Fatima M. Izhaeva

Introduction. Mycoses (fungal infections) represent a serious global health threat: more than 6.5 million severe invasive cases of such diseases are registered annually worldwide, accompanied by extremely high mortality (on average 68%). The high degree of threat determines the relevance of intensifying research into the mechanisms of fungal drug resistance, the pathogenesis of the fungal diseases, as well as the development of more effective therapeutic approaches. The implementation of methods that combine high analysis speed with accurate quantitative assessment of viable microorganisms is a key condition for obtaining reproducible research results both at the stage of culture preparation for in vivo infection modeling and when evaluating the efficacy of antifungal drugs. Aim of this study was to develop and evaluate the application of flow cytometry for rapid quantification of microorganisms using Candida albicans fungi as an example, both in pure culture and in multicomponent samples, in comparison with the CFU counting method. Materials and Methods. To model infection, female BALB/c mice were intravenously inoculated with C. albicans isolate GIMC100:CaMK2014SRP at doses of 0.5 × 10⁶, 1.0 × 10⁶, and 2.0 × 10⁶ CFU/animal. The number and viability of C. albicans cells were assessed by culture-based and flow cytometric methods using species-specific FITC-labeled antibodies and propidium iodide. Results. Flow cytometry allows rapid counting of C. albicans in samples, showing measurement accuracy comparable to the CFU counting method across a wide range of pathogen concentrations (from 100 to 1 million cells). The use of pathogen-specific fluorescently labeled antibodies and a viability dye makes it possible to reliably detect live C. albicans cells in samples regardless of the presence of impurities (debris, eukaryotic cells, dead C. albicans cells), without reducing counting accuracy. Conclusion. Having no alternatives with similar characteristics, the proposed method appears to be highly demanded for the standardization of C. albicans samples for modeling candidiasis in laboratory animals. Furthermore, this method is seen as a promising alternative to the conventional method of CFU counting on solid nutrient media for determining the number of live C. albicans cells when analyzing biological samples or evaluating the efficacy of antifungal drugs in culture.

Background/Objectives: Tuberculosis (TB) remains the leading cause of death from a single infectious agent worldwide. In line with the World Health Organization’s (WHO) goal to end TB by 2035, the rapid development and clinical implementation of new, effective vaccines is urgently needed. To support global TB control efforts, we developed a novel candidate subunit multistage vaccine. Methods: This vaccine incorporates multiple Mycobacterium tuberculosis antigens expressed during both dormant and active stages of infection, fused into a single recombinant protein (ESAT6-CFP10-Ag85A-Rv2660c-Rv1813c). The antigen was encapsulated in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles along with the pattern recognition receptor (PRR) agonists monophosphoryl lipid A (MPLA) and muramyl dipeptide (MDP), which function as adjuvants. Results: Using a mixed intramuscular/nasal prime-boost regimen, the vaccine elicited a mixed Th1/Th17 cell-mediated immune response, as well as a robust humoral response characterized by sustained systemic IgG (lasting at least one year) and prominent local secretory IgA. The vaccine demonstrated protective efficacy as a prophylactic booster following BCG priming in both murine and guinea pig models and was also effective in a therapeutic setting in a murine infection model. Conclusions: The results of this study provide empirical evidence that multistage tuberculosis vaccines represent a promising strategy for achieving global TB control.

