Fig. 1
Intranasal delivery of adjuvanted RBDXBB.1.5-HR vaccine elicits strong humoral immune response with great levels of neutralizing antibodies. a The schematic representation of the immunization and sera collection protocol in mice and rats. The animals were intranasally administrated with adjuvanted RBDXBB.1.5-HR on days 0, 21 and 42, and the sera were collected on day 14 after each immunization. b Endpoint titers of anti-RBD IgG in sera from mice intranasally immunized with low dose (5 μg) and high dose (10 μg) of adjuvanted RBDXBB.1.5-HR vaccine (n = 6 mice per group). c Endpoint titers of sera anti-RBD IgG in rats received 40 μg of intranasal RBDXBB.1.5-HR vaccine (n = 5 rats per group). d Antibody subtypes of anti-RBD IgG in mouse sera collected on day 56 (n = 6 mice per group). e Neutralizing antibodies against pseudoviruses in mouse sera collected on day 56 (n = 6 mice per group). Endpoint titers of anti-RBD IgA, IgG (f) and neutralizing antibodies (g) in mouse bronchoalveolar lavage fluid (BALF) sample that collected on day 72 (n = 6 mice per group). Data are presented as geometric mean values ± SD in b, and d–f, and presented as geometric mean with individual value in c. P values were conducted by One-way ANOVA analysis followed by Tukey’s multiple comparisons test in b, and d–g. ****P < 0.0001; ***P < 0.001; **P < 0.01; *P < 0.05; ns not significant
