AIM To investigate the potential effect of curcumin on hepatitis B virus(HBV) covalently closed circular DNA(ccc DNA) and the underlying mechanism.METHODS A Hep G2.2.15 cell line stably transfected with HBV was treated with curcumin, and HBV surface antigen(HBs Ag) and e antigen(HBe Ag) expression levels were assessed by ELISA. Intracellular HBV DNA replication intermediates and ccc DNA were detected by Southern blot and real-time PCR, respectively. The acetylation levels of histones H3 and H4 were measured by Western blot. H3/H4-bound ccc DNA was detected by chromatin immunoprecipitation(Ch IP) assays. The deacetylase inhibitors trichostatin A and sodium butyrate were used to study the mechanism of action for curcumin. Additionally, short interfering RNAs(si RNAs) targeting HBV were tested along with curcumin.RESULTS Curcumin treatment led to time-and dose-dependent reductions in HBs Ag and HBe Ag expression and significant reductions in intracellular HBV DNA replication intermediates and HBV ccc DNA. After treatment with 20 μmol/L curcumin for 2 d, HBs Ag and ccc DNA levels in Hep G2.2.15 cells were reduced by up to 57.7%(P < 0.01) and 75.5%(P < 0.01), respectively, compared with levels in non-treated cells. Meanwhile, time-and dose-dependent reductions in the histone H3 acetylation levels were also detected upon treatment with curcumin, accompanied by reductions in H3-and H4-bound ccc DNA. Furthermore, the deacetylase inhibitors trichostatin A and sodium butyrate could block the effects of curcumin. Additionally, transfection of si RNAs targeting HBV enhanced the inhibitory effects of curcumin.CONCLUSION Curcumin inhibits HBV gene replication via downregulation of ccc DNA-bound histone acetylation and has the potential to be developed as a ccc DNA-targeting antiviral agent for hepatitis B. AIM To investigate the potential effect of curcumin on hepatitis B virus (HBV) covalently closed circular DNA (ccc DNA) and the underlying mechanism. METHODS A Hep G2.2.15 cell line stably transfected with HBV was treated with curcumin, and HBV surface antigen ( HBsAg) and e antigen (HBeAg) expression levels were assessed by ELISA. Intracellular HBV DNA replication intermediates and ccc DNA were detected by Southern blot and real-time PCR, respectively. The acetylation levels of histones H3 and H4 were measured by Western blot. H3 / H4-bound ccc DNA was detected by chromatin immunoprecipitation (Ch IP) assays. The deacetylase inhibitors trichostatin A and sodium butyrate were used to study the mechanism of action for curcumin. Additionally, short interfering RNAs (si RNAs) targeting HBV were tested along with curcumin.RESULTS Curcumin treatment led to time-and dose-dependent reductions in HBs Ag and HBe Ag expression and significant reductions in intracellular HBV DNA replication intermediates After treatment with 20 μmol / L curcumin for 2 d, HBs Ag and ccc DNA levels in Hep G2.2.15 cells were reduced by up to 57.7% (P <0.01) and 75.5% (P <0.01), respectively respectively, compared with levels in non-treated cells. Meanwhile, time-and dose-dependent reductions in the histone H3 acetylation levels were also detected upon treatment with curcumin, accompanied by reductions in H3-and H4-bound ccc DNA. deacetylase inhibitors trichostatin A and sodium butyrate could block the effects of curcumin. Additionally, transfection of si RNAs targeting HBV enhanced the inhibitory effects of curcumin. CONCLUSION Curcumin inhibits HBV gene replication via downregulation of ccc DNA-bound histone acetylation and has the potential to be developed as a ccc DNA-targeting antiviral agent for hepatitis B