Figure 4.

Sal4 SIgA blocks STm entry into Peyer’s patches. (A) Schematic of the STm infection model. BALB/c female mice are orally administered Sal4 or isotype control antibody in PBS immediately prior to a 1:1 mixture of AR04 and AR05 STm strains (∼4 × 10⁷ CFUs). Twenty-four hours later mice are sacrificed, and a laparotomy is performed to isolate Peyer’s patches from the small intestine. Peyer’s patches from each mouse are pooled in 1 mL of ice-cold sterile PBS, homogenized, and plated for CFUs on LB agar containing kanamycin and X-gal. (B–D) STm invasion into Peyer’s patches of mice treated with (B) 50 μg of Sal4 mIgA, dIgA, or SIgA, (C) 10 μg of Sal4 mIgA or dIgA, or (D) 50 μg of IgG at the time of the STm challenge. Shown are the combined results of two separate experiments with at least 4 mice per group. Statistical significance was assessed by one-way ANOVA followed by Tukey’s post hoc multiple comparisons test.