Effect of trxHEp mutation on cellular infection and replication. A The invasion of Edwardsiella piscicida to flounder gill cells (FG cells). FG cells were infected with the same dose of TX01, TX01∆trxH, and TX01∆trxHC for various hours and washed with PBS. Then FG cells were lysed and the bacterial associated with and invaded into the host cells were determined. B FG cells were incubated with FITC-labeled E. piscicida TX01∆trxH or TX01, and the fluorescence of extracellular bacteria was quenched by adding trypan blue, then cells were observed with a confocal microscope. C Replication of E. piscicida in mouse macrophage cell RAW264.7. RAW264.7 cells were hatched with TX01, TX01∆trxH, and TX01∆trxHC for 2 h, then extracellular bacteria were killed. The cells were then incubated further for various hours, and the number of intracellular bacteria was determined by plate counting. Data are the means of three independent experiments and presented as mean ± SEM (N = 3). N, the number of times the experiment was performed. **P < 0.01.