FIG 4.

S. sonnei LPS-specific fecal IgA (A) and IgG (B) geometric mean ELISA endpoint titers with 95% confidence intervals prior to challenge (day −1) and 3, 7, and 14 days postchallenge, grouped by target dose of S. sonnei 53G: 500 CFU (cohort 1), 1,000 CFU (cohorts 2 and 3), and 1,500 CFU (cohorts 4 and 5). There were no significant differences in ELISA titers between any two dose groups at the same time point, as determined by 2-way ANOVA of log-transformed titers with a Bonferroni post hoc test.