Fig. 3: Addition of TLR agonists to emulsion adjuvants boosts the spike-specific antibody titers, increases the ratio of IgG2c to IgG1, and promotes cross-recognition of variants.

A Serum antibody IgG titers against recombinant Wuhan-Hu-1 spike protein at 21 days after booster vaccination. B The mean AUC value for IgG2c was divided by that of IgG1 for each group. C Serum antibody IgG titers against recombinant spike RBD from the indicated virus. D Control ELISA against his-tagged neuraminidase (NA) from influenza A virus (IAV); dotted line indicates the limit of detection. Differences between groups were analyzed by one-way ANOVA with multiple comparisons by Tukey post-test. Asterisks denote significant differences versus unadjuvanted spike antigen and # indicate differences between other, indicated groups. */#p < 0.05, ##p < 0.01, ***/###p < 0.001, ****/####p < 0.0001.