DRibbles elicited HBV-specific protective immune response. The schematic diagram outlines the experiment protocol (A). The optimal dose of HBV+ DRibbles was determined by ELISPOT assay (n = 3). Lymphocytes from mice received HBV+ DRibbles generated a high number of IFN-γ secreting cells in 2 × 105 lymphocytes (B,C). Vaccinated mice were injected hydrodynamically with 10 μg of HBV plasmid DNA (n = 5) 7 days later. The serum HBV DNA (D) and HBeAg (E) was determined by real-time PCR and ELISA. Intrahepatic HBcAg was visualized by immunohistochemical staining (×200) (F). Results represent three independent experiments.