Research Institute of Influenza

Background/Objectives: Influenza B virus infection contributes substantially to annual morbidity and mortality, accounting for 20% to 30% of influenza-associated deaths worldwide. Although vaccination reduces the risk of severe disease, widely used inactivated influenza vaccines are often insufficient to prevent virus transmission. Moreover, influenza B viruses are less susceptible to commonly used antivirals than influenza A viruses. New approaches are therefore required to decrease disease burden and limit virus spread. Neomycin, an aminoglycoside antibiotic, was recently shown to mitigate SARS-CoV-2 transmission in a hamster model. Here, we conducted an exploratory study to assess the effect of neomycin on influenza B virus transmission. Methods: Contact transmission was evaluated using a guinea pig model (n = 4 per group), and aerosol transmission was assessed using a ferret model (n = 6 per group). Animals in the experimental groups received neomycin sulfate (5 mg/guinea pig, 20 mg/ferret) or placebo intranasally, starting one day before exposure to infected animals and continuing for four days thereafter. In the guinea pig study, an additional control group received intranasal interferon alpha. Viral transmission to contact animals was assessed by RT-PCR and virus culture of nasal washes collected over two weeks. Clinical signs and body weight were monitored daily. Results: In the guinea pig model, 75% of contact animals became infected with influenza B virus regardless of treatment. Neither neomycin nor interferon alpha prevented infection, although both delayed the onset of viral shedding in contact animals. In the ferret model, infection occurred in 33% of placebo-treated contact animals, whereas no viral shedding was detected in the neomycin-treated group. Conclusions: Prophylactic intranasal neomycin treatment has the potential to protect exposed individuals from aerosol transmission of influenza B virus during influenza outbreaks.

Palladium(II) cyclometalated complexes combine the properties of aromatic compounds and platinum group metals in terms of the ability to bind DNA and even double-stranded RNA. In this study, the activity of palladium(II) ethylenediamine complexes with Nile red (PdEnNR), coumarine 6 (PdEnC6) and 7,8-benzoquinoline (PdEnBhq) was tested against human cancerous and non-cancerous cells, as well as against mycoplasma pathogens of humans, poultry and plants. It was found that only PdEnC6 transiently reduced A549 cell proliferation after 72h, and cell counts were normalized after 96h, while PdEnNR and PdEnBhq did not demonstrate any significant influence on cancer cells. In relation to non-cancerous FLEH-1097/30 cells, only PdEnBhq had a limited toxic effect. At the same time, PdEnNR showed weak activity against mycoplasmas, but the minimum inhibitory concentrations of PdEnC6 and PdEnBhq against poultry pathogen Mycoplasma gallisepticum and human pathogen Mycoplasma arginini correspond to that of a number of commercial antibacterial drugs. We assume that these complexes or their derivatives can be promising agents for treating mycoplasma-infected cell cultures used in science or biotechnology or perspective drugs for controlling mycoplasma infections.

Rationale.According to the World Health Organization, seasonal influenza causes approximately 3 to 5 million cases of severe illness requiring hospitalization annually, with 290,000 to 650,000 of these cases resulting in death. Recombinant antibodies represent one of the most modern and promising classes of drugs for effective influenza therapy. Objective.To evaluate the properties, specificity, and virus-neutralizing activity of the recombinant antibody FM08, targeting the stem domain of influenza virus hemagglutinin, in the IgA1 and IgG1 formats. Methods.Expression plasmids were constructed using molecular genetic techniques. Experimental samples of FM08 antibody of IgA1 and IgG1 isotypes were produced by transient expression in HEK293 cell culture under serum-free conditions and subsequently purified. Biological activity was assessed comparatively using electrophoretic separation, ELISA, and a microneutralization assay. The study utilized influenza A virus strains of subtypes H1N1pdm, H2N2, H3N2, H5N1, as well as influenza B virus strains (from both genetic lineages). Results.The genetic constructs were shown to enable the accumulation of recombinant FM08 antibodies of IgA1 and IgG1 isotypes in eukaryotic cell cultures. Both FM08 antibody isotypes exhibited nearly identical binding patterns and, starting from a concentration of 16 ng/µl, interacted with influenza A virus strains from both phylogenetic groups, with the exception of the H1N1 1934 strain. The 50% inhibitory concentration (IC₅₀) for binding was 1.49 µg/ml. FM08 antibodies of both IgA1 and IgG1 isotypes neutralized influenza A/California/07/09 (H1N1pdm09) virus with IC₅₀ values of 1–4 µg/ml and influenza A/Cambodia/e0826360/2020 (H3N2) virus with IC₅₀ values of 20 µg/ml. Conclusion.The study of thein vitrobiological activity of the obtained experimental FM08 antibody samples of IgA1 and IgG1 isotypes demonstrated their high potential as an antiviral agent.

