The SARS-CoV-2 virus caused the COVID-19 pandemic is related to the SARS-CoV-1 and MERS coronaviruses, which were resulted in 2003 and 2012 epidemics. Antibodies in patients with COVID-19 emerge 714 days after the onset of symptoms and gradually increase. Because the COVID-19 pandemic is still in progress, it is hard to say how long the immunological memory to the SARS-CoV-2 virus may be retained. The aim of this study was to study a ratio between humoral and cellular immunity against the SARS-CoV-2 S protein in COVID-19 convalescents. There were enrolled 60 adults with mild to moderate COVID-19 2 to 12 months prior to the examination. The control group consisted of 15 adults without COVID-19 or unvaccinated. Specific antibodies to the SARS-CoV-2 virus were determined by ELISA with the SARS-CoV-2-IgG-ELISA-BEST kit. To determine the specific IgG and IgA subclasses, the anti-IgG conjugate from the kit was replaced with a conjugate against the IgG subclasses and IgA. Additional incubation with or without denaturing urea solution was used to determine the avidity of antibodies. Peripheral blood mononuclear cells were isolated by gradient centrifugation, incubated with or without coronavirus S antigen for 20 hours, stained by fluorescently labeled antibodies, and the percentage of CD8highCD107a cells was assessed on flow cytometer BD FACSCanto II. In the control group, neither humoral nor cellular immunity against the SARS-CoV-2 S protein was found. In the group of convalescents, the level of IgG antibodies against the SARS-CoV-2 S protein varies greatly not being strictly associated with the disease duration, with 57% and 43% of COVID-19 patients having high vs. low level of humoral response, respectively. A correlation between level of specific IgG and IgA was r = 0.43. The avidity of antibodies increased over time in convalescents comprising 49.9% at 612 months afterwards. No virus-specific IgG2 and IgG4 subclasses were detected, and the percentage of IgG1 increased over time comprising 100% 612 months after recovery. 50% of the subjects examined had high cellular immunity, no correlations with the level of humoral immunity were found. We identified 4 combinations of humoral and cellular immunity against the SARS-CoV-2 S protein: high humoral and cellular, low humoral and cellular, high humoral and low cellular, and vice versa, low humoral and high cellular immunity.

The question on the duration and effectiveness of post-infection vs post-vaccination SARS-CoV-2 immunity remains in the focus of numerous studies. The aim of the work was to examine the duration of maintained post-infection and post-vaccination SARS-CoV-2 immunity as well as formation of hybrid (vaccination after infection) and breakthrough (repeated disease or disease after vaccination) immunity in the context of an ongoing COVID-19 pandemic. 107 adults with mild or moderate COVID-19 318 months after the disease and 30 subjects vaccinated twice with the Sputnik V vaccine were examined 16 times. Antibodies against SARS-CoV-2 virus were determined by ELISA on the SARS-CoV-2-IgG quantitative-ELISA-BEST test systems. The antibody avidity was measured by additional incubation with and without denaturing solution. Mononuclear cells were isolated from blood by gradient centrifugation, incubated with and without coronavirus S-protein for 20 hours, stained with fluorescently labeled antibodies, and the percentage of CD8highCD107a+ was counted using FACSCanto II cytometer. It was shown that in the group of convalescent and vaccinated subjects, the level of virus-specific antibodies decreased more deeply in individuals with initially high humoral response, but 9 months later the decrease slowed down and reached a plateau. The antibody avidity rose up to 50% and persisted for 18 months. Cellular immunity in recovered patients did not change for 1.5 years, while in vaccinated patients it gradually decreased 6 months later, but remained at detectable level. After revaccination, a significant increase in the level of antibodies, avidity up to 67.6% and cellular immunity returned to the initial level were noted. Hybrid immunity turned out to be significantly higher than post-infection and post-vaccination immunity. The level of antibodies increased to 1218.2 BAU/ml, avidity to 69.85%, and cellular immunity to 9.94%. Breakthrough immunity was significantly higher than that after the first disease. The level of antibodies rose to 1601 BAU/ml, avidity up to 81.6%, cellular immunity up to 13.71%. Using dynamic observation of four COVID-19 convalescents, it has been shown that in the context of the ongoing pandemic and active coronavirus mutation, natural boosting occurs both asymptomatically and as a result of a mild re-infection, which prevents disappearance of SARS-CoV-2 humoral and cellular immunity.

