An ELISA Platform for the Quantitative Analysis of SARS-CoV-2 RBD-neutralizing Antibodies As an Alternative to Monitoring of the Virus-Neutralizing Activity.

Monitoring of the level of the virus-neutralizing activity of serum immunoglobulins ensures that one can reliably assess the effectiveness of any protection against the SARS-CoV-2 infection. For SARS-CoV-2, the RBD-ACE2 neutralizing activity of sera is almost equivalent to the virus-neutralizing activity of their antibodies and can be used to assess the level of SARS-CoV-2 neutralizing antibodies. We are proposing an ELISA platform for performing a quantitative analysis of SARS-CoV-2 RBD-neutralizing antibodies, as an alternative to the monitoring of the virus-neutralizing activity using pseudovirus or "live" virus assays. The advantage of the developed platform is that it can be adapted to newly emerging virus variants in a very short time (1-2 weeks) and, thereby, provide quantitative data on the activity of SARS-CoV-2 RBD-neutralizing antibodies. The developed platform can be used to (1) study herd immunity to SARS-CoV-2, (2) monitor the effectiveness of the vaccination drive (revaccination) in a population, and (3) select potential donors of immune plasma. The protective properties of the humoral immune response in hospitalized patients and outpatients, as well as after prophylaxis with the two most popular SARS-CoV-2 vaccines in Russia, were studied in detail using this platform. The highest RBD-neutralizing activity was observed in the group of hospitalized patients. The protective effect in the group of individuals vaccinated with Gam-COVID-Vac vaccine was 25% higher than that in outpatients and almost four times higher than that in individuals vaccinated with the CoviVac vaccine.

The value of indicators characterizing the state of the cardiovascular system in assessing the hospital prognosis of COVID-19 patients.

Background     Heart damage is one of complications of the novel coronavirus infection. Searching for available predictors for in-hospital death and survival that determine the tactic of managing patients with COVID-19, is a challenge of the present time.Aim      To determine the role echocardiographic (EchoCG) parameters in evaluation of the in-hospital prognosis for patients with the novel coronavirus infection, COVID-19.Material and methods  The study included 158 patients admitted for COVID-19. EchoCG was performed for all patients. The role of left ventricular (LV) ejection fraction (EF) was analyzed in various age groups. EchoCG data were compared with the clinical picture, including the severity of respiratory failure (RF), blood oxygen saturation (SрО2), data of computed tomography (CT) of the lungs, and blood concentration of troponin. Comorbidity was analyzed, and the highest significance of individual pathologies was determined.Results LV EF ≤40 % determined the worst prognosis of patients with COVID-19 (p<0.0001), including the age group older than 70 years (р=0.013). LV EF did not correlate with the degree of lung tissue damage determined by CT upon admission (р=0.54) and over time (р=0.23). The indexes that determined an adverse in-hospital prognosis to a considerable degree were pericardial effusion (p<0.0001) and pulmonary hypertension (p<0.0001). RV end-diastolic dimension and LV end-diastolic volume did not determine the in-hospital mortality and survival. Blood serum concentration of troponin I higher than 165.13 µg/l was an important predictor for in-hospital death with a high degree of significance (р<0.0001). Th degree of RF considerably influenced the in-hospital mortality (р<0.0001). RF severity was associated with LV EF (р=0.024). The SpO2 value determined an adverse immediate prognosis with a high degree of significance (р=0.0009). This parameter weakly correlated with LV EF (r=0.26; p=0.0009). Patients who required artificial ventilation (AV) constituted a group with the worst survival rate (р<0.0001). LV EF was associated with a need for AV with a high degree of significance (р=0.0006). Comorbidities, such as chronic kidney disease, postinfarction cardiosclerosis and oncologic diseases, to the greatest extent determined the risk of fatal outcome.Conclusion      EchoCG can be recommended for patients with COVID-19 at the hospital stage to determine the tactics of management and for the in-hospital prognosis.

