Figure 2. Formation of PS⁺ structures during Lm infection.

A. HeLa cells were infected at an MOI of 100 with wild type Lm expressing RFP (red) for 6 h and then incubated with a probe for exofacial PS (Annexin V-Alexa 488; green). Cells were then fixed and analyzed by fluorescence microscopy to identify PS⁺ structures and Lm (right panel). Scanning electron microscopy of the same cell shows PS⁺ structures (left panel). Images representative of 2 independent experiments. Scale bars, 5 μm. B. Confocal images of cells infected with the indicated strain for 6 h. Boxed areas in left hand low mag image (a 3 color merge, includes phalloidin stain for F-actin) are enlarged to right. Arrows indicate Lm that colocalize with PS and arrowhead indicates PS⁺ filaments. Images representative of 3 independent experiments. Scale bars,10 μm for low mag merge, and 3 μm for enlarged panels. C. Cells containing PS⁺ bacteria enumerated for B. Averages +/− s.d. for 3 independent experiments. P values calculated using one-Way ANOVA. **P <0.01 ***P <0.001.