Listeria monocytogenes switches from dissemination to persistence by adopting a vacuolar lifestyle in epithelial cells
Fig 5
L. monocytogenes cycles from vacuolar to cytosolic stages during cell subculturing.
A. Experimental design of cell subculturing. (“d”: day). B-C. HepG2 cells containing EGDe-GFP bacteria entrapped in LisCVs were purified by FACS (B), plated and examined by microscopy 1h later (d3+1h, C). (C) GFP-positive bacteria (green) are present in LAMP1+ compartments (red) near nuclei (blue). Bar: 10 μm. D-E. The same cells were examined 8h (d3+8h) and 3 days later (d6). Micrographs show representative images of cells stained with Listeria antibodies (red), fluorescent phalloidin to label F-actin or LAMP1 antibodies (green) and DAPI (blue). Bar: 10 μm. The framed regions are shown at a higher magnification in the upper right corner. F. The same cells were examined after another cell passage and 1 day of growth (d7) and labeled with ActA antibodies, fluorescent phalloidin and DAPI. Bar: 10 μm. G. JEG3 cells were infected with Listeria EGDe and grown as in (A) up to d7. The overlay images show confocal micrographs of Listeria or F-actin (green), Listeria or LAMP1 (red) and DAPI (blue). Bacteria heavily replicated in the cytosol, were concentrated at the edge of the host cell and were associated with short actin tails. Bar: 10 μm. A magnified image of the region pointed by an arrow is shown on the right.