Growth of AA100, the ΔrtxA mutant (ΔrtxA), and ΔrtxA transformed with pJDC20, pJDC35, and pJDC40 in THP-1 cells over 48 h. Data points and error bars represent the mean number of CFU present at 48 h/number of CFU present at time zero (mean CFU Tx/T0) of triplicate samples from a representative experiment and their standard deviations, respectively. All experiments were performed at least three times.