Fig. 4.

E-cadherin localization and Listeria invasion assays of placental explants. Shown are the results of Gram stains of tissue sections (A and B), immunohistochemical assays of E-cadherin (green) and bacterial (magenta) localization (C, D, and F), and the number of gentamicin-resistant viable bacteria (E) after incubation of explants with isogenic wild-type (EGD) (A–D) or InlA-deficient (ΔA) (F) strains of L. monocytogenes. (A and C) Findings obtained after a 1-h infection and a 2-h incubation with gentamicin. (B, D, and F) Representative results after a 1-h infection, followed by a 2-h incubation with gentamicin and a 21-h incubation in culture medium without antibiotics. The graph in E displays the relative level of infection after 3 and 24 h with either EGD or ΔA strains (mean values ± SD are plotted, n = 3 independent experiments, each done in quadruplicate). (Bars in A–D and F, 10 μm.)