Fig 4.
Functional interchangeability of ACT. (A) Toxin activity of ACT was measured by the production of cAMP. Bars represent pmol of cAMP per mg of protein of J774.1 macrophages, with solid bars representing supernatant-incubated cells and striped bars representing cells incubated with resuspended bacterial pellets. Asterisks indicate a statistically significant difference from wild-type bacteria and the complemented strain RB515::pDB505 (*, P < 0.05; **, P < 0.001; ***, P < 0.0001). icyaA, catalytically inactive cyaA gene. (B) BALB/c mice were inoculated intranasally with 50 μl of PBS containing 5 × 105 CFU of B. bronchiseptica strains as indicated, and the numbers of CFU in the right lungs were determined at 3 h, 72 h, and 11 days p.i. Each point represents the log CFU recovered from a single animal. Horizontal black lines show the mean for each group. Asterisks indicate a statistically significant difference from wild-type bacteria (*, P < 0.05; **, P < 0.001; ***, P < 0.0001).