FIGURE 3.

Effect of the deletion of saeRS, sa1804, or saeRS/sa1804 on the bacterial invasion of the human lung epithelial cell line (A549). Intracellular invasion was calculated as described in Section “Materials and Methods." Data are the means ± SE of the means from at least three repeated experiments. 923: wild type CA-MRSA control; sa1804: sa1804 deletion mutant; sa1804Com: sa1804 complementary strain; saeRS: saeRS deletion mutant; saeRS/sa1804: saeRS and sa1804 double deletion mutant. The symbol **represents P < 0.01 between wild type control and sa1804 knockout mutant.