Figure 2: PGH-PTD eradication of intracellular S. aureus in cultured cells.

Cultured cells were infected, treated with gentamicin to kill extracellular S. aureus, and then treated with the PGHs indicated. All results are standardized to the gentamicin (GENT) only control. Nomenclature of the PGH constructs is as in Fig. 1. PTDs are listed in Table 1. Asterisks indicate statistical significance detected with single factor ANOVA (α = 0.05) with paired t-test posthoc analyses α = 0.05 adjusted with Šidák correction for multiple comparisons (for all cases p < 0.01). (A) Bovine mammary epithelial cell line (MAC-T) infected with strain Newbould 305 (N = 8). Error bars represent SEM. 1-Sigma is commercial lysostaphin (Sigma). (B) Human brain microvasculature epithelial cells (hBMEC) infected with S. aureus strain ISP479C (N = 3). (C) Murine primary osteoblasts (mOB) infected with S. aureus strain UAMS-1 (N = 3). (D) Single plane of confocal microscopy z-stack overlaid on bright field exposure of live cultured MAC-T cells exposed to both S. aureus and PGH 3-PTD1. Live S. aureus (~0.6–1.0 μM diameter) are labeled with green fluorescent wheat germ agglutinin (WGA); PGH K-L-PTD1 is labeled with Alexa Fluor (Red). Yellow staining in the combined panel represents intracellular co-localization (in a single plane as determined by z-stack analysis) of both S. aureus and K-L-PTD1 (blue arrow). (E) Confocal microscopy maximum intensity projections (with all z-planes represented) of a MAC-T cell exposed to S. aureus and K-L-PTD1 as in (D) The majority of the S. aureus are localized in the thickest part of the cytoplasm surrounding the zone of exclusion created by the nucleus. Many, but not all, S. aureus are co-localized with K-L-PTD1 (yellow) in the combined panel.