Ectopic expression of POLK rescues HBV infection in POLK deficient HepG2-NTCP cells.

(A) Expression of POLK in parental HepG2-NTCP and HepG2-NTCP^polk-/- cells transduced with lentivirus expressing wild-type POLK or empty vector were determined by Western blot analysis. GAPDH served as a loading control. POLK-1# and POLK-2# are two clones expressing exogenous POLK in HepG2-NTCP^polk-/- cells. (B-D) Parental HepG2-NTCP and HepG2-NTCP^polk-/- cells transduced with lentivirus expressing wild-type POLK or empty vector were infected by HBV. HBV cccDNA in the infected cultures on 7 dpi were detected by Southern blot analysis. The intensity of HBV cccDNA bands were determined by Image J and the relative amounts of cccDNA were expressed as the percentage of that in the infected parental HepG2-NTCP cells (B). HBcAg in the infected cultures on 7 dpi was detected by immunostaining with 1C10 mcAb (red). Cell nuclei were stained with DAPI (blue) (C). Scale bars, 50 μm. Secreted HBeAg from the infected cultures at 3, 5, 7 dpi were determined by ELISA (D).