SIRT4 and infection: Our results demonstrated that mitochondrial SIRT3 and SIRT4 protein expression increased from 12 and 24 h post infection (p.i.)onwards, respectively, whereas the nuclear SIRT1 expression increased during the first 12 h p.i. followed by a decrease after 36 h p.i., reaching the same level of control at 48 h p.i. Sirtuins interact with/and regulate the activity of FOXO family proteins, and we herein observed that FOXO3A and FOXO1 expression increased significantly and stably from 12 h p.i. onwards.