PPARA and susceptibility to pneumonia measurement: The peroxisome proliferator-activated receptor (PPAR) α/γ-adenosine 5′-monophosphate- (AMP-) activated protein kinase- (AMPK-) sirtuin-1 (SIRT1) pathway and fatty acid metabolism are reported to be involved in influenza A virus (IAV) replication and IAV-pneumonia.