Additionally, Toll-like receptor (TLR), p53 signaling, nucleotide oligomerization domain- (NOD-) like receptor, mitogen-activated protein kinase (MAPK), peroxisome proliferator-activated receptor (PPAR), and transforming growth factor-beta (TGF-beta) signaling pathways have been identified as essential players in immunity and host defense against pathogen infections. This evidence concerns the gene PPARA and infection.