Study on protective immunity induced by recombinant sars-cov-2 s1 and s protein vaccine

ABSTRACT

To evaluate the immune protection of recombinant SARS-CoV-2 S1 and S protein vaccine. Methods;Recombinant SARS-CoV-2 S1 or S protein combined with aluminum hydroxide adjuvant was inoculated at different doses of 0.1 μg, 1 μg, 5 μg and 10 μg per mouse for 6-8 weeks. Serum IgG antibody liters were detected by enzyme linked immunosorbent assay (ELISA) after second immunization. The serum neutralizing antibody titers of the immunized mice against pseudotype SARS-CoV-2-Fluc WT, B. 1.1. 7, P. 1, B. 1.617.2, B. 1.621, 501Y. V2-1 strains were compared by pseudovirus neutralization test. The cellular immune levels of sera were detected by enzyme-linked immunospot assay (ELISpot). Results;Both SARS-CoV-2 S and S1 proteins could induce strong IgG antibody levels in mouse model. The sera of mice immunized with S1 protein showed obvious neutralization activity against SARS-CoV-2-Fluc WT, B. 1. 1.7 and P. 1. The sera of mice immunized with the recombinant S protein also showed obvious neutralization activity against SARS-CoV-2-Fluc B. 1.617.2 in addition to SARS-CoV-2-Fluc WT, B. 1. 1.7 and P. 1. The serum of mice immunized with two kinds of proteins had the strongest neutralizing effect on SARS-CoV-2-Fluc WT. Mouse spleen cells immunized with S protein could significantly induce the production of interferon-γ (IFN--γ) and interleukin-4 (IL-4). The levels of IgG antibody, neutralizing antibody and cellular immunity induced by S protein were higher than those of S1. Conclusion;Recombinant SARS-CoV-2 S protein vaccine can induce protective immune responses. © 2022, China Biotechnology. All rights reserved.