Multivalent antibody responses in vivo. Mice were vaccinated with blank solution, heat-treated hSP, or nanotoxoid(hSP) on day 0 with boosts on days 7 and 14. On day 21, the serum was sampled and analyzed for the presence of IgG antibody titers against α-toxin (A), PVL (B), and γ-toxin (C) (n = 7; geometric mean). * p < 0.05, ** p < 0.01, **** p < 0.0001, one-way ANOVA.