Abstract
Background: In this pre-clinical study, we designed a candidate vaccine based on severe acute respiratory syndrome-related -coronavirus 2 (SARS-CoV-2) antigens and evaluated its safety and immunogenicity.
Methods: SARS-CoV-2 recombinant protein antigens, including truncated spike protein (SS1, lacking the N-terminal domain of S1), receptor-binding domain (RBD), and nucleoprotein (N) were used. Immunization program was performed via injection of RBD, SS1 +RBD, and SS1 +N along with different adjuvants, Alum, AS03, and Montanide at doses of 0, 40, 80, and 120 μg at three-time points in mice, rabbits, and primates. The humoral and cellular immunity were analyzed by ELISA, VNT, splenocyte cytokine assay, and flow cytometry.
Results: The candidate vaccine produced strong IgG antibody titers at doses of 80 and 120 μg on days 35 and 42. Even though AS03 and Montanide produced high-titer antibodies compared to Alum adjuvant, these sera did not neutralize the virus. Strong virus neutralization was recorded during immunization with SS1 +RBD and RBD with Alum. AS03 and Montanide showed a strong humoral and cellular immunity; however, Alum showed mild to moderate cellular responses. Ultimately, no cytotoxicity and pathologic change were observed.
Conclusion: These findings strongly suggest that RBD with Alum adjuvant is highly immunogenic as a potential vaccine.
Keywords: COVID-19; Immunogenicity; Receptor binding domain; SARS-CoV-2; Subunit vaccine.
【저자키워드】 COVID-19, SARS-CoV-2, immunogenicity, Receptor binding domain, Subunit vaccine., 【초록키워드】 Vaccine, immunogenicity, antibody, cytotoxicity, adjuvants, cytokine, virus, immunization, flow cytometry, ELISA, Spike protein, Receptor binding domain, Antigen, Severe acute respiratory syndrome, IgG antibody, Receptor-binding domain, cellular immunity, mice, RBD, sera, Virus neutralization, Mild, Subunit vaccine, nucleoprotein, respiratory, moderate, Antibody titers, humoral and cellular immunity, binding, N-terminal domain, cellular, dose, Cytometry, alum, humoral, AS03, Cellular responses, IgG antibody titer, mild to moderate, acute respiratory syndrome, immunization program, domain, injection, candidate vaccine, immunogenic, doses, primates, alum adjuvant, protein antigens, VNT, produced, analyzed, pathologic, evaluated, was performed, were used, Strong, not neutralize, was recorded, 【제목키워드】 animal model, nucleocapsid protein, Protein, vaccine candidate, preclinical study, the spike protein,