Deletion of graRS leads to attenuated virulence in a mouse infection model 
To investigate the impact of reduced resistance of the graRS mutant to neutrophil and CAMP-mediated killing on the ability of the bacteria to cause infections in vivo, we compared the virulence of WT and mutant bacteria in a mouse challenge model.
Therefore female BALB/c mice (12 to 15 weeks old) were infected with S. aureus WT or graRS mutant bacteria.
72 h after infection numbers of CFU/kidney were determined.
Significantly less bacteria were detected in the kidneys of animals, which had been infected with the graRS mutant than those infected with the WT bacteria.
(Fig. 3) This finding is in coincidence with the increased susceptibility to clearance by CAMPs and neutrophils, corroborating the central importance of these host factors in innate defense.