Обоснование. Известна важная роль митохондрий в механизмах повреждения и гибели клеток мозга при черепно-мозговой травме (ЧМТ). Однако вопросы взаимоотношений между тяжестью повреждения мозга при ЧМТ и митохондриальной дисфункцией окончательно не решены. Цель исследования: определить активность NADH- и сукцинатдегидрогеназ —ключевых ферментов окислительного фосфорилирования митохондрий; содержание аденозинтрифосфата в лимфоцитах при ЧМТ; уровень NOx и 3-нитротирозина в периферической крови у детей, перенесших травмы различной степени тяжести и имеющих разные исходы ЧМТ. Материалы и методы: определение указанных показателей проводилось в динамике до одного месяца, а в отдельных случаях — вплоть до гибели больных. Тяжесть ЧМТ оценивали в баллах по шкале комы Глазго, исход ЧМТ — по шкале исходов Глазго. Детей с ЧМТ на основании клинической оценки разделили на 3 группы — с легкой, тяжелой и с тяжелой ЧМТ и летальным исходом. Результаты: исследования показали, что активность дегидрогеназ достоверно снижалась только у больных с тяжелой ЧМТ и неблагоприятным исходом. Наибольшее снижение этих показателей выявлено у больных с летальным исходом. Обнаружена прямая корреляционная зависимость между показателями активности дегидрогеназ и содержанием аденозинтрифосфата в лимфоцитах (r =0,97, p =0,005). Содержание метаболитов NOx у детей с тяжелой ЧМТ на порядок превышало их уровень у здоровых детей и больных с легкой ЧМТ. Уровень 3-нитротирозина в плазме крови был тем выше, чем тяжелее была ЧМТ. Заключение. Обнаруженные при ЧМТ у детей митохондриальная дисфункция, нарушение мозгового энергетического обмена и окислительный стресс могут приводить к повреждению и гибели клеток мозга, а также быть мишенями для адекватной терапии ЧМТ.

The development of multiple organ failure and septic complications increases the cumulative risk of mortality in children with severe injury. Clinically available biochemical markers have shown promise in assessing the severity and predicting the development of complications and outcomes in such cases. This study aimed to determine informative criteria for assessing the severity and outcome prediction of severe injury in children based on levels of mid-regional proadrenomedullin (MR-proADM) procalcitonin (PCT), neuron-specific enolase (NSE), and protein S100. Biomarker levels were measured in 52 children with severe injury (ISS ≥ 16) on the 1st, 3rd, 7th, and 14th days after admission to the ICU. The children were divided into groups based on their favorable (n = 44) or unfavorable (n = 8) outcomes according to the Severe Injury Outcome Scale, as well as their favorable (n = 35) or unfavorable (n = 15) outcomes according to the Glasgow Coma Outcome Scale (GOS). The study also evaluated the significance of biomarker levels in predicting septic complications (with SC (n = 16) and without SC (n = 36)) and diagnosing and stratifying multiple organ failure (with MOF (n = 8) and without MOF (n = 44)). A comprehensive assessment of MR-proADM and PCT provided the highest diagnostic and prognostic efficacy for early diagnosis, risk stratification of multiple organ failure, and outcome prediction in severe injury cases involving children. Additionally, the inclusion of the S100 protein in the study allowed for further assessment of brain damage in cases of traumatic brain injury (TBI), contributing to the overall prognostic model.

Introduction. Currently, there is an increase in the incidence and an increase in the severity of the course of COVID-19 in children. The tropism of the SARS-CoV-2 virus to the cardiovascular system has been established, while post-COVID syndrome with various manifestations is recorded in 25% of recovered adolescents. The purpose of the work was to identify the features of the electrocardiogram (ECG) pattern in children hospitalized with a diagnosis of COVID-19. Results. Significant changes in the conductivity and activity of the left heart myocardium were found in COVID-19 patients with pneumonia and respiratory failure. Pronounced changes in ECG indices were found in children of senior school age who were admitted for treatment 2.4 times more often than other children. Proarrhythmogenic ECG indices in children were detected in severe COVID-19 - with community-acquired pneumonia (ΔQTc, QTcmin) and respiratory failure (TpTe/QTmax). These ECG changes, combined with the trend in inflammation markers (an increase in the C-reactive protein level and a decrease in the number of lymphocytes) in children with a moderate course of COVID-19 may be a sign of the involvement of the myocardium in an infectious inflammatory process. This suggests that the effect on the myocardium is exerted by systemic inflammation and not by the hemodynamic overload of the right heart, which is expected in pulmonary pathology. Conclusion. The obtained data indicate the need for dynamic ECG monitoring during the acute stage of the disease and rehabilitation of children who suffered from COVID-19.