Fig. 7: In mouse bioassay, biofilm-isolated and planktonic L. monocytogenes with murinized InlA (InlA^m) display differential tissue distribution.

a PCR confirmation of the insertion of inlA^m gene in the chromosome of Lm F4244 ∆inlA using primers inlA.up.5 and inlA.down.3 (Supplementary Table 2). WT (F4244) was used as a positive control. b Immunoblots showing expression profile of InlA, and LAP in whole-cell extracts of WT, inlA^m, and ∆inlA. c ELISA showing the positive reaction of anti-InlA mAb to whole-cell preparation of WT, inlA^m, and reduced reaction with ∆inlA. d Percent invasion of WT, inlA^m, and ∆inlA to HCT-8 cells. Bars represent mean, and a pairwise Student’s t-test was used for statistical analysis. e Lm WT, inlA^m and ∆inlA strain burdens in the large intestine, MLN, spleen, and liver of mice (n = 5–6) 96 h after oral challenge (5 × 10⁹ CFU/mouse). Mann–Whitney test was used for statistical analysis. f Percent adhesion and invasion of biofilm-isolated and planktonic cells of InlA^m strain to HCT-8 cells. Bars represent mean, and a pairwise Student’s t-test was used for statistical analysis. g, h Lm burdens in tissues of mice (C57BL/6, male and female, 8–10 weeks old) challenged with murinized InlA^m (1 × 10⁹ CFU/mouse) strain of biofilm-isolated (B^M) or planktonic (P^M) cells at 24 (g) or 48 (h) hpi. Mice were pretreated with streptomycin (5 mg/ml) in drinking water for 32 h followed by 16 h in antibiotic-free water before the Lm challenge. i Comparison of tissue (spleen and liver) burden between WT and InlA^m strain for biofilm-isolated (B^WT vs B^M) and planktonic (P^WT vs P^M) cells at 48 hpi. Data for WT were taken from Fig. 5. Bars represent median values, and the Mann–Whitney test was used for statistical analysis in e, g, h. ****P < 0.0001; ***P < 0.0005; **P < 0.005; *P < 0.05; ns, no significance.