Cultures grown under virulence-inducing conditions in the presence of CLA exhibit reduced virulence gene expression. (A) tcpA::lacZ expression was significantly lowered upon the addition of 32, 64, and 128 μM CLA. (B) CT expression was significantly lowered upon the addition of 32, 64, and 128 μM CLA. Statistical significance was determined using Student's t test. *, P < 0.001.