SIRT4 and infection: In conclusion, our results support the notion that the up-regulation of TRAIL may be a primary mediator of CCoV-II-induced apoptosis, and that the mitochondrion plays a critical role in a host defense mechanism showing an involvement of SIRT (precisely SIRT3 and SIRT4) and FOXO families proteins in this infection, in part due to activation of both extrinsic and intrinsic apoptosis pathway.