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. Author manuscript; available in PMC: 2015 Dec 1.
Published in final edited form as: Int J Infect Dis. 2014 Nov 5;0:259–267. doi: 10.1016/j.ijid.2014.10.015

Figure 4.

Figure 4

Toll-like receptor (TLR), nucleotide-binding oligomerization domain (NOD)-like receptor (NLR), and retinoic acid-inducible gene (RIG-I)-like receptor (RLR) signaling. TLR1 or TLR2 or TLR6 recognizes lipoproteins, TLR3 recognizes dsRNA, TLR4 recognizes bacterial lipopolysaccharide (LPS), TLR5 recognizes bacterial flagellin, TLR7/8 mediates recognition of ssRNA. TLR9 acts as a DNA sensor and recognizes CpG DNA of bacteria and viruses. The NLR proteins NOD1 and NOD2 are cytosolic pattern recognition receptors (PRRs). NOD1 senses intracellular meso-diaminopimelic acid (DAP), whereas NOD2 recognizes muramyl dipeptide (MDP). C-type lectin receptor (CLR) signaling senses carbohydrate recognition domains (CRDs), or structurally similar C-type lectin-like domains (CTLDs). The RLR pathway is involved in the recognition of viral dsRNA. TLR, NLR, CLR, and RLR signaling causes activation of NF-κB, leading to the production of proinflammatory cytokines and the stimulation of immune responses.