Interferon-inducible ribonuclease ISG20 inhibits hepatitis B virus replication through directly binding to the epsilon stem-loop structure of viral RNA
HepG2 cells were co-transfected with plasmid pCMVHBVΔCΔP and either control vector (lane 1) or FLAG-Pol (lanes 2&3), or pCMVHBV with either control vector (lane 4) or F-ISG20D94G (lanes 5&6). Cells were harvested 4 days post-transfection. Input HBV RNA was determined by Northern blot (top panels). Input FLAG-Pol and F-ISG20D94G proteins were determined by Western blot using FLAG Ab (top panels). Cell lysates were immunoprecipitated with beads coated with FLAG Ab, the immunoprecipitated Pol and ISG20D94G were revealed by Western blot using FLAG Ab (lanes 3&6, bottom panel), and the bound RNA was extracted by Trizol and analyzed by Northern blot (lanes 3&6, bottom panel). HA Ab pull-down served as negative controls (lanes 2 & 5, bottom panel). See Material and Methods for more experimental details.