CASP8 and infection: As other immune biomarkers, the caspase family proteins such as caspase-1 and caspase-8 were found to be at higher levels in the infection-derived EVs at 48 h when compared to control-derived EVs, which could suggest that the apoptotic pathway is initially mediated by caspase-1 (Figure 6B and Supplementary Figure S2J, respectively) and caspase-8 pathways during CCoV infection of CRFK cells (Figure 6C and Supplementary S2K, respectively).