Effective inhibition of expression of hepatitis B virus genes by DNAzymes

AIM: To evaluate the inhibitory effects of DNAzymes on the expressions of hepatitis B virus (HBV) s (HBsAg) and e (HBeAg) in 2.2.15 cells, and to explore the potential therapeutic effects of DNAzymes on replication of HBV genome. METHODS: DNAzymes DrzBS and DrzBC specific to HBV (ayw subtype) s gene ORF A157UG and e gene ORF A1816UG, were designed and synthesized. Inhibitory effects of DrzBS or DrzBC on the expressions of HBV s and e genes as well as HBV DNA levels in culture supernatants were observed in 2.2.15 cells. RESULTS: After being treated with DrzBS or DrzBC, the expression of HBV s or e genes in 2.2.15 cells was depressed dramatically. The maximum inhibition rate was 94.2% and 91.8% for DrzBS and DrzBC, respectively. The concentration for effective inhibition of both DrzBS and DrzBC was within 0.1-2.5 µmol/L, showing a dose-dependence. The efficiency of inhibiting HBsAg, HBeAg in 2.2.15 cells by DrzBS or DrzBC was higher than that of the same target genes by antisense oligonucleotides (ASON). The concentration for effective inhibition of DNAzymes was at least 10-fold lower compared with ASON controls. Neither inhibition on the replication of HBV DNA nor toxicity to 2.2.15 cells was observed. CONCLUSION: DrzBS and DrzBC can block the expression of HBV s- and e-genes in 2.2.15 cells and provide a specific and effective anti-HBV gene therapeutic means.