TLR7 and influenza: In mice, influenza infection is sensed by toll-like receptor 3 (TLR3), TLR7, retinoid acid-inducible gene I (RIG-I), melanoma differentiation associated protein 5 (MDA-5), and the NOD-like receptor family member NOD-, LRR- and pyrin domain-containing 3 (NLRP3) (14, 15).