Monoclonal antibodies (mAbs) of the IgG1 isotype obtained to the full-length recombinant pneumolysin (rPly) did not recognize or poorly recognized conformational epitopes of native pneumolysin in ELISA. At the same time, polyclonal antibodies (pAbs(rPly)) detected native pneumolysin in sandwich ELISA when they were used as capture and detecting antibodies simultaneously. All mAbs(rPly) inhibited erythrocyte hemolysis induced by native pneumolysin. The combined use of mAbs(rPly) did not reveal an increase in optical density in ELISA and an increase in inhibition hemolytic activity, which suggests that mAbs(rPly) are directed to the same or spatially closely located epitopes. pAbs(rPly) more effectively inhibited erythrocyte hemolysis than mAbs(rPly).

The species identity of the studied lactobacillus strains was confirmed by matrix-activated laser desorption/ionization with time-of-flight ion separation (MALDI-TOF mass spectrometry). Lactobacillus strains differed in the dynamics of lactic acid accumulation and changes in the pH of the culture medium. The culture medium affected adhesion ability of lactobacilli. The ability to adhere does not affect the formation of biofilms by lactobacillus strains except for the L. acidophilus La5 strain, which has low adhesion ability and fewer microbial cells detected after mechanical destruction of the biofilm. The metabiotics of the lactobacillus culture medium have an antagonistic effect on conditionally pathogenic microorganisms. Adhesion, biofilm formation, and antagonistic activity of probiotic lactobacillus strains are strain-specific properties.

Pneumolysin (Ply) is a target for the development of serotype-independent pneumococcal vaccines, an important condition for the efficacy of which is their ability to activate innate immunity with the subsequent formation of adaptive immunity. In this study, the ability of recombinant full-length Ply (rPly) of pneumococci to induce TLR expression and maturation of dendritic cells generated from mouse bone marrow was evaluated. It was shown that rPly in vitro increased the number of dendritic cells expressing Toll-like receptor 4 (TLR4) on the membrane. rPly caused maturation of dendritic cells generated from mouse bone marrow, which manifested in a decrease in the number of progenitor cells (CD34), an increase in the number of cells expressing the adhesion molecule CD38, costimulatory molecules CD80 and CD86, molecules of terminal differentiation of dendritic cells CD83, as well as molecules of antigenic presentation of the major histocompatibility complex class II.

Mucosal immunity plays a major role not only in the prevention but probably also in the outcomes of COVID-19. An enhanced production of secretory immunoglobulin A (sIgA) might contribute to the activation of the immune response mechanisms. To assess the levels of sIgA produced by epithelial cells in the nasal and pharyngeal mucosa and those measured in salivary gland secretions and to study the course of COVID-19 following the combined scheme of intranasal and subcutaneous administration of a bacteria-based immunostimulant agent. This study included 69 patients, aged between 18 and 60, who had moderate COVID-19 infection. They were divided into two groups: Group 1 (control group) included 39 patients who received only background therapy, and Group 2 was made up of 30 patients who received background therapy in combination with the Immunovac VP4 vaccine, a bacteria-based immunostimulant agent, which was given for 11 days starting from the day of admission to hospital. The levels of sIgA were measured by ELISA in epithelial, nasal and pharyngeal swabs, and salivary gland secretions at baseline and on days 14 and 30. The combined scheme of intranasal and subcutaneous administration of the Immunovac VP4 vaccine in the complex therapy of patients with COVID-19 is accompanied by increased synthesis of sIgA in nasal and pharyngeal swabs, more intense decrease in the level of C-reactive protein (CRP) and reduction in the duration of fever and length of hospitalization compared to the control group. Prescribing a immunostimulant agent containing bacterial ligands in complex therapy for COVID-19 patients helps to enhance mucosal immunity and improves the course of the disease.

