Introduction. The surveillance of influenza viruses in ARVI structure and study of their properties in epidemic season 2019–2020 in Russian Federation are actual for investigations due to tasks of Global Influenza Strategy initiated by WHO in 2019.Material and methods. The data of epidemiological surveillance on influenza- and ARVI-associated morbidity and hospitalization in different age groups of population were analyzed; virological, genetic and statistical methods were used.Results. Preschool children were involved in epidemic the most. Meanwhile, the highest rate of hospitalization was observed in patients of 18–40 years old. Influenza A(H1N1)pdm09 virus dominated in etiology of ARVI in hospitalized patients and pneumonia. The role of respiratory viruses in severe cases of pneumonia and bronchoalveolar syndrome in children was shown. The differences in spectrum of circulating viruses caused ARVI in different regions of Russia were found. Influenza A(H1N1)pdm09 and B/Victoria-like viruses were the main etiological agents that caused of epidemic; its activity among all ARVI was 7.3 and 8.0%, respectively. The differences in antigenic properties of influenza A(H3N2) and B epidemic strains compared to vaccine viruses were found. The populations of epidemic strains were presented by following dominant genetic groups: 6B1.A5/183P for A(H1N1)pdm09, 3С.2а1b+137F for A(H3N2) and V1A.3 line B/Victoria-like for B viruses. The good profile of epidemic strains susceptibility to anti-neuraminidase inhibitors has been saved. The most of the studied influenza strains had the receptor specificity characteristic of human influenza viruses.Conclusions. Obtained results identified the peculiarities of viruses caused the influenza and ARVI in epidemic season 2019–2020 in different regions of Russia. These results suggested the important role of influenza A(H1N1) pdm09 in severe cases and pneumonia in adults 18–40 years old. The continuing drift in influenza viruses was found, which, apparently, could not but affect the efficacy of vaccine prophylaxis and was also considered in the recommendations of WHO experts on the composition of influenza vaccines for the countries of the Northern Hemisphere in the 2020–2021 season.

Relevance. The long-term leadership of ARVI pathogens determines their significance in the damage caused to both health and the economy of the country. Aim. To identify the features of the structure of ARVI during the emergence and widespread spread of SARS-CoV-2. Materials and methods. The article uses methods used in epidemiological surveillance of acute respiratory viral infections. Results and discussion. The results of the diagnostic available ARVI pathogens monitoring during epidemic seasons 2018-2021 are presented. The tendency of greater engagement of aged group 15 y.o. and older in epidemic process by morbidity and hospitalization due to SARI was shown. 49 818 nasal swabs from patients with influenza infection, 36 044 – with ARVI and 59 062 – with SARS-CoV-2 were tested. The top three in the structure of ARVI were INF, HEV-D and HRSV (in the 2018–2019 season); INF, SARS-CoV-2 and HEV-D (2019–2020); SARS-CoV-2, HEV-D and HPIV/HCoV (2020–2021). The activity of viral pathogens also differed: for HPIV, HAdV, HEV-D, HMPV, a decrease in activity was noted during the appearance of SARS-CoV-2 (2019–2020) and some of its growth in the following season; in relation to HRSV and INF - a decrease in activity during the last two seasons, and for INF – extremely low activity in the 2020-2021 season; the activity of seasonal HCoV even increased slightly. The data of genetic analyses of SARS-CoV-2 positive samples showed the heterogeneity of its population with a representative of variants (Alfa, Delta) as well as endemic for Russia and Moscow variants only. The recommended composition of influenza virus vaccines for use in the 2021–2022 northern hemisphere influenza season and in the 2022 southern hemisphere influenza season are presented due to their drift changeability. Conclusions. SARS-CoV-2 was influenced by the activity of ARVI pathogens with the almost complete displacement of influenza viruses from the circulation in the period 2020–2021.