The article analyzes the economic and structural transformations in the Russian media industry driven by the implementation of generative artificial intelligence (AI) technologies. The study aims to identify key changes and characterize the new business models emerging from them. The methodology includes case studies of leading market players, content analysis of industry publications, and analysis of expert opinions. It is established that in the current stage (2022–2025), the optimization model of AI use prevails, focusing on cost reduction in production cycles rather than on creating breakthrough products. A key feature of the Russian market is the formation of strong technological ecosystems (Sber, Yandex), which leads to increased market concentration. Simultaneously, the accessibility of AI tools promotes the “democratization” of content production at the grassroots level, creating new market niches. The conclusion is drawn about the dual nature of the transformation: market polarization between large ecosystem players and numerous independent niche producers.

BACKGROUND: The prevalence of recurrent aphthous stomatitis approaches 65% and has been progressively increasing in recent decades. Despite numerous research, the causes of this condition remain poorly understood. In recent years, the focus has been on the relationship between recurrent aphthous stomatitis and various infectious and non-infectious diseases that trigger it. AIM: This study aimed to assess the incidence of recurrent aphthous stomatitis in patients with various oral mucosal diseases, as well as to establish the relationship with various infectious and non-infectious comorbidities. METHODS: A retrospective analysis of medical records of patients admitted to the S.P. Botkin Clinical Infectious Diseases Hospital between January 2022 and December 2023, with the following secondary diagnosis according to the 10th revision of the International Classification of Diseases: K12 Stomatitis and related lesions. Age- and sex-related characteristics of patients, length of hospital stay, and relationship with infectious and non-infectious diseases were analyzed. The proportion of aphthous stomatitis in oral mucosal diseases was assessed. RESULTS: The study included medical records of 334 patients. A higher incidence of recurrent aphthous stomatitis was reported in patients with acute upper respiratory tract infections, acute tonsillitis, and disorders complicated by respiratory failure. CONCLUSION: The findings indicate that infections trigger chronic aphthous stomatitis relapses, confirming the multifactorial nature of the underlying disease.

Self-amplifying RNA (saRNA) is a promising platform for the production of vaccines, anti-tumor therapeutics, and gene therapy solutions. One of the advantages of the saRNA platform is the ability to use small doses of the therapeutic while maintaining prolonged expression of the target protein. However, the presence of auxiliary sequences encoding non-structural alphavirus proteins, which facilitate the replication of saRNA in cells, necessitates a thorough assessment of the biosafety of this platform. In our review, we focus on saRNA functions in the context of its interaction with the innate immune system. Firstly, an analysis is conducted of the side effects of candidate saRNA therapeutics, as observed in preclinical and clinical trials. Then, the mechanisms underlying the function of saRNA products derived from various alphavirus genomes in cell systems are discussed, as well as the reasons for their reactogenicity. The key approaches to optimizing the saRNA platform, which are aimed at reducing the activation of the innate immune response and cytopathic effects, are described. To summarize, this review enables us to systematize our knowledge on the advantages and disadvantages of saRNA, as well as potential approaches to improving this platform in order to develop more effective and safer therapeutics.

