Interferon-inducible ribonuclease ISG20 inhibits hepatitis B virus replication through directly binding to the epsilon stem-loop structure of viral RNA
HepG2 cells in 6-well-plate were co-transfected with 1 μg of pCMVHBVΔCΔP and 5 μg control vector (lane 1) or 1 μg of FLAG-Pol in the absence of HA-ISG20D94G (lane 2) or increased amount of HA-ISG20D94G (1 μg, 2 μg, 4 μg; lanes 3–5). The total amount of transfected DNA was kept constant (6 μg/well) by adding control vector plasmid (lanes 2–4). 5 days later, total cellular HBV RNA and protein (FLAG-Pol and HA-ISG20D94G) were determined by Northern and Western blot, respectively, as input controls (top panels). Immunoprecipitation was performed by using antibodies against HA or FLAG epitopes, followed by Northern blot analysis of HBV RNA (bottom panels).