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. Author manuscript; available in PMC: 2017 Jul 1.
Published in final edited form as: Mol Microbiol. 2016 May 27;101(1):42–61. doi: 10.1111/mmi.13367

Figure 9. The effect of prsA2 mutants of the secretion of known virulence determinants.

Figure 9

(A) Hemolytic activity of prsA2 mutants. Bacterial culture supernatant dilutions were assessed for the ability to lyse sheep red blood cells (RBCs) in vitro. The reciprocal of the dilution that resulted in 50% RBC lysis (hemolytic units) was determined for 4 independent experiments. (B) Phospholipase activity of the prsA2 mutants. Phospholipase activity was determined by the incubation of strains on Listeria selective agar plates containing lecithin that when hydrolyzed produces a zone of opacity surrounding the bacterial streak. (C) Intracellular growth and cell to cell spread of prsA2 mutants. A representative plaque assay is shown where monolayers of mouse L2 fibroblasts were infected with the indicated Lm strains and plaque formation was determined in the presence of gentamicin 72 hours post-infection. At least 25 plaques were measured in 3 independent experiments for all strains. Measurements represent plaque size with respect to Lm wt (set at 100%). Grey bars represent the reference strains and the variants are color-coded as Figure 4. Error bars represent the standard error of the mean where P≤0.05 by two-tailed Student’s T-test when compared to Lm wt as indicated by asterisks.