New derivatives of the closo-decaborate anion [B₁₀H₉–O(CH₂)₂O(CH₂)₃C(O)–L–OCH₃]²⁻ (An) (1: L = Trp; 2: L = His; 3: L = Met; 4: L = Ala(2-oxopyrrolidin-3-yl) (Pld) were synthesized and isolated as tetraphenylphosphonium salts (Ph₄P)₂An. Anions 1²⁻; 2²⁻; 3²⁻, and 4²⁻ contain a pendant functional group from the L-tryptophan methyl ester, L-histidine methyl ester, L-methionine methyl ester, or methyl 2-amino-3-(2-oxopyrrolidin-3-yl)propanoate (-Trp–OCH₃, -His–OCH₃, -Met–OCH₃, or -Pld–OCH₃) residue, respectively, bonded with the boron cluster anion through the oxybis[(ethane-2,1-diyl)oxy] spacer. This pacer is formed as a result of the nucleophilic opening of the attached dioxane molecule in the [B₁₀H₉O(CH₂)₄O]⁻ starting derivative. Sodium salts of the target compounds were isolated and used in biological experiments. It was established that among compounds Na₂An (An = 1–4), not all are capable of inhibiting the cytopathic effect of the virus in vitro. Sodium salts Na₂An have a low toxic effect on a monolayer of continuous canine embryonic kidney (MDCK) cell line. Compounds Na₂1 and Na₂2 had IC₅₀ of 5.0 and 20.0 μg/mL, respectively, while for compounds Na₂3 and Na₂4, IC₅₀ values could not be achieved at the concentrations studied. The studies performed for molecular docking of the anionic part of 1²⁻ and 2²⁻ with the transmembrane domain of viroporin M2 show some differences in the location of these two ligands inside the M2 canal pore.

The purpose of this work was to determine the characteristics of the circulation of various viral respiratory pathogens during the epidemic season 2022–2023 against the background of the ongoing evolutionary variability of SARS-CoV-2. Materials and methods. The article uses methods used in «traditional» and «hospital» epidemiological surveillance of acute respiratory viral infections. Results and discussion. The period from October 2022 to September 2023 was characterized by early and high activity of influenza A(H1N1)pdm09 virus, which was replaced by influenza B virus. The antigenic and genetic properties of strains were closely related to influenza vaccines viruses recommended by WHO experts for the current season. The effectiveness of influenza vaccines was confirmed (75.0%). All of the studied influenza A(H1N1)pdm09, A(H3N2) and B epidemic strais retained sensitivity to drugs with antineuraminidase activity. The structure and share of other ARVI pathogens have changed somewhat compared to the previous season: There was a tendency to increase the activity of HAdV and HMPV; almost equivalent activity of HRsV, HRV, HCoV and HBoV; and a decrease in HPIV activity. At the same time, the frequency of other ARVI pathogens did not reach the indicators of the pre-pandemic COVID-19 period. The rationale for updating the composition of influenza vaccines for the countries of the Northern Hemisphere in the 2023–2024 season is given.

The emergence of drug-resistant influenza virus strains necessitates the development of novel antiviral agents with unique mechanisms of action. This study presents the synthesis and in vitro evaluation of a new class of antiviral compounds: sodium salts of amino acid ester conjugates based on the closo-dodecaborate anion [B₁₂H₁₂]²⁻, linked via a tetrahydropyran-derived spacer (Na₂[B₁₂H₁₁O(CH₂)₆C(O)X], where X = L-Trp-OMe (Na₂2); L-His-OMe (Na₂3); L-Met-OMe (Na₂4); Pld-OMe (Na₂5)). The antiviral activity was assessed against contemporary, multidrug-resistant influenza A virus strains, including A/Cheboksary/125/2020 (H1N1)pdm09 and A/IIV-Orenburg/83/2012 (H1N1)pdm09. Cross-platform comparison revealed that the dodecaborate-tryptophan conjugate Na₂2 exhibited comparable efficacy to its lead decaborate analog against the Orenburg strain while demonstrating potent activity (IC₅₀ = 5.0 µg/mL) against the Cheboksary strain with reduced susceptibility to neuraminidase inhibitors (oseltamivir; zanamivir) and complete resistance to M2 channel blockers. The histidine-based conjugate Na₂3 also showed significant efficacy against the Cheboksary strain, while methionine and lactam derivatives (Na₂4; Na₂5) remained inactive. This work confirms boron clusters as versatile platforms for antiviral development and establishes structure–activity relationships crucial for optimizing both B₁₀ and B₁₂-based therapeutics against resistant influenza strains.

Активность вирусов гриппа в сезон 2017-2018 гг. в России и странах Северного полушария: конфликт по В-вирусному компоненту вакцин