FIG. 6.

IFN-induced inhibition of HCV RNA replication in HuH6 cells. (A and B) Antiviral effect of different IFN-α and IFN-γ concentrations. HuH6 Con1 replicon cells were seeded into multiple cell culture dishes, cultured for 24 h, and incubated with different IFN concentrations (0, 0.5, 1, 2.5, 5, 7.5, 10, 25, 50, and 100 IU/ml). After 72 h, total RNA was prepared and the number of HCV RNA copies was determined by quantitative, real-time RT-PCR. Mean values and standard deviations of six different quantifications are given. (C and D) Northern blot analysis of HCV RNA levels in IFN-treated HuH6 Con1 replicon cells and Huh-7 cells of clone 9-13. Cells were seeded into multiple cell culture dishes, cultivated for 24 h in normal culture serum, and further cultivated in the presence of 1,000-IU/ml IFN-γ. Total RNA was prepared at given time points, and 5-μg samples (lanes 1 to 5) were analyzed by using a riboprobe complementary to the neo gene (top) or to β-actin mRNAs (bottom). Different amounts of in vitro transcripts were used as standards (lanes 7 to 9). RNA isolated from naive cells served as a negative control (lane 6). The positions of