SIRT1 and infection: In particular, AMPK is downregulated during early infection, whereas afterwards (4 h after infection) the levels of AMPK and the phosphorylation of acetyl-CoA carboxylase (one of its substrates) gradually recover; on the other hand, the levels of Sirt1 increase, suggesting that the virus-induced modulation of the AMPK/Sirt1 axis occurs differentially during the infection [34].