Background: The SARS-CoV-2 virus continuously acquires mutations, leading to the emergence of new variants. Notably, the effectiveness of global vaccination efforts has significantly declined with the rise and spread of the B.1.1.529 (Omicron) variant. Methods: The study used virological, immunological and histological research methods, as well as methods of working with laboratory animals. In this study, we evaluated the Gam-COVID-Vac (Sputnik V), an adenoviral vaccine developed by the N.F. Gamaleya National Research Center for Epidemiology and Microbiology, and conducted experiments on hemizygous K18-ACE2-transgenic F1 mice. The variants studied included B.1.1.1, B.1.1.7, B.1.351, B.1.1.28/P.1, B.1.617.2, and B.1.1.529 BA.5. Results: Our findings demonstrate that the Sputnik V vaccine elicits a robust humoral and cellular immune response, effectively protecting vaccinated animals from challenges posed by various SARS-CoV-2 variants. However, we observed a notable reduction in vaccine efficacy against the B.1.1.529 (Omicron BA.5) variant. Conclusions: Our results indicate that ongoing monitoring of emerging mutations is crucial to assess vaccine efficacy against new SARS-CoV-2 variants to identify those with pandemic potential. If protective efficacy declines, it will be imperative to develop new vaccines tailored to current variants of the virus.

Ebola virus disease (EVD) is one of the most dangerous and lethal diseases affecting humans. There are several licensed vaccines against EVD, but it remains one of the priority diseases for research and development of effective vaccines. A double-blind randomized placebo-controlled trial was performed to evaluate safety and immunogenicity of rVSV- and rAd5-vectored vaccine “GamEvac-Combi” in healthy adults of both sexes between 18 and 60 years. Safety and immunogenicity were assessed during the observation period of 12 months. Immunogenicity was assessed with GP-specific ELISA, IFN-γ ELISA, and plaque pseudoneutralization assay. Vaccinated participants showed marked GP-specific IFN-γ response at day 28 and neutralizing response at day 42 (GMT = 32.6, seroconversion rate 96.3%). GP-specific IgG antibody levels in vaccinated participants peaked at day 42 (GMT = 9345) and persisted for a year after vaccination (GMT = 650). The vaccine showed favorable safety profile and induced robust cell-mediated immune response and strong humoral immune response that lasts at least for a year from the start of vaccination. The study was funded by the Ministry of Health of Russian Federation; GamEvac-Combi ClinicalTrials.gov number, NCT03072030 , Pan African Clinical Trial Registry PACTR201702002053400.

Background. The pandemic of the new coronavirus infection has challenged the medical community for quickly finding and implementing effective methods of treatment. In the absence of a vaccine or specific therapy with proven effectiveness, the usage of convalescent plasma can be the one of perspective methods. An important aspect of this technology is the efficient and safe preparation of convalescent plasma. To date, in the world literature there are practically no publications about donor recruitment and the specifics of the preparation of convalescent plasma. Purpose of the research. Presentation of the experience of organizing a workflow for recruiting donors and stockpiling of convalescent plasma with a high titer of virus-neutralizing antibodies to SARS-CoV-2. Methods. The analysis of the work of the Blood Service of the Moscow Department of Health for stockpiling of COVID-19 convalescent plasma has been executed. In total it has been stockpiled 1240 doses. The normative documentation has been developed by a working group on the basis of the current federal legislation of Russian federation and been approved by the Moscow Department of Health. The titer of neutralizing antibodies (VNA) has been determined as the basic method for assessing the immunological viability of convalescent plasma. The main characteristics of donors, the characteristics of the disease course, the results of preliminary testing for the presence of specific antibodies by ELISA and CLIA methods has been compared with VNA titers in the stockpiled convalescent plasma. Results. Due to a Moscow Health Departments order No. 325 dated 01.04.2020 (a basic local regulatory document) it has been developed a regulation for the stockpiling, examination, storage, safety and transfering of fresh frozen pathogen-reduced plasma of COVID-19 convalescent donors to medical organizations of the Moscow Health Department. For arranging an interaction with donors it has been created a call-center. For effective preliminary selection, it has been formed a donor characteristics list, which has been combined with screening of specific antibodies by ELISA and CLIA methods. Conclusions. Developed a system of recruiting donors and procurement process of convalescent plasma for treatment СOVID-19, which includes the necessary regulations, algorithms for the selection and recruitment of donors, the registry of donors and recipients, algorithms, efficiency and safety of convalescent plasma.