Asymptomatic SSP mice show a robust type 1 inflammatory response in the colon at 28 dpi. (A) Schematic representation of the experimental design. F1 mice (129X1/SvJ × C57BL/6; n = 10) were infected with Salmonella Typhimurium SL1344 (10⁸ CFUs; STm) and treated with streptomycin (5 mg) at 14 dpi to induce the SSP state. (B) Percentage of body change variation of F1-uninfected (black circle) and F1-SSP (green circle) mice after streptomycin treatment at 14 dpi (n= 10). (C and D) Frequency and numbers of CD4⁺ and CD8α⁺ T cells isolated from the colonic lamina propria (cLP) of F1-uninfected (black circle) and F1-SSP (green circle) mice at 28 dpi (n = 5–10). (E) Frequency and numbers of Th1 cells isolated from the colonic lamina propria of uninfected (black circle) and SSP (green circle) mice at 28 dpi (n = 5–10). (F) Frequency and numbers of Th1 cells isolated from the spleen of uninfected (black triangle) and SSP (green triangle) mice at 28 dpi (n = 5–10). (G) Representative FACS plots and frequency of IFN-γ–producing CD4⁺ T cells (top) and CD8α⁺ T cells (bottom) isolated from the colonic lamina propria of F1-uninfected and F1-SSP mice at 28 dpi (n = 5–10). (H) Representative FACS plots and frequency of IFN-γ–producing CD4⁺ T cells (top) and CD8α⁺ T cells (bottom) isolated from the spleen of F1-uninfected and F1-SSP mice at 28 dpi (n = 5–10). (I) Representative FACS plots and frequency of tetramer⁺ (2W:I-A^b) CD4⁺ T cells isolated from the colonic lamina propria (circle) and spleen (triangle) of F1-uninfected and F1-SSP mice at 28 dpi (n = 5–10). Results are representative of at least two independent experiments and presented as means ± SEM. Normality was assessed by the D’Agostino–Pearson test. Two-way ANOVA (A) followed by post hoc Sidak’s test was performed for multiple comparisons. The Mann–Whitney U (C–I) test was used to compare two groups (****P < 0.0001; ***P < 0.001; **P < 0.01; ns = not significant). See also Figs. S1 and S2.