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Table 1: Pattern recognition receptors (PRRs), microbial-associated molecular patterns (MAMPs), and expression patterns (see, [3, 12, 14]).

PRRs Location MAMPs MAMPs Non Viral Ligands Viral Ligands TLRs TLR1 Cell membrane Lipopeptides TLR2 Cell membrane Di-/triacyl lipopeptide Virion (HSV) Peptidoglycan HA (Measles) Lipoteichoic acid (LTA) Zymosan Porins B and H proteins (HCMV) Lipoarabinomannan Phospholipomannan ENv (MMTV) Glucuronoxylomannan GPI-linked proteins Core, NS3 (HCV) Virion TLR3 Endosome membrane dsRNA RNA viruses LR4 Cell membrane Lipopolysaccharide (LPS) ENv protein (MMTV) Mannan Glucuronoxylomannan F protein (RSV) HSP Fibrinogen TLR5 Cell membrane Flagellin TLR6 Cell membrane Lipoprotein, LTA, others TLR7 Endosome membrane Synthetic ssRNA (e.g., imiquimod, resiquimod (R848) Influenza A, VSV TLR8 Endosome membrane Synthetic ssRNA (e.g.,imiquimod, resiquimod (R848) HIV TLR9 Endosome membrane CpG DNA Unmethylated DNA (HSV 1,2) Hemozoin MCMV Adenovirus Baculovirus (wild type) TLR10 Cell membrane Unknown TLR11 Cell membrane Profilin NLRs Nod1 Cytoplasmic Gram-negative peptidoglycan Nod2 Cytoplasmic Gram-negative and positive peptidoglycan IPAF Cytoplasmic Flagellin Viral RNA NALP3 Cytoplasmic RNA FPR Cell membrane Formylated peptides, ? FPRL 1-2 Cell membrane Formylated peptides, ? RIG-1 helicase Cytoplasmic Synthetic dsRNA HCV, -triphosphate Japanese encephalitis dsRNA RSV, Influenza A, EBV C-type lectins Cell membranes Fungal carbohydrates

Abbreviations: dsRNA: double-stranded RNA; EBV: Epstein-Barr virus; ECMV: encephalomyocarditis virus; GPI: glycosylphosphatidylinositol; HA: hemagglutinin; HCV: hepatitis C virus; HCMV: human cytomegalovirus; HIV: human immunodeficiency virus; HSP: heat-shock protein; HSV: herpes simplex virus; LPS: lipopolysaccharide; MCMV: murine cytomegalovirus; MMTV: mouse mammary tumor virus; RSV: respiratory syncytial virus; ssRNA: single-stranded RNA; VSV: vesicular stomatitis virus.