Fig. 4.

Intracellular bacteriolysis of lysozyme-sensitive L. monocytogenes. Immunofluorescence microscopy of wt (A) or LysM⁻ (B) BMM infected with Pgd⁻ Oat⁻ L. monocytogenes (green) imaged at 90 min postinfection (actin and nuclei were stained red and blue, respectively). Insets depict bacterial degradation. Size bars represent 10 μm. Cytosolic DNA delivery is increased in Pgd⁻ and Pgd⁻ Oat⁻ L. monocytogenes strains (C). IFN-α/βR⁻ BMM were infected with L. monocytogenes bearing a plasmid-containing luciferase under a CMV promoter at an MOI of 5. Luciferase expression was detected at 6 h postinfection. Error bars represent standard deviations of the means determined in triplicate. Statistical significance was evaluated using Student's t test. Data are representative of at least 3 separate experiments with similar results. *, P < 0.01; **, P < 0.0001.