Inhibition of HBV Replication by VPS4B and Its Dominant Negative Mutant VPS4B-K180Q In Vivo

This study examined the anti-hepatitis B virus （HBV） effect of wild-type （WT） vacuolar protein sorting 4B （VPS4B） and its dominant negative （DN） mutant VPS4B-K180Q in vivo in order to further explore the relationship between HBV and the host cellular factor VPS4. VPS4B gene was amplified from Huh7 cells by RT-PCR and cloned into the eukaryotic expression vector pXF3H. Then, the VPS4B plasmid and the VPS4B-K180Q mutation plasmid were constructed by using the overlap extension PCR site-directed mutagenesis technique. VPS4B and HBV vectors were co-delivered into mice by the hydrodynamic tail-vein injection to establish HBV vector-based models. Quantities of HBsAg and HBeAg in the mouse sera were determined by ElectroChemiLuminescence （ECL）. HBV DNA in sera was measured by real-time quantitative PCR. Southern blot analysis was used to assay the intracellular HBV nuclear capsid-related DNA, real-time quantitative PCR to detect the HBV-related mRNA and immunohistochemical staining to observe the HBcAg expression in the mouse liver tissues. Our results showed that VPS4B and its mutant VPS4B-K180Q could decrease the levels of serum HBsAg, HBeAg and HBV-DNA. In addition, the HBV DNA replication and the mRNA level of HBV in the liver tissues of treated mice could be suppressed by VPS4B and VPS4B-K180Q. It was also found that VPS4B and VPS4B-K180Q had an ability to inhibit core antigen expression in the infected mouse liver. Furthermore, the anti-HBV effect of mutant VPS4B-K180Q was more potent than that of wild-type VPS4B. Taken together, it was concluded that VPS4B and its DN mutant VPS4B-K180Q have anti-HBV effect in vivo, which helps develop molecular therapeutic strategies for HBV infection.