[Novel vector preS1-tp fusion protein effectively inhibits hepatitis B virus replication and cccDNA synthesis by mediating hepatitis B virus targeting sequence small interfering RNA].

To study the use of preS1-tp fusion protein as a novel vector to mediate the entry of small interfering RNA (siRNA) targeting the carboxy-terminal nuclear localization signal (NLS) region of hepatitis B virus (HBV) core protein into HBV-infected hepatocytes, and to further explore the HBV replication inhibition and covalently closed circular DNA synthesis. HepG2.2.15 cells expressing the human sodium taurocholate co-transporting polypeptide were established on the basis of lentivirus infection system. siRNA against HBV NLS region was designed and synthesized. PreS1-tp fusion protein expression and purification was observed to test its ability to cell entry and DNA binding. NLS siRNA were delivered into HepG2.2.15- sodium taurocholate co-transporting polypeptide cells by preS1-tp fusion protein as a vector to observe the effects of NLS siRNA on HBV replication and covalently closed circular DNA levels. Analysis of variance was used for comparison between multiple groups, and the measurement data differences between groups were analyzed by t-test. HepG2.2.15-sodium taurocholate co-transporting polypeptide cell line was successfully constructed. Screened synthetic HBV NLS siRNA had significantly inhibited HBV replication. The preS1-tp fusion protein was expressed and purified on a large-scale. The fusion protein as a vector for HBV NLS siRNA had targeted delivery. The result showed that the fusion protein had effectively targeted siRNA to Hepg2.2.15-sodium taurocholate co-transporting polypeptide cell, which not only had effectively inhibited the expression of HBV mRNA, HBsAg and HBeAg, but also had significantly reduced the levels of HBV DNA and covalently closed circular DNA. The preS1-tp fusion protein constructed in this study uses the dual functional characteristics of preS1 binding to hepatocyte HBV receptor, and tp binding to nucleic acids, and targets HBV NLS siRNA against HBV-infected cells and block rcDNA from being transported to nucleus. siRNA plays a role in inhibiting HBV replication and covalently close circular DNA synthesis, providing a new strategy for the treatment of chronic hepatitis B caused by HBV infection, and a new research perspective for the complete elimination of HBV from the body.