Known PAMPs include lipopolysaccharide (LPS) from the outer membrane of Gram-negative bacteria, peptidoglycan (present in most bacteria), lipoteichoic acid (in many Gram-positive bacteria), bacterial DNA, viral DNA/RNA and mannans in the yeast cell wall. PAMPs are recognized by pattern recognition receptors (PRRs), in particular Toll-like receptors (TLRs) and Nod-like receptors (NLRs), leading to an infl ammatory response via several signaling pathways, including nuclear factorkappa B (NF-κB) activation and subsequent tumor necrosis factor (TNF)-α production.