THP-1, A549 and HepG2 were infected with FITC-tagged and EU-labeled wt and hly-
L. monocytogenes for the indicated duration. Cells were then fixed, stained with Alexa594-azide and counterstained with DAPI. Left column, wt L. monocytogenes infection 1 hr. Middle column, wt L. monocytogenes infection 4 hrs. Right column, hly-
L. monocytogenes infection 4 hrs. A: THP-1 cells. B: A549 cells. C: HepG2 cells. As determined by counting of single bacteria in cells (50 cells per slide were counted) the average bacterial load was 9(wt) and 4(hly-) bacteria per cell for THP-1 cells, 6(wt) and 4(hly-) bacteria per cell for A549 cells and 6(wt) and 5(hly-) bacteria per cell for HepG2 cells, one representative experiment out of two is shown. Whole L. monocytogenes are labeled green with FITC and RNA is visible as red fluorescence (Alexa594), nuclei are stained by DAPI (blue).