TLR7 is a 1049aa long highly conserved membrane protein belonging to the Toll-like receptor (TLR) family with 27 LRR (leucine-rich) repeats and a TIR domain. It plays a fundamental role in pathogen recognition and activation of innate immunity. TLR7 is activated by infections with single-stranded RNA viruses, including influenza virus and vesicular stomatitis virus (VSV). It is predominantly expressed in lung, placenta, and spleen, and lies in close proximity to another family member, TLR8. It acts via MyD88 and TRAF6, leading to NF-kappaB activation, cytokine secretion and the inflammatory response. They recognize pathogen-associated molecular patterns (PAMPs) that are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity.