Experience of Using a Complex Antigenic Preparation of the Plague Microbe to Assess the Severity of a Specific Anti-Plague Response

Background. Improving the methodology of immunological monitoring in natural foci of plague in the Russian Federation and adjacent territories to increase the effectiveness of epidemiological surveillance of plague is an urgent line of research. The lack of correlation between the production of specific antibodies to the capsular antigen (F1) ofthe plague microbe with other indicators of the state of cellular defense reactivity indicates the need to search for new informative and accessible markers for assessing anti-plague immunity.Objective: to evaluate possibility of using the complex preparation (F1 and cell membranes) evaluate the possibilities of using an artificial antigenic complex based on F1 and cell membranes (CM) of the plague microbe in antigen-specific tests in vitro in people vaccinated against plague.resu. The study involved 153 volunteers living in the territory enzootic for plague (the village of Khandagayty ofthe Ovyur kozhuun of the Tyva Republic and the village of Kosh-Agach of the Kosh-Agach district of the Altai Republic). The study included the determination of spontaneous and mitogen-induced production of cytokines (IFN-γ, IL-4, TNF-α) by blood cells, titers of specific IgG antibodies to the capsular antigen F1 of the plague microbe and concentrations ofthe main classes of immunoglobulins (IgM, IgG, IgA and IgE) in blood serum, as well as immunophenotyping of blood lymphocytes (CD3, CD4, CD8, CD16, CD19).Results. Comparative assessment of the level of cytokines (TNF-α, IFN-γ and IL-4) in spontaneous/induced F1+CM Y. pestis tests revealed a statistically significant increase in the production of cytokines TNF-α and IFN-γ in the antigeninduced tests compared with spontaneous (p < 0.01).Conclusion. Thus, the effectiveness of the use of artificial antigenic complex based on F1 and cell membranes ofthe plague microbe has been shown to assess the production of cytokines in antigen-specific cell tests in vitro, which justifies the need for further research.

An extraordinary case of oral leukocytoclastic vasculitis demonstrating igd deposition around dermal vessels and within mucosal keratinocytes

Cutaneous vasculitides include a widespread and heterogeneous cluster of diseases affecting the blood vessels that are clinically characterized by polymorphic skin lesions, including palpable purpura, urticarial and/or necrotic-ulcerative lesions. Often, they can be manifestations of a systemic disease. Selected cases occur in the mouth. A 75-year-old female presented to her physician for the sudden appearance of blisters in her mouth, with severe orodynia and no history of other diseases or medication intake. A skin biopsy of the oral mucosa yielded a diagnosis of leukocytoclastic vasculitis. The direct immunofluorescence and immunohistochemistry stains demonstrated deposits of IgD, IgG, IgA, IgM, kappa, lambda, C1q, C3c, albumin and fibrinogen at the upper dermal neurovascular plexus. IgD also demonstrated positive nucleolar staining of the keratinocytes. Our case involves a rare presentation of oral cutaneous vasculitis with immune deposits of several immunoglobulins, complement, albumin and fibrinogen. Our case adds importance to studies of the IgD role in antigenic complex immune responses, especially in the mouth.

Platelet-Derived Microparticles Bearing PF4 and Anti-GAGS Immunoglobulins in Patients with Sepsis

PF4 is a megakaryocyte-derived cationic chemokine that plays a part in innate immunity through its activity on the macrophages. In bacterial sepsis, PF4 binds to glycosaminoglycans (GAGs) on the surface of aerobic bacteria, giving rise to an antigenic complex that induces the early formation of anti-PF4 IgG-IgA-IgM. This triggers the immune response in patients receiving heparin therapy who develop heparin-induced thrombocytopenia (HIT). These antibodies have also been identified in patients with chronic Gram-negative infections. Given the complexity of this innate immune response network, our study on 45 patients with sepsis focused on the immune response mediated by platelet PF4. We analyzed the role of IgG-IgA-IgM against PF4-GAGs, and the presence of specific PF4-bearing platelet microparticles (PMPs). Anti-GAGs/PF4 IgG-IgA-IgM levels were significantly higher in septic patients than in control groups (healthy controls or acute patients without sepsis, p < 0.001). PF4-bearing PMP levels were only significantly higher in septic patients (p < 0.001). The occurrence of IgG-IgA-IgM against PF4-GAGs and PF4+ PMPs correlated with an improvement in patients’ sepsis. In conclusion, we demonstrated that, in the course of bacterial sepsis, platelet activation leads to the formation of specific PF4-bearing PMPs. These specific microparticles bind to polyanionic sequences on the surface of aerobic bacteria, giving rise to an antigenic complex that induces the early formation of IgG-IgA-IgM against PF4-GAGs as an innate immune response to infection.

Arthritogenic Alphavirus Vaccines: Serogrouping Versus Cross-Protection in Mouse Models

Chikungunya virus (CHIKV), Ross River virus (RRV), o’nyong nyong virus (ONNV), Mayaro virus (MAYV) and Getah virus (GETV) represent arthritogenic alphaviruses belonging to the Semliki Forest virus antigenic complex. Antibodies raised against one of these viruses can cross-react with other serogroup members, suggesting that, for instance, a CHIKV vaccine (deemed commercially viable) might provide cross-protection against antigenically related alphaviruses. Herein we use human alphavirus isolates (including a new human RRV isolate) and wild-type mice to explore whether infection with one virus leads to cross-protection against viremia after challenge with other members of the antigenic complex. Persistently infected Rag1-/- mice were also used to assess the cross-protective capacity of convalescent CHIKV serum. We also assessed the ability of a recombinant poxvirus-based CHIKV vaccine and a commercially available formalin-fixed, whole-virus GETV vaccine to induce cross-protective responses. Although cross-protection and/or cross-reactivity were clearly evident, they were not universal and were often suboptimal. Even for the more closely related viruses (e.g., CHIKV and ONNV, or RRV and GETV), vaccine-mediated neutralization and/or protection against the intended homologous target was significantly more effective than cross-neutralization and/or cross-protection against the heterologous virus. Effective vaccine-mediated cross-protection would thus likely require a higher dose and/or more vaccinations, which is likely to be unattractive to regulators and vaccine manufacturers.

