PVM infection modulates IL-20 cytokines. (a) Il-19, Il-20, Il-24, Il-20ra and Il-20rb mRNA levels were evaluated by RT-qPCR in lung tissue at 9 and 12 dpi. Results were expressed as fold increase compared to Air mice exposed to PBS and using expression of hprt1 as a housekeeping gene. (b) Expression of IL-19, IL-20 and IL-24 was evaluated on lung sections by immunohistochemistry at 12 dpi in Air and CS mice. Scale bar = 50 µm. (c) Il-19, Il-20, and Il-24 protein level in BAL fluid and sera were analyzed by ELISA and expressed in pg/mL. Results were expressed as mean ± SEM. * p < 0.05, ** p < 0.01, *** p < 0.001 and **** p < 0.0001 correspond to virus effect (PVM vs PBS). # p < 0.05 corresponds to CS effect (CS vs. Air). Three independent experiments have been performed with 3–5 mice in each group per experiment.