The disaccharide (β-D-glucopyranosyluronic acid)-(1→4)-β-D-glucopyranoside represents a repeating unit of the capsular polysaccharide of Streptococcus pneumoniae serotype 3. A conjugate of the disaccharide with BSA (di-BSA conjugate) adjuvanted with aluminum hydroxide induced — in contrast to the non-adjuvanted conjugate — IgG1 antibody production and protected mice against S. pneumoniae serotype 3 infection after intraperitoneal prime-boost immunization. Adjuvanted and non-adjuvanted conjugates induced production of Th1 (IFNγ, TNFα); Th2 (IL-5, IL-13); Th17 (IL-17A), Th1/Th17 (IL-22), and Th2/Th17 cytokines (IL-21) after immunization. The concentration of cytokines in mice sera was higher in response to the adjuvanted conjugate, with the highest level of IL-17A production after the prime and boost immunizations. In contrast, the non-adjuvanted conjugate elicited only weak production of IL-17A, which gradually decreased after the second immunization. After boost immunization of mice with the adjuvanted di-BSA conjugate, there was a significant increase in the number of CD45+/CD19+ B cells, TCR+ γδ T cell, CD5+ В1 cells, and activated cells with MHC II+ expression in the spleens of the mice. IL-17A, TCR+ γδ T cells, and CD5+ В1 cells play a crucial role in preventing pneumococcal infection, but can also contribute to autoimmune diseases. Immunization with the adjuvanted and non-adjuvanted di-BSA conjugate did not elicit autoantibodies against double-stranded DNA targeting cell nuclei in mice. Thus, the molecular and cellular markers associated with antibody production and protective activity in response to immunization with the di-BSA conjugate adjuvanted with aluminum hydroxide are IL-17A, TCR+ γδ T cells, and CD5+ В1 cells against the background of increasing MHC II+ expression.

Background. Streptococcus pneumoniae ( S. pneumoniae , pneumococci) is an opportunistic bacterium that causes inflammatory diseases in humans. One of the virulence factors of S. pneumoniae is pneumolysin (Ply), a cholesterol-dependent hemolytic toxin that interacts with cholesterol in eukaryotic cell membranes, forms pores and leads to cell destruction and death. Aim. Immunochemical characteristics of pneumolysin and evaluation of its cytotoxic effect in the culture of Chinese hamster ovarian cells CHO-K1. Materials and methods. To obtain Ply, the S. pneumoniae serotype 3 strain was cultivated in brain heart broth, bacterial cells were pelleted by centrifugation and subjected to ultrasonic disintegration. The presence of pneumolysin in the resulting preparation was confirmed by immunoblotting with monoclonal antibodies to recombinant pneumolysin. The cytopathogenic effect of Ply was studied in a culture of proline-dependent epithelial-like Chinese hamster ovary cells CHO-K1 in RPMI-1640 medium. The hemolytic activity of Ply was assessed in a reaction with mouse erythrocytes. Results. Using ultrasonic disintegration of cells of the S. pneumoniae serotype 3 strain followed by precipitation with ammonium sulfate, a protein that formed a band on electrophoresis at a level corresponding to the molecular weight of Ply (53 kDa) was obtained. The protein possessed the ability to lyse mouse erythrocytes. The authenticity of Ply was confirmed by immunoblotting with monoclonal antibodies to recombinant pneumolysin. Ply had a cytopathogenic effect on Chinese hamster ovary CHO-K1 cells. The minimum dose of the protein that induced a toxic effect on cells, manifested in the appearance of round and small cells along with normal cells, was 16.4 μg/ml per protein. When the concentration was increased up to 65.6 μg/ml, only small round cells were detected. Further increase in concentration resulted in complete destruction of CHO-K1 cells. Conclusion. Pneumolysin can be used to develop new drugs for the treatment of pneumococcal infections.

Methylphosphorylated mono-, di- and trimannosides structurally related to the lipopolysaccharide (LPS) O-antigens of Klebsiella pneumoniae of serotype O3 were synthesized and conjugated with a biotin tag. The stereo- and regioselective assembly of target carbohydrate chains was conducted using uniform monosaccharide synthetic blocks. After that, a methylphosphate group was introduced by coupling with a methyl-H-phosphonate reagent followed by oxidation and deprotection to give the target oligosaccharides. The 1H and 13C NMR spectra of the obtained compounds showed a good fit with the spectrum of the corresponding natural polysaccharide. The newly prepared biotinylated oligosaccharides along with the previously reported biotinylated glycoconjugates related to galactan I and galactan II of K. pneumoniae LPS were used for the ELISA detection of antibodies in anti-K. pneumoniae rabbit sera. Anti-O3 serum antibodies specifically recognized the synthesized oligosaccharide ligands with terminal methylphosphomannosyl residues, whereas anti-O1 serum antibodies recognized the oligosaccharide related to K. pneumoniae galactan II. The analysis of human sera from patients with confirmed Klebsiella infection also revealed the presence of antibodies against the synthesized oligosaccharides in clinical cases. Thus, the described compounds together with other Klebsiella related antigenic oligosaccharides could be potentially used as molecular probes for K. pneumoniae serological diagnostics development and strain serotyping.