Influenza B viruses, divided into B/Victoria and B/Yamagata lineages, have not had B/Yamagata isolates after 2020. A study evaluated immunity to influenza B surface antigens hemagglutinin (HA) and neuraminidase (NA) in 138 patient sera from 2023 and 23 pairs of sera from 2018 to 2019 vaccine recipients. The phylogenetic tree of the influenza B virus, based on HA and NA genes, shows that the Yamagata lineage evolves gradually, while the Victoria lineage exhibits rapid mutations with short branches. In 2023, mean levels of antibodies to HA and NA of B/Yamagata virus were higher than to B/Victoria, despite no cases of B/Yamagata lineage isolation after 2020. The titers of antibodies to NA of B/Yamagata statistically significantly differed among individuals born before and after 1988. Among patients examined in 2018-2019, neuraminidase-inhibiting (NI) antibody titers before vaccination were higher to B/Yamagata than to B/Victoria, and NI antibodies to B/Victoria and B/Yamagata positively correlated with neutralizing antibodies to B/Victoria virus before and after vaccination. Immunity to B/Yamagata virus was stronger in 2023, despite no isolation since 2020, probably due to the presence of cross-reactive antibodies from B/Victoria infections or vaccinations. Antibodies to NA of B/Victoria and B/Yamagata in 2023 correlated significantly in patients born before 1988, potentially supporting the concept of 'antigenic sin' phenomenon for influenza B viruses. The fact that NI antibody titers to B/Victoria and B/Yamagata correlated with neutralizing antibody titers to B/Victoria may suggest broad cross-protection. Studying influenza B virus NA antigenic properties helps understand the evolution and antigenic competition of HA and NA.

To analyze the age-related characteristics of the contribution of influenza viruses, RSV, SARS-CoV-2, other pathogens to the development of severe acute respiratory infections (SARI) in children with an assessment of the disease severity depending on its etiology and epidemic period. SARI monitoring was carried out over six consecutive epidemic seasons, starting from 2018-2019 in 9 infectious hospitals of three cities of Russia with an assessment of the disease severity depending on its etiology. Among all hospitalized children, the proportion of children hospitalized with laboratory-confirmed influenza from 2018 to 2020 ranged from 25.7% to 44.7%, and for RSV infection from 25.7% to 26.8%. However, during the peak of the pandemic, these rates dropped significantly to 0.3% and 1.7%, respectively. In the subsequent three seasons (2021-2024), laboratory-confirmed influenza among hospitalized children was registered in 4.5-20.2% of cases, while RSV infection was identified in 13.4-24.1% of cases, accompanied by a shift in viral subgroups. RSV infections were most severe during the 2022-2023 season, presenting in some cases with hyperthermia, hypoxia, dyspnea, and altered consciousness. Among hospitalized children, the proportion with COVID-19 was relatively low in 2020-2021 (0.8-2.4%) but increased significantly to 10.6%-13.6% following the emergence of the Omicron variant in 2022, before decreasing again in subsequent years. The main genetic lineages of SARS-CoV-2 circulating in the Russian Federation are presented. Influenza and RSV viruses were predominant among viral pathogens identified in hospitalized children aged ≤ 2 years. COVID-19 cases among children were relatively rare and generally less severe compared to RSV and rhinovirus infections.