Proregenerative Activity of IL-33 in Gastric Tissue Cells Undergoing Helicobacter Pylori-Induced Apoptosis

Interleukin (IL)-33 is a proinflammatory mediator that alerts the host immune system to disorders in tissue homeostasis. Aim. To understand the role of IL-33 in modulating gastric tissue cell growth affected by Helicobacter pylori (H. pylori). Methods. IL-33 production in guinea pigs (Caviae porcellus) experimentally infected with H. pylori was evaluated by ELISA or immunohistochemical staining. The proregenerative activity of IL-33 was evaluated using gastric epithelial cells and fibroblasts that were naive or transfected with IL-33 siRNA exposed to H. pylori glycine acid extract antigenic complex (GE), as well as by measuring cell migration, proliferation, metabolic activity and apoptosis. Animals infected by H. pylori responded with increased production of IL-33. Also, cells treated in vitro with GE released more IL-33 than cells that were unstimulated. Silencing IL-33 in cells resulted in downregulation of metabolic activity, adhesion, migration and proliferation, especially after treatment with H. pylori GE, as well as upregulation of cells apoptosis associated with caspase 3 increase and Bcl-xL decrease, suggesting proregenerative activity of IL-33. Interestingly, upregulation of cell proliferation by IL-33 was Erk independent. Our results indicate that IL-33 may protect gastric tissue from loss of homeostasis caused by deleterious effects of H. pylori components and the inflammatory response developed during infection.

STUDYING DEVELOPMENT OF POST-VACCINAL CELLULAR IMMUNITY AGAINST BRUCELLOSIS BY MEANS OF LYMPHOCYTE IN VITRO TESTS USING AN EXPERIMENTAL ANTIGENIC COMPLEX

Regulatory framework and methodological approaches to evaluation of immunological effects of vaccination against brucellosis are not established, and the degree of immunological post-vaccinal rearrangement is not yet developed. Due to leading role of cellular immunity in formation of immune protection against brucellosis, evaluation the cellular response in response to antigenic stimulation may be considered the most informative and objective approach to analysis of immune changes in the body during vaccination. In order to develop the most diagnostically informative methods for design of antigen-stimulation cell tests in vitro, a careful selection of a stimulating agent (antigen) is required, which should have a sufficient activating potential, thus providing specificity of reaction under in vitro conditions. The aim of the present study is to study the in vitro specific activity of a protein-polysaccharide antigenic complex from the Brucella abortus 19 BA strain (BrAg), and an opportunity of its application in order to assess the formation of post-vaccinal cellular immunity against brucellosis.The study was performed with white laboratory mice (n = 50) immunized with the Brucella abortus 19 BA strain. The control group (n = 50) consisted of laboratory mice that received a sterile saline solution in a volume of 0.5 ml. Blood samples were taken from immunized and control animals before vaccination, and 7, 14, 21, and 30 days after immunization. By means of flow cytometry, the activation molecules CD25, CD69, MHC II and CD95, expressed on T lymphocytes (CD3+CD69+, CD3+CD25+, CD3+CD95+, CD3+MHC+) were determined. To observe the development of immunity, the intensity of expression of T lymphocyte activation markers was calculated using the stimulation quotient. BrAg was used for specific in vitro stimulation of T lymphocytes. The liquid brucellosis allergen (brucellin) was used as an antigen for comparison, when studying opportunity of BrAg usage for assessing the postvaccinal immunity development.The following results were obtained: BrAg has pronounced specific activity, it did not cause non-specific in vitro reactions (activation) of T lymphocytes, thus enabling its application as a test antigen when evaluating development of adaptive vaccine immunity against brucella.Experimental testing of brucellosis antigen for carrying out the in vitro antigen-stimulated cellular reactions, aiming for evaluation of post-vaccinal immunity development against brucellosis, showed that the usage of BrAg promotes increase in diagnostic sensitivity of cellular reactions under in vitro experimental conditions. The applied experimental antigen is a quite promising tool for development of laboratory algorithms for brucellosis diagnostics, and assessment of actual vaccination efficiency in cohorts previously vaccinated against brucellosis.

Complex Bfr-O-Antigen of Francisella tularensis Outer Membranes: Production, Characteristics and Potential Use

A method for the isolation of a complex antigen of protein-carbohydrate nature from outer membranes of the vaccine strain Francisella tularensis subsp. holarctica 15 NIIEG cells and its detailed characteristics have been described. A protein of bacterioferritin (Bfr) and O-antigen were identified in the antigenic complex. It was shown that the obtained complex antigen is non-toxic, harmless, has high immunogenic activity and protects white mice in the subcutaneous infection with a virulent strain of F. tularensis subsp. holarctica 503/840. This antigen was shown to occur in the tularemia microbe regardless of the subspecies and presence of a capsule. The high antigenic and immunobiological activity of the Bfr-O-antigen complex provides the prerequisites for its further use as a component in the development of preventive and diagnostic drugs against the tularemia infection. Francisella tularensis, antigens, outer membrane proteins, immunogenicity, lipopoly saccharide, O-antigen. Authors would like to thank to the staff of the Institute «Microbe»: laboratory of molecular diagnostics I.V. Terekhova for providing us with the monoclonal antibodies, laboratories for genomic and proteomic analysis N.V. Kotova for her excellent technical assistance.