Cellular immunity plays an important role in the control of SARS-CoV-2. Lymphopenia and a decrease in the functional activity of cells may be among the main reasons for deterioration of clinical outcomes of the disease. Usage of the bacterial therapeutic vaccine Immunovac-VP-4 during the inflammation phase may be promising for immunomodulation of the cellular immunity. The aim of our study was to evaluate the dynamics of lymphocyte subpopulations in hospitalized patients with COVID-19 upon combining the basic therapy with immunotropic drug based on the antigens from opportunistic pathogens. The study included 45 patients (18-70 years old) admitted with a confirmed diagnosis of moderate/severe infection caused by the COVID-19 virus. In addition to basic therapy, 33 persons of this group received Immunovac-VP-4 by a combined nasal-oral method. Subpopulation activity of peripheral blood lymphocytes in patients over time (at baseline, on the 14th and 30th day after hospitalization) was studied by flow cytometry by means of FC-500 Cytomics (Beckman Coulter, USA) using monoclonal antibodies (mAb) (Immunotech, France). In the group receiving only standard therapy, an increased number of T lymphocytes was detected on day 14 (79.9 (75.5-81.6), p = 0.00252), on day 30 from the start of treatment (78.4 (74.25-79. 2), p = 0.03662), and a decrease in B lymphocytes on day 14 (10.6 (7.78-11.63), p = 0.03236), on day 30 (7.85 (6.25-11.1), p = 0.01352) relative to baseline parameters upon admission. We revealed more pronounced changes in the parameters of cellular immunity relative to the initial parameters, i.e., an increased proportion of T lymphocytes on the 14th day (80.1 (73.8-84.2), p = 0.00018), and 30th day from starting the treatment (80.2 (76-81.9)), T helpers at 14 days after treatment (50.2 (43-57), p = 0.00694), cytotoxic T cells by 30th day of therapy (26.35 (24-29.4), p = 0.0114), decrease in B lymphocytes on day 14 (13.1 (8.2-16.9), p = 0 00158), on the 30th day from the start of treatment (8.2 (7.6-9.7), p <0.00001), and a transient decrease in NK cells on the 14th day (3.7 (2,1-6.3), p = 0.00308), with their recovery on the 30th day of observation to 8.6 (6-12.5) in the Immunovac-VP-4 group. Modulation of cellular immunity may be important for the virus clearance.

Backgraund . Pneumolysin (Ply) is a hemolytic toxin of Streptococcus pneumoniae ( S. pneumoniae ) expressed by all strains of pneumococci. The use of sandwich enzyme-linked immunosorbent assay (ELISA) can be a simple, fast and effective way of its qualitative and quantitative determination in biological fluids. Aim. To develop and evaluate the specificity of sandwich ELISA test system for qualitative and quantitative determination of recombinant Ply (rPly) of S. pneumoniae . Materials and methods. Immobilized on the solid phase rabbit’s polyclonal antibodies (pAbs) to rPly were used as recognition antibodies in sandwich ELISA. The studied antigens were added to the pAbs (rPly). The reaction was manifested by using detecting mouse monoclonal IgG1 (rPly) – antibodies conjugated with horseradish root peroxidase. The specificity of the test system was evaluated when using recombinant α-hemolysin (rα-Hly) and water-soluble S. aureus antigens as reference preparations. Results. Using sandwich ELISA, rPly was detected at a concentration of 0.15 µ / ml. The test system was characterized by specificity, which was confirmed by the absence of reaction with recombinant rα-Hly of Staphylococcus aureus ( S. aureus ). Reference preparations of water-soluble surface antigens of S. aureus strains No 209, 1986,1991 and Cowan I gave a false positive reaction due to the presence of protein A (SpA) in their composition, a thermostable surface protein expressed by many strains of staphylococci capable of binding immunoglobulins via Fc-fragment or Fab fragments of the V3H domain of the B cells receptor. A negative reaction was obtained with antigens from the S. aureus wood 46 strain, which does not have the spa gene encoding SpA expression. The presence of protein A in preparations of water-soluble S. aureus antigens was confirmed in the ELISA inhibition assay. Conclusion. Sandwich ELISA has been developed for qualitative and quantitative determination of S. pneumoniae Ply. The conducted studies have confirmed the specificity of the test system.

