Listeria monocytogenes Invades the Epithelial Junctions at Sites of Cell Extrusion
Figure 2
Internalin A–Dependent Apical Adhesion and Invasion of Polarized Epithelia
(A and B) Polarized MDCK monolayers were infected from the apical side with Wt, ΔinlA, or ΔinlB L. monocytogenes.
(A) Invasion was determined by quantification of viable CFUs of intracellular bacteria after gentamicin treatment. Means and standard deviations from quadruplicate samples are shown. Sample groups are significantly different: one-way analysis of variance p < 0.0001; Bonferroni t- test p < 0.001 for all pairwise analyses.
(B) Adhesion after 10 min of infection. Means and standard deviations of the number of L. monocytogenes adhered per 1,000 cells from triplicate samples are shown.
(C) Confocal microscopy visualization of Wt L. monocytogenes adhered to a monolayer stained with antibodies to L. monocytogenes (green) and ZO-1 (red). Bacteria are found only at multicellular junctions and are conspicuously absent elsewhere.
(D) A higher magnification area demonstrating concentrated adhesion at a multicellular junction. Scale bars 10 μm.