Two Distinct Coagulase-Dependent Barriers Protect Staphylococcus aureus from Neutrophils in a Three Dimensional in vitro Infection Model (original) (raw)
Figure 8
The pseudocapsule is an additional protective barrier.
The pseudocapsules of vWbp emp double mutant microcolonies were protective against direct invasion of neutrophils into the microcolony (A, single frame from Video S6, 5 h after neutrophil challenge). After punctual rupture of the pseudocapsule, phagocytosis is initiated (B, single frame from Video S6, 27 min after A). After pseudocapsule rupture, phagocytosis is a rapid event (C, single frame from Video S7, 5 h after neutrophil challenge). USA300 barriers fulfill similar functions (D, single frame from Video S15, 3.5–5 h after neutrophil challenge). Direct contact of staphylococci with neutrophils led to massive neutrophil cell lysis/necrosis, visualized by Sytox Blue staining (yellow arrowheads, E–H, single frames from Video S8, 5 h after neutrophil challenge). In E, the microcolony outline is illustrated by a dotted line. Green: GFP-neutrophils; Blue: Sytox Blue-stained DNA; White: confocal reflection microscopy showing collagen fibers. Scale bar 20 µm.