Background. Experimental animal models of psoriasis helped to clarify the functions of inflammatory mediators, to reveal the contribution of innate or adaptive immune mechanisms, keratinocytes to the development and maintenance of inflammation in psoriasis. Aim. To study the subpopulation composition of immune cells of blood, skin, lymphoid organs and compare two methods of isolation of cells from the skin. Materials and methods. The study included 46 mice of the C57BL / 6 line, which were divided into 2 groups: experimental (n = 24) to reproduce a model of acute psoriasis-like dermatitis using imiquimod cream 5 % (62.5 mg / cm2 / day / mouse, 7 days) and control (n = 22). The severity of skin inflammation was assessed on a point scale. On the 7th day, the skin, spleen, lymph nodes, and thymus were examined. To isolate cells from the skin, the method of spontaneous migration and enzymatic dissociation using collagenase was used. The assessment of the subpopulation structure of mononuclear cells (MNCs) was carried out by flow cytometry using monoclonal antibodies against the corresponding antigens (CD3, CD4, CD5, CD8, MHC class II, TCRyδ, CD38, CD80, CD83, CD86, TLR2). Statistical processing was carried out using the winMDI 2.8 software package. Results. It has been shown that both methods of isolation of skin cells are applicable for immunophenotyping of γδ T-lymphocytes, CD86 + , CD83 + , CD83 + CD86 + dendritic cells. A decrease in TLR2 expression on blood cells and an increase in lymph node and skin cells were revealed. There was a marked increase in the number of CD38 + in the lymph nodes, thymus, and an increase in γδ T-lymphocytes in the lymph nodes and blood. The infiltration of γδ T-lymphocytes, CD8 + is shown in the skin and CD38 + cells. Conclusion . Acute psoriasis-like inflammation of mice was accompanied by an increase in the number of γδ T cells in the blood, lymph nodes and skin. Infiltration of the skin by CD8 + and CD38 + cells was observed. Both methods of cell isolation – the method of spontaneous migration and the method of enzymatic dissociation proved to be applicable for further immunophenotyping.

2-Aminoethyl glycoside of the pseudotetrasaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol-(5-P-2)-α-d-Galp corresponding to a repeating unit of the Streptococcus pneumoniae type 6A capsular polysaccharide has been synthesized. A suitably protected pseudotrisaccharide α-d-Glcp-(1→3)-α-l-Rhap-(1→3)-d-Rib-ol with a free 5-OH group in the ribitol moiety and a 2-OH derivative of 2-trifluoroacetamidoethyl α-d-galactopyranoside have been efficiently prepared and then connected via a phosphate bridge using the hydrogen phosphonate procedure. Preliminary immunological evaluation of this pseudotetrasaccharide and the previously synthesized pseudotetrasaccharide corresponding to a repeating unit of the capsular polysaccharide of S. pneumoniae serotype 6B has shown that they contain epitopes specifically recognized by anti-serogroup 6 antibodies and are able to model well the corresponding capsular polysaccharides. Conjugates of the synthetic pseudotetrasaccharides with bovine serum albumin were shown to be immunogenic in mice.

Streptococcus pneumoniae is a Gram-positive bacterium (pneumococcus) that causes severe diseases in adults and children. It was established that some capsular polysaccharides of the clinically significant serotypes of S. pneumoniae in the composition of commercial pneumococcal polysaccharide or conjugate vaccines exhibit low immunogenicity. The review considers production methods and structural features of the synthetic oligosaccharides from the problematic pneumococcal serotypes that are characterized with low immunogenicity due to destruction or detrimental modification occurring in the process of their preparation and purification. Bacterial serotypes that cause severe pneumococcal diseases as well as serotypes not included in the composition of the pneumococcal conjugate vaccines are also discussed. It is demonstrated that the synthetic oligosaccharides corresponding to protective glycotopes of the capsular polysaccharides of various pneumococcal serotypes are capable of inducing formation of the protective opsonizing antibodies and immunological memory. Optimal constructs of oligosaccharides from the epidemiologically significant pneumococcal serotypes are presented that can be used for designing synthetic pneumococcal vaccines, as well as test systems for diagnosis of S. pneumoniae infections and monitoring of vaccination efficiency .

