Fig 6.

TNF-α induction during systemic S. aureus infection in TNFR1-deficient mice. Groups of C57BL6 (wild-type) and tnfr1^−/− mice were inoculated intraperitoneally with wild-type S. aureus (A and B) or the spa-deficient mutant (A), and 4 h later, TNF-α levels in serum were quantified by ELISA. Each symbol represents an individual mouse, and horizontal lines show the median value for each group. Asterisks indicate significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.001) by the Mann-Whitney test for nonparametric data.