Demonstration of specificity of in vivo CP immune responses in mice challenged with S. aureus isolates.

CP5 antibody titers in mice challenged with CP5 S. aureus isolates (MSSA strain Reynolds, two USA300 MRSA isolates PFESA0029 [CDC3] and PFESA0119, PFESA0119 Δcap5HIJK ermC capsule knock-out strains). CD1 mice (7–9 weeks of age, 10 per group) were administered three IP injections of ~ 2x106 CFU/animal in 0.5 mL at 0, 6 and 14 weeks, and bled two weeks after the final inoculation. CP5 antibody responses were measured using a CP5 specific cLIA assay. CP5 antibody responses were detected in mice infected with strain Reynolds, and PFESA0029 and PFESA0119 isolates, while the capsule knockout mutant was not able to induce a CP5 antibody response. GMT fold change over the antibody titer of the capsule knockout mutant was calculated for all tested isolates.