Preclinical investigation of intranasal adjuvanted COVID-19 vaccine

The researchers observed antibodies against the S1 and NC antigens in all the animals except those controlled negatively. However, the serological responses varied significantly. Serum IgG titers were significantly elevated in mice receiving vaccines with N3 adjuvant and exhibited nearly a 10-fold increase, and increasing the concentration of anionic L3 to 2% resulted in comparable antibody titers. A similar trend was observed only after the second vaccination for IgA titers, nearly 10-fold higher than the first dose. Microneutralizing antibody titers differed variably across mice receiving different vaccine doses. Mice in groups 5 (1 µg dose + N3 adjuvant) and 6 (0.1 µg + N3 adjuvant) exhibited significantly higher antibody titers. At the same time, those with L3 adjuvants had higher antibody titers than the positive control group. All immunized mice produced IgA antibodies against the SARS-CoV-2 antigens in the respiratory and gastrointestinal tracts.