Saponin inhibits HCV propagation by regulating SOCS2 gene.

<p>(A) Huh7.5 cells were treated with either negative or SOCS2 siRNAs. At 72 h after transfection, cell viability was analyzed by cytotoxicity assay. (B-D) Silencing of SOCS2 impairs inhibitory activity of saponin on HCV propagation. Huh7.5 cells were transfected with the indicated siRNAs. At 36 h after transfection, cells were infected with HCV Jc1 for 4 h and then treated with 10 µg/ml of saponin for 24 h. Total cell lysates were immunoblotted with the indicated antibodies (B). Both intracellular HCV RNAs (C) and extracellular HCV RNAs (D) isolated from the culture supernatant were quantified by qRT-PCR. (E, F) Overexpression of SOCS2 suppresses HCV replication. Huh7 cells were transfected with either empty vector or FLAG-tagged SOCS2 expression plasmid. At 24 h after transfection, cells were infected with HCV for 4 h. Cell lysates harvested at 48 h postinfection were immunoblotted with the indicated antibodies (E). (F) Huh7 cells were treated as described in the figure legend to E. Intracellular HCV RNAs were isolated and analyzed by qRT-PCR.