The Edwardsiella piscicida thioredoxin-like protein inhibits ASK1-MAPKs signaling cascades to promote pathogenesis during infection
Fig 5
Trxlp promotes bacterial colonization in vivo.
(A) Schematic representation of the zebrafish larvae microinjection infection model. Zebrafish larvae were maintained in E3 medium for up to 8 days post-fertilization (dpf). Bacteria were microinjected into the yolk sac of zebrafish larvae at 3 dpf, and the survival, bacterial burden, and cytokine expression were analyzed. (B) Wild-type (WT) or ask1-MO zebrafish larvae were infected with EIB202, Δtrxlp, trxlp-complemented E. piscicida (50 CFUs/larvae), or PBS as a control, respectively. The survival of zebrafish larvae was monitored for 5 days. n = 50 fish per group. Data shown are from 3 representative experiments. ** p < 0.01. (C) The zebrafish larvae were infected as in Fig 5B and collected at the indicated post-infection time points, and homogenates were plated to determine the bacterial CFUs per larvae. n = 5 fish per group at each time point. Data are representative of at least 3 experiments. (D) The zebrafish larvae were infected as in Fig 5B, and mRNA levels of TNF-α and IL-10 in indicated zebrafish larvae infected with EIB202, Δtrxlp, or trxlp-complemented E. piscicida at indicated time points were determined by qRT-PCR. PBS-treated zebrafish was used as the control. Data (means ± SD) are representation of 3 experiments. * p < 0.05. (E) Diagram of Trxlp function during E. piscicida infection process. The novel virulence effector Trxlp targets and inhibits the phosphorylation of ASK1, thereby suppressing Erk1/2- and p38-MAPKs and inhibiting the expression of TNF-α and IL-10 during infection.