An infected host can quickly recognize an invading pathogen via germ-line-encoded pattern recognition receptors (PRRs) that detect microbe-associated molecular patterns (MAMPs) commonly expressed by many pathogens. Recognition of MAMPs by their corresponding receptor allows the host to initiate a rapid inflammatory response that can limit initial pathogen replication (Janeway and Medzhitov 2002). At least four different groups of PRRs have been described with varying cellular location and ligand specificity. Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) are membrane-associated, while RIG-I-like receptors (RLRs) and NOD-like receptors (NLRs) are found in the cytosol. Among the 13 known TLRs, only TLR5 and TLR11 exclusively recognize protein microbial ligands (Kawai and Akira 2010). TLR5 detects flagellin, a...