sentence: There was no evidence of genetic changes or strain contamination.Capsule polysaccharide expression in vivo was further explored by evaluating whether RNA transcripts from the cap operon could be detected in mouse blood following infection with a representative panel of USA300 ( two in vivo CP-positive isolates , PFESA0119 and PFESA0029 [ CDC3 ] and an in vivo CP-negative isolate , PFESA0021 ) and USA500 ( in vivo CP-positive isolate PFESA0065 ) isolates .