A number of studies have demonstrated the limited efficacy of S. pneumoniae type 3 capsular polysaccharide (CP) in the 13-valent pneumococcal conjugate vaccine against serotype 3 invasive pneumococcal diseases and carriage. Synthetic oligosaccharides (OSs) may provide an alternative to CPs for development of novel conjugated pneumococcal vaccines and diagnostic test systems. A comparative immunological study of di–, tri–, and tetra–bovine serum albumin (BSA) conjugates was performed. All oligosaccharides conjugated with biotin and immobilized on streptavidin-coated plates stimulated production of IL-1 α , IL-2, IL-4, IL-5, IL-10, IFN γ , IL-17A, and TNFα, but not IL-6 and GM-CSF in monocultured mice splenocytes. The tetrasaccharide–biotin conjugate stimulated the highest levels of IL-4, IL-5, IL-10, and IFN γ , which regulate expression of specific immunoglobulin isotypes. The tetra–BSA conjugate adjuvanted with aluminum hydroxide elicited high levels of IgM, IgG1, IgG2a, and IgG2b antibodies (Abs). Anti-CP-induced Abs could only be measured using the biotinylated tetrasaccharide. The tetrasaccharide ligand possessed the highest binding capacity for anti-OS and antibacterial IgG Abs in immune sera. Sera to the tetra–BSA conjugate promoted greater phagocytosis of bacteria by neutrophils and monocytes than the CRM 197 -CP-antisera. Sera of mice immunized with the tetra–BSA conjugate exhibited the highest titer of anti-CP IgG1 Abs compared with sera of mice inoculated with the same doses of di– and tri–BSA conjugates. Upon intraperitoneal challenge with lethal doses of S. pneumoniae type 3, the tri– and tetra–BSA conjugates protected mice more significantly than the di–BSA conjugate. Therefore, it may be concluded that the tetrasaccharide ligand is an optimal candidate for development of a semi-synthetic vaccine against S. pneumoniae type 3 and diagnostic test systems.

Relevance. Prevention of pneumococcal infection in the Russian Federation is carried out by imported polysaccharide and conjugated vaccines without taking into account the circulation of clinically significant isolates, which leads to the growth of previously rare genetic lines and serotypes that are not part of the vaccines, and does not protect against the carriage. Serotype-independent vaccines are being developed based on protective proteins and variants of whole-cell vaccines capable of providing a cross-protective effect against pneumococcus. Objective. Investigation of the protective properties of surface protein-containing antigens isolated from the immunogenic strain S. pneumoniae 6B No. 296 and their influence on key effectors of innate immunity. Materials and methods. S. pneumoniae 6B No. 296 was cultured in a semi-synthetic medium under stationary conditions at 5% CO2 for 5-7 hours. From inactivated bacterial cells, the experimental initial protein-containing preparation was obtained - an aqueous extract (A/E), from which a 30-100 kDa fraction (FR) isolated, and from the sterile culture supernatant, the protein-containing preparation - supernatant (S/N); in the preparations, the protein content was determined. Immunobiological properties were studied after double intraperitoneal immunization of BALB/c mice. The protective activity was determined after infection with virulent strains of S. pneumoniae serotypes 6B No. 1121 and No. 3. Phagocytic activity was studied by the number of granulocytes that absorbed heat-killed FITC-labeled S. aureus cells. The expression of Toll-like receptors (TLRs) and the subpopulation structure of mouse spleen lymphocytes were investigated after staining with FITC/PE-labeled monoclonal antibodies using flow cytometry. Statistical analysis of materials was carried out using parametric and non-parametric methods using the software package «Statistica for Windows», ver. 7.0 (Stat Soft, Inc). Results. The protective effect of FR upon infection with virulent strains of homologous (6B No. 1121) and heterologous serotypes (3 No. 3) was established; S/N protected mice when infected with strain 3 No. 3. All the studied drugs led to an increase in the number of phagocytic cells (the greatest effect was observed upon immunization with FR and S/N) and stimulated the expression of TLR2 and TLR4 positive cells (there was an increase in the number of TLR2-expressing cells during immunization with FR compared with A/E). When studying the immunophenotype of mouse lymphocytes, it was noted that the preparations induced the expression of effectors of innate and adaptive immunity. Conclusions. As a result of the studies, it was shown that the protective surface protein-containing fraction with MM 30-100 kDa is from tested experimental preparations the most active stimulator of innate and adaptive immunity, and requires further study to determine the possibility of using the serotype-independent pneumococcal vaccine in the development.

