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SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2), also known as 2019-nCoV (2019-Novel Coronavirus) is a strain of coronavirus from the genus Betacoronavirus, discovered in China at the end of 2019 in patients with pneumonia. Coronavirus infection COVID-19 (COrona VIrus Disease 2019) caused by coronavirus 2019 (COVID-19) has spread around the world at a very fast pace, with death toll exceeding more than 5.2 million people worldwide. Limited success in developing new drugs as well as use of existing drugs for the treatment of COVID-19 resulted in situation when the main prevention measures for a long time were based on testing and isolation of sick subjects, which started to reverse due to vaccination. Monitoring the formation of humoral and T-cell population immunity against the SARS-CoV-2 virus during the COVID-19 pandemic is a necessary element for epidemiological surveillance. ELISA-based methods are widely used to assess humoral immunity, and various test systems including ELISPOT (Enzyme-Linked ImmunoSpot) are used to analyze cellular immunity. The ELISPOT assay is a highly sensitive and specific method for quantifying individual cytokine-secreting T cells after being stimulated with a specific antigen. TigraTest SARS-CoV-2 Test assessing release of interferon gamma in vitro to detect peripheral blood T-lymphocytes that specifically respond to the SARS-CoV-2 virus antigens manufactured by GENERIUM JSC, is created on the ELISPOT platform. This study describes the procedure for laboratory validation of this test system to analyze the following parameters: specificity of antibody pair, effect of interfering substances, sensitivity and specificity, precision, stability of blood samples till isolation of target cells. The developed test system showed high diagnostic sensitivity and specificity. The specificity of TigraTest SARS-CoV-2 was 100%, the sensitivity for subjects immunized with the Gam-COVID-Vac vaccine (Sputnik V) was 91.67%, and the sensitivity in convalescent COVID-19 patients was 95.45%. At the same time, the data variability both during within and between series comparison did not exceed 25%, whereas 24-hour storage of peripheral blood samples at (1825)С after blood collection followed by isolation of target cells did not affect the test results.

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The disfunction or deficiency of the C1 esterase inhibitor (C1INH) is associated with hereditary or acquired angioedema (HAE/AAE), a rare life-threatening condition characterized by swelling in the skin, respiratory and gastrointestinal tracts. The current treatment options may carry the risks of either viral infection (plasma-derived Berinert®) or immune reaction (human recombinant C1INH from rabbit milk, Ruconest®). This study describes the physicochemical and biological characterization of a novel recombinant human C1 esterase inhibitor (rhC1INH) from Chinese hamster ovary (CHO) cells for the treatment of hereditary angioedema compared to the marketed products Berinert® and Ruconest®. The mass spectrometry results of total deglycosylated rhC1INH revealed a protein with a molecular mass of 52,846 Da. Almost full sequence coverage (98.6%) by nanoLC-MS/MS peptide mapping was achieved. The purity and C1s inhibitory activity of rhC1INH from CHO cells are comparable with Ruconest®, although we found differences in charge isoforms distribution, intact mass values, and N-glycans profile. Comparison of the specific activity (IC50 value) of the rhC1INH with human C1 esterase inhibitor from blood serum showed similar inhibitory properties. These data allow us to conclude that the novel rhC1INH molecule could become a potential therapeutic option for patients with HAE/AAE.