FIG 1.

Differential immune response of O. niloticus is associated with the consequence of E. tarda infection. (A) Determination of the lethal dose of E. tarda to O. niloticus. O. niloticus fish were infected with either 0.8 × 10⁸, 1.6 × 10⁸, or 3.2 × 10⁸ CFU/fish. Cumulative fish death was monitored for a total of 14 days. (B) qRT-PCR to quantify cytokine expression in head kidneys of control, dying, or surviving fish 48 h postinfection. All of the statistical analyses were performed with Mann-Whitney U test unless otherwise indicated. *, P < 0.05; **, P < 0.01. Error bars represent means ± standard errors of the means (SEM) from at least three biological replicates. All of the experiments were repeated at least three times.