Relevance. Vaccines based on capsular polysaccharides of pneumococci are not active against serotypes that are not included in the vaccine, non-capsulated strains and do not protect against carriage caused by other serotypes. Their use leads to the replacement of dominant serotypes of pneumococci, the appearance of highly virulent strains, changes in the microbial landscape of mucous membranes due to the appearance of other etiologically significant pathogens of respiratory tract diseases. This requires the creation of intraspecific anti-pneumococcal immunity, which will be facilitated by the development of serotype-dependent drugs, which will include protein-containing antigens of pneumococci. Objective. Study of serotype-independent activity of protein-containing antigenic components obtained from freshly isolated and archival strains of S. pneumoniae. Materials and methods. Strains of three serotypes of S. pneumoniae were used: archival strains of serotypes 6B N296, 19F N 298 and 10A N297 and freshly isolated serotypes 6B N 1121, 19F N 1055 and serogroup 10 N 1193 (from the cerebrospinal fluid of patients with purulent meningitis).. In the experimental protein-containing preparations EPCP obtained, the protein content was determined. Protective activity of EPCP and virulence of strains were determined in the model of intraperitoneal immunization and infection of BALB/c mice; LD50 was calculated using the generally accepted modified Kerber formula. The immunophenotype of lymphocytes previously isolated from donor-mice whole blood was studied by flow cytometry. Statistical analysis of the materials was carried out using parametric and nonparametric methods using the application package «Statistica for Windows», ver. 7.0 (Stat Soft, Inc); in statistical analysis, the significance level of p was assumed to be < 0.05. Results and discussion. During cultivation there was the analysis of growth dynamics showed intensive accumulation of biomass of the archival strain N296 with low virulence, and lower - by virulent strain N 1121 isolated from the patient's cerebrospinal fluid. The protein content of drugs from serotype 6B strains did not differ. The strains of other serotypes isolated during the generalized infectious process were also more virulent than the archival strain. The effect on the immunophenotype of human lymphocytes of fractions of 50-100 kDa isolated from the initial preparations obtained by culturing serotype 6B, significantly increased only under the influence of the preparation from the archival strain. In the study of protective activity of the initial preparations from strains of serotype 6B and fractions with MM 50-100 kDa only triple immunization with the initial preparation from strain N 296, at a dose of 20 micrograms of protein per mouse, led to significantly greater survival of immunized mice from infection with the newly isolated virulent strain N 1121 of homologous serotype. A fraction of 30-100 kDa provided protection of mice twice immunized with 50 mkg of protein per mouse, with a high efficacy index of 8.9, even after infection with a freshly isolated strain of heterologous S. pneumoniae serotype 3 N 10196. Conclusion. The protein-containing fraction with MM 30-100 kDa obtained from a low virulent archival strain of S. pneumoniae serotype 6B N296 possessed protective activity against a newly isolated virulent strain of heterologous serotype after double immunization. Under the action of the studied protein-containing fractions, activation of the cellular component of immune system with the involvement of innate immunity effectors and T-lymphocytes is shown. These data can be considered as a evidence for further study of EPCP to assess the possibility of their use in the design of anti-pneumococcal drug with serotype-independent protective activity.

The introduction of pneumococcal vaccines into national immunization programmes around the world has reduced the incidence of pneumococcal vaccine serotypes, but had no influence on the incidence of Streptococcus pneumoniae serotype 3 included in their composition. The results of evaluation of epidemiological efficacy and immunogenicity of capsular polysaccharide of S. pneumoniae serotype 3 capsular polysaccharide (CP) in conjugated and polysaccharide pneumococcal vaccines are contradictory. Some studies have shown the effectiveness of vaccination, other studies indicate insufficient immunogenicity and prophylactic efficacy of S. pneumoniae serotype 3 CP. The authors’ analysis of the results of clinical studies showed that the prophylactic efficacy of S. pneumoniae serotype 3 CP depends on the type of vaccine, nosological form of the disease, age, immunization schedule. According to the literature data, the most informative parameter of the protective activity of S. pneumoniae CP in pneumococcal vaccines, including serotype 3, is opsonophagocytosis. The experimental data of the low immunogenicity of serotype 3 CP, presumably associated with an unusual way of synthesis of its CP, are considered. To increase the im muno genicity of S. pneumoniae serotype 3 CP, the use of synthetic oligosaccharides of a strictly defined chemical structure corresponding to the protective fragments of serotype 3 CP and conjugated with a carrier protein for induction of T-dependent immune response and immunological memory is promising.

