TLR3 and infection: Innate sensing of HCV in hepatocytes occurs through the retinoic acid inducible gene-I (RIG-I) pathway before the onset of extensive viral protein synthesis, whereas toll-like receptor 3 (TLR3) functions as a secondary immune surveillance system by detecting viral RNA intermediates exposed either in endosomes or autophagic vesicles.[12] In agreement with this model, constitutively expressed RIG-I components, such as CARDIF and IKKε, were down-regulated at 24 h or at 48 h post-infection (Fig. 1A), respectively.