Figure 4. HCV PAMP RNA triggers the hepatic innate immune response and anti-HCV defenses.

a–f, Wild-type or RIG-I^−/− mice (n = 3) were hyrdrodynamically transfected intravenously with HCV RNA. a, mice received 100 μg of HCV 1b genome, HCV 1b genome lacking the 3’NTR (HCV 1b Δ 3’NTR), PU/UC RNA or X region RNA. Hepatic IFN-β mRNA expression was measured 8 hrs later. b–f, Wild-type or RIG-I ^−/− mice (n = 3) received 200 μg of poly-U/UC RNA or buffer control, and were sacrificed 4, 8 or 24 h later for comparative measurement of mRNA and protein expression. b, Liver-specific expression of IFN-β mRNA. c, Serum IFN-β protein levels. d, Liver-specific expression of RIG-I mRNA. e, Liver-specific expression of ISG56 mRNA. f, Immunohistochemcial stain of ISG56 protein expression in liver tissue sections. g and h, Paracrine antiviral effect of the innate immune response triggered by HCV PAMP RNA. g, Inhibition of HCV infection in pretreated cells. Triplicate cultures of Huh7.5 cells were treated with IFN-β or conditioned media collected from Huh7 cells transfected with the indicated RNA species for 12 h prior to HCV infection. The graph shows the number of infected cells (±SD) as determined by focus forming unit (FFU) assay at 48 h postinfection. h, Huh7.5 cells were infected with HCV for 48 h and then were treated with increasing concentrations of IFN-β or the indicated conditioned media for an additional 48 h. Intracellular HCV RNA levels relative to GAPDH were determined and are plotted as mean HCV RNA index (±SD) relative to infected, untreated cells.