FIG 4.

Single-cell analysis of cytosolic and vacuolar replication. HeLa epithelial cells (left), C2BBe1 epithelial cells (middle), or J774A.1 macrophage-like cells (right) were infected with wild-type (WT) S. Typhimurium strain SL1344 or deletion mutants harboring pFPV-mCherry. At 8 h p.i., monolayers were fixed, and the number of bacteria in each infected cell was scored by fluorescence microscopy. Each dot represents data for one infected cell, and data from three independent experiments were combined (≥150 cells in total). For HeLa and C2BBe1 cells, cells with ≥100 bacteria/cell contain cytosolic S. Typhimurium. Values at the bottom of all panels indicate the mean numbers of vacuolar bacteria per cell. Top and bottom asterisks in each panel indicate cytosolic and vacuolar replication significantly different from those of the wild type, respectively.