TLR3 (Toll-like Receptor 3) is a member of the TLR (Toll-like receptor) family that plays a fundamental role in pathogen recognition and activation of innate immunity. TLR3 consist of pathogen-binding ECDs (Ectodomains) and cytoplasmic signaling domains, known as TIR (Toll IL-1 Receptor) domains, joined by a single transmembrane helix. TLR3 is a nucleotide-sensing TLR, activated by double-stranded RNA (dsRNA) which is associated with viral infection. Additional to dsRNA it binds also to synthetic ligands mimicking dsRNA (such as Poly I:C). It acts via the adapter TRIF/TICAM1 and induces the activation of IRF3, ultimately inducing the production of type I interferons (IFNs). It has been demonstrated extensively that TLR3 activation leads to cross-priming of CD8+ T cells via major histocompatibility complex I for the generation of cytotoxic T cell (CTL) responses. TLR3 displays a protective role in mouse models of atherosclerosis and against brain ischemia.