BACKGROUND: The delivery of nucleic acids to mesenchymal stem cells, which are used as model objects in in vitro experiments or as therapeutic agents in regenerative medicine and oncology, is an actively developing area of research. Existing non-viral delivery systems either have low effectiveness or highly toxic to mesenchymal stem cells. Therefore, the development of new carriers has become an urgent priority. AIM: To demonstrate the feasibility of delivering model messenger RNA and small interfering RNA to rat heart mesenchymal stem cells (MSCs) in vitro using original cationic liposomes 2X3-DOPE (1:3 molar ratio) and to evaluate the influence of exosomes incorporated into hybrid nanoparticles with 2X3-DOPE on the efficiency of RNA delivery. METHODS: Exosomes were isolated using a standard ultracentrifugation technique followed by characterization of the obtained vesicles through Western blotting, transmission electron microscopy, atomic force microscopy, and hydrodynamic diameter measurement using dynamic light scattering. Small interfering RNA was chemically synthesized; whereas messenger RNA was obtained by in vitro transcription. Complexes of liposomes or hybrid nanoparticles with RNA were prepared by mixing; the properties of the resulting particles were assessed using dynamic light scattering and atomic force microscopy. To evaluate the efficiency of RNA delivery to rat heart mesenchymal stem cells derived from both healthy and ischemic myocardium, we used fluorescence microscopy, laser scanning confocal microscopy, and flow cytometry. RESULTS: Complexes of cationic liposomes 2X3-DOPE (1:3 molar ratio) with messenger RNA and 2X3-DOPE modified with DSPE-PEG2000 (0.62 mol%) complexed with small interfering RNA were successfully prepared and characterized. It was demonstrated that 2X3-DOPE is ineffective for messenger RNA delivery to rat cardiac mesenchymal stem cells; whereas hybrid nanoparticles incorporating exosomes based on these liposomes exhibited up to 40% transfection efficiency. In addition, 2X3-DOPE modified with DSPE-PEG2000 (0.62 mol%) was effective for small interfering RNA delivery to rat cardiac mesenchymal stem cells, achieving up to 90% transfection efficiency; whereas the use of hybrid nanoparticles based on this formulation resulted in 100% transfected cells with more than a twofold increase in small interfering RNA in the cells as indicated by the average fluorescence intensity. CONCLUSION: Cationic liposomes 2X3-DOPE (1:3 molar ratio) modified with DSPE-PEG2000 (0.62 mol%) are promising vehicles for small interfering RNA delivery to mesenchymal stem cells, both independently and in combination with exosomes. Exosomes integrated in hybrid nanoparticles based on 2X3-DOPE improve the transfection efficiency of both messenger RNA and small interfering RNA in rat cardiac mesenchymal stem cells in vitro.

Cases of new COVID-19 infection, which manifested in 2019 and caused a global socioeconomic crisis, still continue to be registered worldwide. The high mutational activity of SARS-CoV-2 leads to the emergence of new antigenic variants of the virus, which significantly reduces the effectiveness of COVID-19 vaccines, as well as the sensitivity of diagnostic test systems based on variable viral antigens. These problems may be solved by focusing on highly conserved coronavirus antigens, for example nucleocapsid (N) protein, which is actively expressed by coronavirus-infected cells and serves as a target for the production of virus-specific antibodies and T cell responses. It is known that anti-N antibodies are non-neutralizing, but their protective potential and functional activity are not sufficiently studied. Here, the protective effect of anti-N antibodies was studied in Syrian hamsters passively immunized with polyclonal sera raised to N(B.1) recombinant protein. The animals were infected with 105 or 104 TCID50 of SARS-CoV-2 (B.1, Wuhan or BA.2.86.1.1.18, Omicron) 6 h after serum passive transfer, and protection was assessed by weight loss, clinical manifestation of disease, viral titers in the respiratory tract, as well as by the histopathological evaluation of lung tissues. The functional activity of anti-N(B.1) antibodies was evaluated by complement-dependent cytotoxicity (CDC) and antibody-dependent cytotoxicity (ADCC) assays. The protection of anti-N antibodies was evident only against a lower dose of SARS-CoV-2 (B.1) challenge, whereas almost no protection was revealed against BA.2.86.1.1.18 variant. Anti-N(B.1) monoclonal antibodies were able to stimulate both CDC and ADCC. Thus, anti-N(B.1) antibodies possess protective activity against homologous challenge infection, which is possibly mediated by innate Fc-mediated immune reactions. These data may be informative for the development of N-based broadly protective COVID-19 vaccines.