Fig. 4.

IL-22 expression in PBL at 24 h after A. salmonicida infection. Rainbow trout were infected by i. p. injection of A. salmonicida (AS), or PBS as control. Blood samples were collected 24 h post challenge (hpc) and PBL prepared. PBL were immunostained with anti-IL-22 mAb L8 and analysed by flow cytometry, or used for total RNA preparation for RT-qPCR analysis of IL-22 transcript expression. Representative results are shown in (A) Gating of the leucocyte population and (B) Gating of IL-22⁺ cells. The isotope control staining is provided in Fig. S6B. (C) The percentage of IL-22⁺ cells in total leucocytes (mean +SE, N = 6). (D) Relative expression of IL-22 transcripts in PBL quantified by RT-qPCR (mean +SE, N = 6). The relative expression was first normalized against EF-1α, and presented as a fold change calculated as the average expression level of infected fish divided by that of the control fish. * indicates a significant difference between control and infected fish (p ≤ 0.05, independent samples T-test).