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Streptococcus pneumoniae can cause many types of dangerous infectious diseases such as otitis media, pneumonia, meningitis and others that are more common in the very young and very old age. Available to date commercial vaccines based on capsular polysaccharides of S. pneumoniae of clinically important strains (first generation carbohydrate vaccines) and conjugated vaccines based on these polysaccharides (second generation carbohydrate vaccines) have certain limitations in protective efficiency. However, the efficiency of vaccines can be increased by the use of third generation vaccines based on synthetic oligosaccharide ligands representing in their structures the protective epitopes of capsular polysaccharides. The proper choice of an optimal oligosaccharide ligand is the most important step in the design of third generation carbohydrate vaccines. Herein we overview our works on the synthesis of three oligosaccharides corresponding to one, “one and a half” and two repeating units of S. pneumoniae type 14 capsular polysaccharide, immunogenic conjugates thereof and comparative immunological study of their conjugates with bovine serum albumin, which was used as a model protein carrier. The ability of obtained products to raise antibodies specific to capsular polysaccharide and homologous oligosaccharides, the induction of phagocytosis by immune antisera and active protection of immunized animals from S. pneumoniae type 14 infection were evaluated. On the basis of the results obtained tetrasaccharide comprising the repeating unit of S. pneumoniae type 14 capsular polysaccharide is an optimal carbohydrate ligand to be used as a part of the third generation carbohydrate pneumococcal vaccine.

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Background. Influenza prophylaxis with the use of quadrivalent vaccines (QIV) is increasingly being introduced into healthcare practice. Methods. In total, 32 healthy adults and 6 patients with common variable immunodeficiency (CVID) received adjuvant QIV during 2018–2019 influenza season. Depending on initial antibody titers, healthy volunteers were divided into seronegative (≤1:20) and seropositive (≥1:40). To evaluate immunogenicity hemagglutination inhibition assay was used. Results. All participants completed the study without developing serious post-vaccination reactions. Analysis of antibody titer 3 weeks after immunization in healthy participants showed that seroprotection, seroconversion levels, GMR and GMT for strains A/H1N1, A/H3N2 and B/Colorado, B/Phuket among initially seronegative and seropositive participants meet the criterion of CHMP effectiveness. CVID patients showed increase in post-vaccination antibody titer without reaching conditionally protective antibody levels. Conclusion. Adjuvant QIV promotes formation of specific immunity to vaccine strains, regardless of antibodies’ presence or absence before. In CVID patients search of new regimens should be continued.

Aim. Study subpopulation structure of lymphocytes in healthy individuals under the effect of various influenza vaccines in an in vitro system. Materials and methods. Evaluation of immunephenotype features of PBMCs, activated in vitro by immune-adjuvanted and unadjuvanted vaccines against influenza in healthy individuals, was carried out by using flow cytometry method. Results. Grippol plus vaccine caused a more pronounced stimulating effect compared with subunit and split-vaccines on NK-cells, cells with markers of early activation CD45/CD25, induced the quantity of natural regulatory cells (CD4/CD25/Foxp3), increase of the number of В-cells and reduced the amount of cell types with apoptosis marker CD45/CD95. Conclusion. Immune-adjuvanted vaccine Grippol plus induced formation of effectors of both innate and adaptive immunity and possessed the most powerful potential regarding activation of various types of immune-competent cells compared with unadjuvanted vaccines.