Relevance. Vaccines based on capsular polysaccharides of pneumococci are not active against serotypes that are not included in the vaccine, non-capsulated strains and do not protect against carriage caused by other serotypes. Their use leads to the replacement of dominant serotypes of pneumococci, the appearance of highly virulent strains, changes in the microbial landscape of mucous membranes due to the appearance of other etiologically significant pathogens of respiratory tract diseases. This requires the creation of intraspecific anti-pneumococcal immunity, which will be facilitated by the development of serotype-dependent drugs, which will include protein-containing antigens of pneumococci.Objective. Study of serotype-independent activity of protein-containing antigenic components obtained from freshly isolated and archival strains of S. pneumoniae.Materials and methods. Strains of three serotypes of S. pneumoniae were used: archival strains of serotypes 6B N296, 19F N 298 and 10A N297 and freshly isolated serotypes 6B N 1121, 19F N 1055 and serogroup 10 N 1193 (from the cerebrospinal fluid of patients with purulent meningitis).. In the experimental protein-containing preparations EPCP obtained, the protein content was determined. Protective activity of EPCP and virulence of strains were determined in the model of intraperitoneal immunization and infection of BALB/c mice; LD50 was calculated using the generally accepted modified Kerber formula. The immunophenotype of lymphocytes previously isolated from donor-mice whole blood was studied by flow cytometry. Statistical analysis of the materials was carried out using parametric and nonparametric methods using the application package «Statistica for Windows», ver. 7.0 (Stat Soft, Inc); in statistical analysis, the significance level of p was assumed to be < 0.05.Results and discussion. During cultivation there was the analysis of growth dynamics showed intensive accumulation of biomass of the archival strain N296 with low virulence, and lower - by virulent strain N 1121 isolated from the patient's cerebrospinal fluid. The protein content of drugs from serotype 6B strains did not differ. The strains of other serotypes isolated during the generalized infectious process were also more virulent than the archival strain. The effect on the immunophenotype of human lymphocytes of fractions of 50-100 kDa isolated from the initial preparations obtained by culturing serotype 6B, significantly increased only under the influence of the preparation from the archival strain. In the study of protective activity of the initial preparations from strains of serotype 6B and fractions with MM 50-100 kDa only triple immunization with the initial preparation from strain N 296, at a dose of 20 micrograms of protein per mouse, led to significantly greater survival of immunized mice from infection with the newly isolated virulent strain N 1121 of homologous serotype. A fraction of 30-100 kDa provided protection of mice twice immunized with 50 mkg of protein per mouse, with a high efficacy index of 8.9, even after infection with a freshly isolated strain of heterologous S. pneumoniae serotype 3 N 10196.Conclusion. The protein-containing fraction with MM 30-100 kDa obtained from a low virulent archival strain of S. pneumoniae serotype 6B N296 possessed protective activity against a newly isolated virulent strain of heterologous serotype after double immunization. Under the action of the studied protein-containing fractions, activation of the cellular component of immune system with the involvement of innate immunity effectors and T-lymphocytes is shown. These data can be considered as a evidence for further study of EPCP to assess the possibility of their use in the design of anti-pneumococcal drug with serotype-independent protective activity.

Klebsiella pneumoniae Is a Gram-negative pathogenic bacterium that emerges a challenge for modern medicine due to intensively rising multi-drug resistance. Specific LPS O-chains represent promising targets for development of vaccines for immunoprophylaxis or immunotherapy of K. pneumoniae-caused diseases. Herein, the synthesis of di-, tetra-, and hexasaccharides which represent structural fragments of both galactan I and galactan II of K. pneumoniae LPS O-chains is described. The galactofuranoside building block used for assembling the galactan I chains was prepared by pyranoside-into-furanoside (PIF) rearrangement of the corresponding galactopyranoside precursor bearing an acid-labile temporary p-methoxybenzyl protecting group at O(3). The synthesized set of K. pneumoniae antigenic oligosaccharides in the form of their biotinylated derivatives was used to create a glycoarray which was applied for the screening of antibodies to galactan I and galactan II in anti-K. pneumoniae sera. The obtained results demonstrate the applicability of such a glycoarray-based assay for typing antibodies to Klebsiella strains belonging to most frequent O1 serogroup.