Figure 2.

Infection of THP-1 cells with prostate isolate P. acnes P6. (a) THP-1 cells were infected with P. acnes P6 at an MOI of 25. Infection was stopped after 2, 6, and 24 h. Cells were fixed with 4% PFA, and extracellular bacteria were stained with mouse polyclonal anti-P. acnes antibody and Cy-2 labelled goat-anti-mouse antibody (green). After permeabilization, intracellular bacteria were stained with mouse polyclonal anti-P. acnes antibody and Cy-3 labelled goat-anti-mouse antibody (red). Overlay of both stainings indicates extracellular bacteria (appearing yellow). Actin was stained with Alexa Fluor 647 phalloidin (blue). (b) and (c) Zoom-in on intracellular P. acnes (red) at 24 h p.i.