animal species. CONCLUSION The SurA protein can be considered as a molecular target for plague therapy. Reducing the virulence of a strain and its resistance to antibiotics by disrupting the biogenesis of outer membrane proteins may become a new strategy for solving the problem of combating multidrug resistance, and the widespread distribution of the protein among Gram-negative pathogens makes its use promising for the development of virulence inhibitors with a broad spectrum of action.

Designing of new means for the specific prevention of plague, especially protein subunit vaccines, is impossible without studying the role of individual antigens in the manifestation of the pathogenic and immunogenic properties of Yersinia pestis. The aim of the present study was to determine the antibody levels to Y. pestis antigens in guinea pigs that survived infection with sub-lethal doses of virulent plague agent strains using enzyme immunoassay (ELISA). Materials and methods. Guinea pigs were inoculated subcutaneously with 30 CFU of the wild type Y. pestis subsp. Pestis strain 231 or non-capsular Y. pestis subsp. pestis Caf1-negative strain 358/12. Blood samples from sick or recovered guinea pigs were collected on day 15, 30, 60, and 90 after infection. The antibody response was assessed by 18 recombinant Y. pestis proteins in ELISA. Results and discussion. Heterogeneity of the antibody responses to the majority of the antigens with variation of IgG titers from animal to animal has been revealed. We observed increase in antibody titers by day 90 for the most analyzed antigens in the sera of the guinea pigs injected with wild type Y. pestis 231. On the contrary we found reduction in antibody titers by day 90 in case of inoculation with Y. pestis 358/12. The preservation of antibodies to Y. pestis proteins of different localization in the organism of the guinea pigs, as well functional activity, and the degree of representation on the surface of bacterial cell for a prolonged period of time indicates the multiplex nature of the plague immunity formation. Our findings are significant for the future design and development of effective vaccines against plague and the search for new targets for diagnostics of this disease.