Table 2.

Cytoplasmic pattern recognition receptors

Receptors and major ligands	Live infectious bacteria and virus	Leukocytes
NLR family
CARD subfamily
NOD1 GM-tripeptide; meso-lanthionine; meso-DAP;	Chlamydia spp.; enteroinvasive E. coli;	Monocytes; macrophages;
γ –D-Glu-DAP;	Helicobacter pylori; Listeria monocytogenes;	DCs*
FK156 (d-lactyl-l-ala-γ-Glu-meso-DAP-Gly);	Pseudomonas spp.; and Shigella flexneri
FK565 (Heptanoly-γ-Glu-meso-DAP-d-ala)
NOD2 M-TRILys (MurNAc-L-Ala-γ-d-Glu-l-Lys); MDP	L. monocytogenes; Salmonella flexneri;	Monocytes; mast cells; DCs;
	S. typhimurium; and Streptococcus pneumoniae	granulocytes
IPAF Bacterial flagellin from Coxiella, Legionella and Salmonella	S. typhimurium	Monocytes; macrophages; DCs; B cells
Pyrin subfamily (14 NALPs)
NALP1 LeTx (anthrax lethal toxin); MDP	Staphylococcus aureus and L. monocytogenes	Monocytes; DCs; B and T cells
NALP3 ATP; bacterial mRNA; maitotoxin; nigericin; uric acid crystal; R848		Monocytes; DCs; T cells
BIR subfamily
NAIP Flagellin from Bacillus, Legionella and Salmonella	Legionella pneumophila
		Macrophages
RNA helicases
RIG-1 Uncapped 5′-triphosphate-RNA	Newcastle disease virus, Sendai virus, influenza virus, vesicular stomatitis virus, Japanese encephalitis virus	Conventional DCs
MDA5 Encephalomyocarditis virus dsRNA; poly (I :C)	Encephalomyocarditis virus; picornaviruses; Thyler’s virus and Mengo virus	Conventional DCs

^*Non-leukocytes expressing NODs include epithelioid and fibroblastoid cells. dsRNA-dependent protein kinase (PKR) and R proteins are not listed [158].