Prospects for using radionuclide research methods for diagnosing and evaluating effectiveness of treating consequences of coronavirus diseasr (covid-19)

Purpose: To determine the role of nuclear medicine methods in the diagnosis and quality control of treatment and rehabilitation of patients with complications after coronavirus diseasr (COVID-19) The article provides a brief analysis of the incidence of COVID-19 and highlights the role of diagnosis, treatment and rehabilitation of patients suffering from the consequences of coronavirus diseasr after the end of the pandemic. The most common clinical manifestation of coronavirus diseasr is bilateral interstitial pneumonia, one of the complications of which is the development of acute respiratory distress syndrome, its pathogenesis is highlighted. It is also noted that the leading link in the development of the disease is a systemic lesion of the endothelial vascular wall, which is the cause of thrombosis and its complications, primarily pulmonary embolism, ischemic brain infarctions and cardiovascular catastrophes. Specific methods of radionuclide diagnostics are described for individual organs and systems: Respiratory, cardiovascular, brain, and others. The need to diagnose and control the quality of treatment and rehabilitation of patients with post-inflammatory changes in the parenchyma of internal organs and a decrease in their functional ability due to sclerotic changes, patients with changes in the state due to the transition of inflammation to the chronic stage, as well as with an overactive immune response to inflammatory changes. Conclusion: At the stage of diagnosis and treatment of the consequences of a previous coronavirus diseasr and subsequent rehabilitation, molecular imaging methods are essential in a complex of studies. © 2021 State Research Center, Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency. All rights reserved.

COVID-19 in Russia: Clinical and Immunological Features of the First-Wave Patients.

The coronavirus disease outbreak in 2019 (COVID-19) has now achieved the level of a global pandemic and affected more than 100 million people on all five continents and caused over 2 million deaths. Russia is, needless to say, among the countries affected by SARS-CoV-2, and its health authorities have mobilized significant efforts and resources to fight the disease. The paper presents the result of a functional analysis of 155 patients in the Moscow Region who were examined at the Central Clinical Hospital of the Russian Academy of Sciences during the first wave of the pandemic (February-July, 2020). The inclusion criteria were a positive PCR test and typical, computed tomographic findings of viral pneumonia in the form of ground-glass opacities. A clinical correlation analysis was performed in four groups of patients: (1) those who were not on mechanical ventilation, (2) those who were on mechanical ventilation, and (3) those who subsequently recovered or (4) died. The correlation analysis also considered confounding comorbidities (diabetes, metabolic syndrome, hypertension, etc.). The immunological status of the patients was examined (levels of immunoglobulins of the M, A, G classes and their subclasses, as well as the total immunoglobulin level) using an original SARS-CoV-2 antibody ELISA kit. The ELISA kit was developed using linear S-protein RBD-SD1 and NTD fragments, as well as the N-protein, as antigens. These antigens were produced in the prokaryotic E. coli system. Recombinant RBD produced in the eukaryotic CHO system (RBD CHO) was used as an antigen representing conformational RBD epitopes. The immunoglobulin A level was found to be the earliest serological criterion for the development of a SARS-CoV-2 infection and it yielded the best sensitivity and diagnostic significance of ELISA compared to that of class M immunoglobulin. We demonstrated that the seroconversion rate of "early" N-protein-specific IgM and IgA antibodies is comparable to that of antibodies specific to RBD conformational epitopes. At the same time, seroconversion of SARS-CoV-2 N-protein-specific class G immunoglobulins was significantly faster compared to that of other specific antibodies. Our findings suggest that the strong immunogenicity of the RBD fragment is for the most part associated with its conformational epitopes, while the linear RBD and NTD epitopes have the least immunogenicity. An analysis of the occurrence rate of SARS-CoV-2-specific immunoglobulins of different classes revealed that RBD- and N-specific antibodies should be evaluated in parallel to improve the sensitivity of ELISA. An analysis of the immunoglobulin subclass distribution in sera of seropositive patients revealed uniform induction of N-protein-specific IgG subclasses G1-G4 and IgA subclasses A1-A2 in groups of patients with varying severity of COVID-19. In the case of the S-protein, G1, G3, and A1 were the main subclasses of antibodies involved in the immune response.