ABSTRACT
A simple reproducible and versatile small animal model for hepatitis B virus (HBV) infection is still unavailable. We have generated a simple transient liver-targeted transgenic mouse. Hydrodynamics tail vein injection of a head-to-tail dimer of adw HBV genome (pHBVadwHTD) into immunocompetent mice generated HBsAg and HBeAg expression in both serum and hepatocytes, followed by seroconversion. The injection of pHBVadwHTD into SCID mice generated prolonged HBsAg and HBeAg antigenemia and HBV viremia. Our results demonstrate that hydrodynamic injection of naked DNA could support the generation of HBV particles. We used this model for the assessment of anti-viral agents. Administration of our human monoclonal antibodies, HBV-Ab17(XTL) and HBV-Ab19(XTL), as well as Lamivudine (3TC) treatment suppressed HBV viremia. The model presented herein supports long and stable expression of HBV and will enable determination of various biological questions related to HBV life cycle, mutants and could enhance the development of anti-viral reagents.
ABSTRACT
Current therapies for chronic hepatitis B virus (HBV) infection are limited in their effect on viral gene expression and replication. Recent reports have shown that RNA interference can be induced in mammalian cells by short interfering RNA duplexes (siRNA). Here we studied the effects of an HBV-specific 21-bp siRNA targeted to the surface antigen region (HBsAg), where three major viral mRNAs overlap, on HBV gene expression and replication both in a cell culture system and in a mouse model for HBV replication. Transfection of siRNA into HepG2.2.15 cells, which constitutively produce HBV particles, caused a significant reduction in viral RNA production that was accompanied by a >80% drop in the secretion of viral HBsAg and HBeAg into the medium. The effect of RNAi was tested in vivo in a mouse model that we have developed for HBV infection, which entails hydrodynamic injection of a plasmid bearing the HBV genome into tail veins of mice. Injection of the HBV plasmid induces viral replication and generation of HBV viral particles detectable in the mouse sera. Co-injection of the HBV plasmid together with siRNA caused a significant inhibition in the level of viral transcripts, viral antigens, and viral DNA detected in the livers and sera of the treated mice relative to control animals. Results suggest that siRNA is capable of inhibiting HBV replication in vivo and thus may constitute a new therapeutic strategy for HBV infection.
