Phagocytosis killing assays and a PMN lysis assay with different <i>S. aureus</i> strains.

<p>(A) and (B) Survival of wild-type <i>S. aureus</i> strain HG001 and strain Newman (WT), and their isogenic <i>rsh_Syn</i> mutants, complementation strains (compl), <i>psmα</i>, <i>psmβ</i> double mutants (HG001), <i>rsh_Syn</i>, <i>psmα</i>, <i>psmβ</i> triple mutants (HG001), <i>agr</i> mutant (HG001) and <i>rsh_Syn</i>, <i>agr</i> double mutant (HG001) were determined after phagosomal uptake by counting colony-forming units after 60 min incubation. Bacterial cells used for the experiment were harvested at similar points of growth at an OD₆₀₀ of 1.0. The levels of significance were determined by the two-tailed Student t test (p<0.05). (C) Complementation of survival of the <i>rsh_Syn</i> mutant with tetracycline inducible <i>psmα</i> and <i>psmβ</i>. Therefore membrane permeable anhydrotetracycline (ATc) 0.1 µg/ml was used to induce <i>psm</i> expression after phagosomal uptake of the bacteria. The levels of significance were determined by the two-tailed Student t test (p<0.05). (D) Lysis of PMNs, as measured by release of lactate dehydrogenase (LDH) activity. PMN lysis was determined after a phagocytotic interaction of 60 min with <i>S. aureus</i> strain HG001 wild-type, corresponding <i>rsh_Syn</i> mutant, <i>agr</i> mutant and <i>rsh_Syn</i>, <i>agr</i> double mutant. As a positive control 2% TritonX were used. The levels of significance were determined by the two-tailed Student t test (p<0.05).