Experimentally investigated “CoronaDerm-PS”-driven SARS-CoV-2-specific cellular immunity and safety

Novel coronavirus disease 2019, caused by the SARS-CoV-2, initiate humoral and cellular immune responses against diverse virus antigens. The assessment of SARS-CoV-2-specific is mainly carried out in routine practice by determining specific immunoglobulins. However, high variability in S-protein structure in new genovariants of SARS-CoV-2 virus and the lack of correlation between specific antibodies and CD8+ T-lymphocytes underlie false negative responses, and mass assessment of cellular immunity is complicated due to the complexity of applying ELISPOT and cytofluorometry techniques. To solve this issue, a diagnostic method was developed for assessing SARS-CoV-2-specific cellular immune response, which is based on a skin test followed by evaluating a delayed-type hypersensitivity reaction involving antigen-specific memory T-lymphocytes. A diagnostic preparation CoronaDerm-PS is based on Cord_PS, which is a hybrid recombinant protein consisting of parts of the SARS-CoV-2 structural proteins S, M, N, E. The specific activity of this chimeric antigen was analyzed in cultured T-lymphocyte activation test by assessing interferon-γ production using cytofluorometry. To investigate the chimeric antigen specific activity, a preclinical safety study with CoronaDerm-PS preparation in experimental animals was conducted. A dose-dependent developing skin reaction was observed in 90–100% of guinea pigs vaccinated by EpiVacCorona, CoviVac, Gam-COVID-Vac, which confirms a potential for assessing post-vaccination cellular immunity using CoronaDerm-PS preparation. Upon this, the presence of functionally active T-cell-antigenic epitopes in the recombinant polypeptide allows to evaluate SARS-CoV-2-specific response illustrated by detected response after Gam-COVID-Vac (S-protein) and EpiVacCorona (N-protein) vaccination. Thus, a skin test based on CoronaDerm-PS preparation may be a promising diagnostic tool for rapid mass screening requiring no specialized laboratory equipment for assessing populational SARS-CoV-2-specific immunity. Such a test is distinguished by advantages such as ease of analysis, high specificity and sensitivity. The final decision-making on using this test in a real-world practice may achieved after conducting further clinical safety and effectiveness trials.