Animals and immune challenge.

Miiuy croakers were obtained from Zhoushan Fisheries Research Institute. Fish were acclimated at 25°C for at least 6 weeks in a recirculating water tank system filled with air-pumped seawater before experiments. The challenge was performed as described previously (30, 51). Briefly, each miiuy croaker (about 50 g) was injected with 0.2 mL phosphate-buffered saline (PBS; control) or SCRV (multiplicity of infection [MOI] = 5) intraperitoneally. Afterward, fish were sacrificed at different time points, and the spleen and liver tissues were collected for RNA extraction. All animal experimental procedures were performed in accordance with the National Institutes of Health′s Guide for the Care and Use of Laboratory Animals (52), and the experimental protocols were approved by the Research Ethics Committee of Shanghai Ocean University (no. SHOU-DW-2018-047).