FIG. 3.

Recall antibody responses to i.n. priming with HEL+EtxB or HEL+CtxB. Mice were given two i.n. immunizations, 7 days apart, as described for Fig. 2. On day 22 after the first immunization, all mice were challenged i.n. with 1 μg of HEL plus 1 μg of Ctx. Ten days later, the mice were sacrificed and samples were obtained. Samples were assayed for HEL-specific antibody by ELISA. Data bars, mean antibody titers (error bars, SEM) (n = 3 mice per group). Fecal samples from all mice in each group were pooled to determine fecal antibody titers. ∗, P < 0.05 compared to equivalent dose of EtxB. (A) Serum anti-HEL IgG1; (B) fecal anti-HEL IgG1; (C) nasal anti-HEL IgG1; (D) serum anti-HEL IgA; (E) fecal anti-HEL IgA; (F) nasal anti-HEL IgA.