Objective was to investigate the SARS-CoV-2 collective immunity status of the population of Belarus within the context of the COVID-19 pandemic. Materials and methods. The work was carried out according to the methodology for assessing SARS-CoV-2 population immunity, developed by Rospotrebnadzor Russia and the Ministry of Health of Belarus with the participation of the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The Bioethics Committee of Belarus and the local ethics committee of the St. Petersburg Pasteur Institute approved the study. Selection of participants was carried out using a questionnaire method and online technology (internet, cloud server). Volunteers were randomized into seven age groups (years of age): 1–17; 18–29; 30–39; 40–49; 50–59; 60–69; and 70+. Regional randomization ensured proportional representation of volunteers from each region, and no more than 30 people were included from one enterprise. In accordance with manufacturer instructions, blood plasma samples were analyzed for: IgG antibodies (Abs) to the SARS-CoV-2 nucleocapsid (Nc) using a quantitative ELISA test system; and IgG Abs to the receptor binding domain (RBD) of the SARS-CoV-2 S (spike) surface glycoprotein using a qualitative ELISA test system. Statistical processing was carried out using Excel 2010 and other software. Statistical differences were designated as significant when p 0.05, unless otherwise indicated. Results. The level of seroprevalence, in terms of Abs to Nc among the Belarusian population, was 38.4% (95% CI 37.6–45.4). The highest Ab levels were found among individuals in older age groups (50-70+ years old). The lowest were found in children 1–17 years old and in young people 18–39 years old The distribution of seroprevalence across Belarusian regions was relatively homogeneous, with the exception of the Minsk Region, where a statistically significant decrease in the indicator was noted. In terms of profession, the largest share of seropositive individuals was found among transportation workers; the smallest was found in business. The moderate COVID-19 incidence has not led to a dramatic increase in the number of contacts. The base reproduction number (R0) was 1.3. In the Republic of Belarus, there was a moderate level of asymptomatic COVID-19 among seropositive individuals (45.3% [95% CI 44.0–46.7]). This form of infection was observed most often among children aged 1–17 years old (65.0% [95% CI 61.3–68.6]). In parallel with seroprevalence assessment, SARS-CoV-2 vaccination was carried out. We used two vaccines: Gam-COVID-Vac (also known as Sputnik V, developed by Gamaleya National Center for Epidemiology and Microbiology, Russia); and BBIBP-CorV (Sinopharm, PRC). Vaccination against SARS-CoV-2 was accompanied by an increase in the level of anti-RBD Abs (95% [95% CI 94.7–96.7]). Taking into account the vaccination of a subset of the population with BBIBP-CorV, the overall herd immunity, inferred from the analyzed indicators (presence of anti-Nc or anti-RBD Abs), was 47.1% (95% CI 46.3–48.0). Conclusion. COVID-19 in Belarus was characterized by a moderately pronounced course of the epidemic process. The threshold level of herd immunity to SARS-CoV-2 has not yet been reached, as a result of which the conditions for progression of the epidemic remain.

Myeloid-derived suppressor cells (MDSCs) are an immunosuppressive population involved in pathological processes associated with chronic inflammation. In recent years, the role of these cells in the regulation of a number of non-pathological processes, in particular, in the development of vaccine-induced immune response, has been actively discussed. This work was aimed at investigating the role of MDSC in the development of an immune response in old mice immunized with an inactivated whole virion SARS-CoV-2. Immunization of old animals induced an increase in the relative content of B cells and the production of specific antibodies to S1 and N proteins of SARS-CoV-2 in titers comparable to those of young animals. At the same time, elevated MDSC levels in aged animals negatively correlated with the level of CD8+ T cells. Splenic MDSCs in old animals were characterized by increased production of reactive oxygen species compared to young animals. In vitro experiments showed that MDSC depletion increased antigen-specific production of IFNγ by CD4+ T cells. The data obtained suggest a negative role for MDSC in regulating the T-cell vaccine-induced response to inactivated SARS-CoV-2 and encourage further studies in this direction, which may be a key to developing approaches to increase the efficacy of vaccines against SARS-CoV-2 in at-risk groups.

Comparison of taxonomic and functional structures of macrobenthic communities in the eelgrass meadows of Zostera marina L. was conducted for the White Sea and Azov Sea regions. In the meadows, Z. marina in both regions formed almost monospecific beds interspersed in the White Sea with single specimens of other macrophytes. In each region, two groups of macrozoobenthos communities were identified: with the dominance of Mytilus spp. (Mytilus galloprovincialis in the Sea of Azov and Mytilus edulis in the White Sea) and with the dominance of other species. However, the role of Mytilus spp. was not key in eelgrass meadows: the variation in the macrozoobenthic species abundance did not depend on mussels' quantitative characteristics. No common macrofaunal species were found for the two regions; however the functional structure of macrozoobenthos across these two contrasting latitude zones showed similarities. Filter feeders and detritivores with similar life strategies dominated both regions (maximal body size ranged from 1 to 3 cm, epifaunal lifestyle, and high fecundity). Such functional convergence within the communities exceeded latitudinal differences between faunas, supporting the hypothesis that similar ecological mechanisms underlie the formation of macrozoobenthic communities in seagrass meadows even when fauna originates differently. In both areas, key community structure drivers included grain size composition of bottom sediments as well as abundance of Z. marina.

Целью исследования явилось изучение влияния гемопоэтических стволовых клеток (ГСК) костного мозга в условиях культивирования ex vivo с цитокинами на их индукционно-регенеративную способность при экспериментальном инфаркте миокарда. Опыты проводили на беспородных белых крысах обоего пола. Модель мелкоочагового инфаркта миокарда создавали путем внутрибрюшинного введения адреномиметика изопротеренола. CD 117+ ГСК выделяли из фракции костного мозга с плавучей плотностью 1,09 г/мл с помощью иммуномагнитной сепарации и культивировали 48 ч в присутствии IL-3, после чего исследовали экспрессию рецептора CXCR4 и продукцию TGF с помощью иммуноферментного анализа. Стимулированные IL-3 ГСК метили флуоресцентной меткой (CFSE) и вводили внутривенно животным с мелкоочаговым инфарктом миокарда. Оценивали продукцию фактора хоуминга SDF-1 в сердечной мышце после инфаркта, миграцию меченых ГСК в сердечную ткань и гистоморфологические изменения регенеративного характера. Установлено, что IL-3 достоверно усиливал экспрессию CXCR4 и секрецию TGF при трехсуточном культиивровании. На 7-е сут. после введения изопротеренола наблюдалась тенденция к усилению продукции фактора хоуминга SDF-1 в сердечной мышце, которая затем исчезала по мере развития инфаркта миокарда. Локализация и характер изменений, происходящих в миокарде крыс, индуцированных изопротеренолом морфологически соответствовал мелкоочаговому инфаркту миокарда. Гистоморфологический анализ показал, что в случае введения стимулированных ГСК процессы репаративного моделирования миокарда и неоангиогенез усиливались. Проведенные эксперименты показывают перспективность использования новых подходов к усилению потенциальных регенеративных свойств ГСК костного мозга для печения острого инфаркта миокарда.