Mice were vaccinated and challenged as described in Fig. 1B and intestinal tissue collected one week post-challenge. Tissue sections were stained with antibodies specific for CD138, CD19, IgG, or IgA, followed by fluorescent secondary antibodies. Cells were counterstained with DAPI (blue). (A) IgG and IgA ASC lining the small intestine of YopB/LcrV+dmLT vaccinated and PBS mice post-challenge. Orange arrows signify CD138+CD19+ plasmablasts. White arrows on merge panels indicate co-localized staining for CD139, CD19, and IgG or IgA. (B) YopB- and LcrV-specific IgG and IgA in intestinal lavage fluid obtained one week after vaccination (pre-challenge) and after challenge. Data represent antibody titers (from 5 mice per group) normalized by total IgG or IgA content. Line shows arithmetic mean titers. Significant differences between vaccinated and control mice were determined by 2-way ANOVA with Tukey’s multiple comparisons; *, P<0.05 compared to PBS and **, P<0.05 compared to PBS and pre-challenge titer.