Interferon-inducible ribonuclease ISG20 inhibits hepatitis B virus replication through directly binding to the epsilon stem-loop structure of viral RNA
HepDES19 cells were transfected with 100 nM of control siRNA (Lane 1–3) or ISG20 siRNA (siISG20) (lane 4–6) twice with a 24 h interval after tet being withdrawn. Culture medium was replaced 12 h after the 2nd siRNA transfection, and cells were either left untreated as controls (lane 1 &4) or treated with 100 IU/ml (lanes 2 & 5) or 1,000 IU/ml (lanes 3 & 6) of IFN-α. Cells were harvested 5 days after 2nd transfection. Viral total RNA (top panel), encapsidated pgRNA (upper middle panel), and core DNA (lower middle panel) were subjected to Northern and Southern analyses, respectively. ISG20 protein expression was revealed by Western blot, and β-actin served as loading control (bottom panels). The relative levels of viral nucleic acids and ISG20 expression in the siISG20 transfected or IFN-α treated samples (lanes 2–6) are expressed as the percentage of the control sample (lane 1). The data presented here are representative of two independent experiments.