Construction of the expression vectors of HDV ribozymes and their intracellular inhibiting activity against HCV RNA / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To investigate whether HDV ribozymes can intracellularly inhibit HCV RNA.</p><p><b>METHODS</b>The mammalian expression vectors, pC1-RzC1, pC1-RzC2 and pC1-RzC3, containing ribozymes cDNA of RzC1, RzC2, and RzC3, were constructed targeting different HCV-5' NCR-C RNA regions. Then the HCV-positive fetal hepatocytes were transfected with these plasmids using liposome-mediated method. The inhibitory effects of HDV ribozymes were evaluated by HCV RNA quantitation in cultured cells and the supernatants.</p><p><b>RESULTS</b>(1) All the three HDV ribozymes were inserted into the expression vector. (2) Fetal hepatocytes were infected with HCV proven by RT-PCR and fluorescent quantitative PCR and expressed HCV NS3 and NS5 antigens by immunocytochemistry. (3) HDV ribozymes inhibited the activity of the target HCV RNA at expect positions in HCV-positive hepatocytes. At 0.5 micromol/L, the inhibitory rate of pC1-RzC1, pC1-RzC2, and pC1-RzC3 was 53.2%, 50.5 %, and 10.6% respectively. PC1-RzC1 was used continuously for one week, showing the inhibitory rate of 60.7%, 64.2%, 68.4%, 71.9%, 78.8% and 83.1% on the 2nd, 3rd, 4th, 5th, 6th and 7th day.</p><p><b>CONCLUSION</b>The inhibitory activity of pC1-RzC1 (107-113nt) and pC1-RzC2 (268-274nt) is greater than that of pC1-RzC3 (345-351nt) in HCV-positive hepatocytes.</p>

Design and activity assessment of HDV ribozymes to trans-cleave HCV RNA / 第三军医大学学报

Objective　To study the probability of using hepatitis D virus (HDV) ribozyme as a kind of anti-hepatitis-C-virus (HCV) gene thera-py drugs. Methods　The natural HDV genomic ribozyme′s stem Ⅳ was optimized and its substrate-binding region reconstructed, thus three recombinant HCV-specific HDV genomic ribozymes RzC1, RzC2 and RzC3 were obtained. HCV RNA 5'-noncoding region and 5'-fragment of C region (HCV RNA5'-NCR-C) were transcribed from plasmid pHCV-neo by T7 phage RNA polymerase in vitro, and radiolabelled at its 5'-end. The trans-cleaving reaction was performed by mixing the ribozymes and substrate at mol ratio 100∶1 under conditions as follows: 37℃, pH7.5, Mg2+ 20 mmol/L and deionized formamide 2.5 mol/L. Percentage of trans-cleaved products were calculated at different time points and used as the activity indicator of the three ribozymes. Results　RzC1, RzC2 trans-cleaved more substrate when the time extended, and got to 24.9%,20.3% after reac-ting for 90 minutes respectively; RzC3 was not able to trans-cleave its substrate. Conclusion　Recombinant HDV genomic ribozymes have the ability to trans-cleave HCV RNA, but the appropriate target sequence should be selected.

Design and activity assessment of HDV ribozymes to trans-cleave HCV RNA / 第三军医大学学报

Objective　To study the probability of using hepatitis D virus (HDV) ribozyme as a kind of anti-hepatitis-C-virus (HCV) gene thera-py drugs. Methods　The natural HDV genomic ribozyme′s stem Ⅳ was optimized and its substrate-binding region reconstructed, thus three recombinant HCV-specific HDV genomic ribozymes RzC1, RzC2 and RzC3 were obtained. HCV RNA 5'-noncoding region and 5'-fragment of C region (HCV RNA5'-NCR-C) were transcribed from plasmid pHCV-neo by T7 phage RNA polymerase in vitro, and radiolabelled at its 5'-end. The trans-cleaving reaction was performed by mixing the ribozymes and substrate at mol ratio 100∶1 under conditions as follows: 37℃, pH7.5, Mg2+ 20 mmol/L and deionized formamide 2.5 mol/L. Percentage of trans-cleaved products were calculated at different time points and used as the activity indicator of the three ribozymes. Results　RzC1, RzC2 trans-cleaved more substrate when the time extended, and got to 24.9%,20.3% after reac-ting for 90 minutes respectively; RzC3 was not able to trans-cleave its substrate. Conclusion　Recombinant HDV genomic ribozymes have the ability to trans-cleave HCV RNA, but the appropriate target sequence should be selected.