Evaluation of antiviral - passive - active immunization (“sandwich”) therapeutic strategy for functional cure of chronic hepatitis B in mice

BACKGROUND: Chronic Hepatitis B (CHB) remains a major problem for global public health. Viral persistence and immune defects are the two major reasons for CHB, and it was hypothesized that based on a transient clearance of serum viral DNA and HBsAg “window stage”, active immunization against hepatitis B virus (HBV) might initiate effective host immune responses versus HBV to achieve functional cure of CHB. METHODS: Two experimental mouse models that mice hydrodynamic injected HBV DNA or infected with recombinant AAV/HBV were used. The “sandwich” therapeutic effect by using a potent human anti-HBsAg neutralizing monoclonal antibody (G12) in combination with antiviral drug tenofovir disoproxil fumarate (TDF), followed by active immunization with HBsAg-HBsAb (mYIC) was evaluated. FINDINGS: A single G12 injection rapidly cleared serum HBsAg in HDI-HBV carrier mice, with a synergistic effect in decreasing viral DNA load when TDF was given orally. When both serum viral DNA and HBsAg load became low or undetectable, mYIC was administered. A more effective clearance of viral DNA and HBsAg was observed and serum HBsAb was developed only in these “sandwich”-treated mice. Efficient intrahepatic anti-HBV immune responses were also observed in these mice, including the formation of aggregates of myeloid cells with CD8(+)T cells and increased TNF-α, granzyme B production. INTERPRETATION: The “sandwich” combination therapy not only efficiently decreased HBsAg and HBV DNA levels but also induced effective cellular and humoral immunity, which may result in functional cure of CHB.