Abstract: Objective To investigate the inhibitory effects of LNAzyme targeting the hepatitis C virus(HCV) 5′ non-coding region internal ribosome entry site(IRES) on HCV RNA replication and expression in cells. Methods The sequence encoding DNAzyme, thiolmodificated DNAzyme and LNAzyme targeting against the HCV IRES(located in the 5′ non-coding region) were designed and synthesized. The following experimental groups were set up: DNAzyme group, S-DNAzyme group, LNAzyme group, blank control group, empty liposomes group, random-LNAzyme group, and transfected by cationic liposomes into HepG2.9706 cells. The level of HCV RNA and luciferase gene expression of supernatant was tested by real-time fluorescent quantitative PCR and chemiluminescence technique at 24, 48 and 96 hours after treatment. LNAzyme’s cyto-toxicity on cell was evaluated by MTT method. Results Significant down-regulation of HCV RNA replication and luciferase gene expression was noted in the LNAzyme group when compared with other groups (all P<0.05). The average inhibition rates were 48.02% and 53.05%, respectively, and with the treatment time prolonged, the inhibition rate was increasing, 96 hours later, the average inhibition rates were 81.21% and 84.25%, respectively. There’s no obvious toxicity on cell. Conclusion LNAzyme has a significant inhibitory effect on HCV RNA replication and expression in vitrol, and was stronger than the thiolmodificated DNAzyme.

Key words: Hepatitis C, Hepatitis C virus, LNAzyme, Non-coding region, Gene regulation