Figure 2.

Schematic representation of the key principles involved in innate immune recognition by host pattern recognition receptors (PRRs). Upon viral infection, viral pathogen-associated molecular patterns (PAMPs), such as the viral genome or gene products are recognized by several cellular PRRs present on the cell membrane, in the cytoplasm or within intracellular compartments. Sensing of PAMPs by PRR triggers PRR-mediated signaling pathways and activates antiviral responses, leading to subversion of the infection. Abnormal activation of PRRs may also trigger auto-immunity. Abbreviations: TLRs, Toll-like receptors; NLRs, nucleotide oligomerization domain (NOD)-like receptors; RLRs, retinoic acid-inducible gene I (RIG-I)-like receptors; IFN-α/β, type-I interferons α/β; CCLs/CXCLs, chemokine ligands; IL-1β/IL-18, inflammatory cytokines.