FIG 5.

Protective efficacy of S. flexneri 2a OPS-IpaB conjugate vaccine. (A and B) Mice were immunized, as described in the Fig. 4 legend, and challenged i.n. with a lethal dose (5 × 10⁶ CFU) of S. flexneri 2a (A) or S. sonnei (B) on day 57 postvaccination. Data represent survival curves from 20 mice/group. P values determined by log rank (Mantel-Cox) test. (C and D) Comparison of vaccine-induced prechallenge IpaB- or S. flexneri 2a OPS-specific serum IgG titers between protected and nonprotected mice after S. flexneri 2a (C) and S. sonnei (D) challenges. Mean of individual titers ± standard error of the mean; *, P < 0.05 by t test. sl Sf2a-IN, sublethal dose of S. flexneri 2a-IN; sl SsM-IN, sublethal dose of S. sonnei Moseley-IN.