Characterization of immune responses to a novel therapeutic vaccine for the treatment of chronic hepatitis B virus infections

HepaVaxx B, a Chimigen(TM) vaccine that can be used to treat chronic hepatitis B (HBV) infections, is a fusion protein of fragments HBV surface antigen and murine monoclonal antibody. BALB/c mice were immunized with HepaVaxx B without adjuvant and antigen-specific B and T cell responses were evaluated. There was a strong humoral immune response against the HBV antigen in mice treated with the vaccine compared to controls. In the majority of mice immunized with HepaVaxx B, there was an increase in IFN-gamma production in splenic T cell culture upon recall antigen stimulation ex vivo. Analysis of anti-HBV IgG2a/2b subclasses indicated that this vaccine induced Th1 immune response. Thus HepaVaxx B is a strong immunogen in the mouse and may be used as a therapeutic vaccine against chronic HBV infections.