Second-generation COVID-19 vaccines should induce a long-term protective immune response against existing and new strains of SARS-CoV-2. The design of the Convacell® vaccine aims to generate such an immune response by using the N protein as an antigen. The N protein is not subject to rapid accumulation of mutations and has a high homology with nucleocapsid proteins of other β-coronaviruses. The purpose of this work was to conduct an in vitro trial of the Convacell® ability to induce an immune response against Wuhan, Delta and Omicron strains. Mononuclear cells of vaccinated or recovered volunteers were stimulated with N protein, which was followed by assessing the specific activation by flow cytometry. The results showed that a significant percentage of CD4+- and CD8+-cells produce IFNγ and IL2 in response to stimulation. No statistically significant decrease in response was found for the Delta and Omicron strains compared to the Wuhan strain. The results obtained support the direction in the design of N-protein vaccines for creating a universal vaccine.
Immunity, coronavirus, vaccine, SARS-CoV-2, new strains, N protein, nucleocapsid, Delta, Omicron, Wuhan