Table 2.
PRR ligands.
| PRR | Location | Ligands | Signaling | Reference |
|---|---|---|---|---|
| TLR 3 | Endosome | long dsRNA (minimum length 40–50 bp); poly (I:C) | TRIF-dependent | [34] |
| TLR 7 | Endosome | ssRNA with preference for 3-mers with U located in second position | MyD88-dependent | [107] |
| TLR 8 | Endosome | ssRNA with preference for UG dinucleotides | MyD88-dependent | [34] |
| TLR 9 | Endosome | non-methylated CpG DNA; spherical nucleic acids containing CpG motifs | MyD88-dependent | [58,108] |
| RIG-I | Cytosol | short dsRNA and ssRNA with 5′-triphosphate; circRNA | MAVS-dependent | [43,49] |
| MDA5 | Cytosol | long dsRNA; poly (I:C) | MAVS-dependent | [43,109] |