A novel therapeutic hepatitis B vaccine induces cellular and humoral immune responses and breaks tolerance in hepatitis B virus (HBV) transgenic mice
ABSTRACT Therapeutic vaccines are currently being developed for chronic hepatitis B and C. As an alternative to long-term antiviral treatment or to support only partially effective therapy, they should activate the patient's immune system effectively to fight and finally control the virus. A paradigm of therapeutic vaccination is the potent induction of T-cell responses against key viral antigens - besides activation of a humoral immune response. We have evaluated the potential of a novel vaccine formulation comprising particulate hepatitis B surface (HBsAg) and core antigen (HBcAg), and the saponin-based ISCOMATRIX™ adjuvant for its ability to stimulate T and B cell responses in C57BL/6 mice and its ability to break tolerance in syngeneic HBV transgenic (HBVtg) mice. In C57BL/6 mice, the vaccine induced multifunctional HBsAg- and HBcAg-specific CD8+ T cells detected by staining for IFNγ, TNFα and IL-2, as well as high antibody titers against both antigens. Vaccination of HBVtg animals induced potent HBsAg- and HBcAg-specific CD8+ T-cell responses in spleens and HBcAg-specific CD8+ T-cell responses in livers as well as anti-HBs seroconversion two weeks post injection. Vaccination further reduced HBcAg expression in livers of HBVtg mice without causing liver damage. In summary, this study demonstrates therapeutic efficacy of a novel vaccine formulation in a mouse model of immunotolerant, chronic HBV infection.
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ABSTRACT: Chronic hepatitis B (CHB) is a widespread infectious disease with unfavorable outcomes and life-threatening consequences for patients, in spite of modern vaccination and antiviral treatment modalities. Cutting-edge experimental approaches have demonstrated key pathways that involve cross-talk between viral particles and host immune cells. All events, including penetration of hepatitis B virus (HBV) particles into host cells, establishing persistence, and chronization of CHB infection, and possibility of complete elimination of HBV particles are controlled by the immune system. Researchers have paid special attention to the replication capacity of HBV in host cells, which is associated with cellular changes that reflect presentation of viral antigens and variability of HBV antigen features. In addition, specific HBV proteins have an immune-modulating ability to initiate molecular mechanisms that "avoid" control by the immune system. The relationship between immunological shifts and chronic infection stages has been intensively studied since it was recognized that the immune system is a direct participant in the recurrent (cyclic) nature of CHB. Understanding the wide diversity of molecular pathways and the crosstalk between innate and adaptive immune system components will provide fresh insight into CHB immune pathogenesis and the possibilities of developing new treatment strategies for this disease. KEYWORDS: Antiviral drugs; Chronic hepatitis B; Hepatocellular carcinoma; Immune response; ImmunopathogenesisWorld Journal of Gastroenterology 10/2014; 20(39):14156-14171. DOI:10.3748/wjg.v20.i39.14156 · 2.43 Impact Factor
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ABSTRACT: A mouse model for persistent HBV infection is essential for the development of a therapeutic vaccine against HBV. Because HBV cannot infect mouse hepatocytes, even if the HBV receptor is introduced, surrogate models are used. A suitable model needs to establish persistent HBV replication and must allow the establishment of HBV-specific adaptive cellular and humoral immune responses. Therefore, an immunocompetent mouse model is needed in which one can break HBV-specific tolerance and ideally eliminate the HBV transcription template. The most widely used model for chronic HBV infection is the HBV transgenic mouse. Although HBV replicates from an integrated transgene, HBV-specific immune tolerance can be broken upon adequate immune stimulation because antigen expression only starts shortly before birth. Alternative mouse models of chronic HBV infection are generated by introducing HBV genomes either using viral vectors or using hydrodynamic injection. In these alternative models, the HBV transcription template is introduced into a proportion of hepatocytes and stays extra-chromosomal. It thus mimics the natural HBV transcription template, the HBV cccDNA in humans. Unlike an HBV transgene, however, it can be cleared upon appropriate treatment or immune stimulation. Human hepatocyte chimeric mice in which murine hepatocytes are widely replaced by human hepatocytes represent another important mouse model for persistent HBV infection. These mice are susceptible for HBV infection, but need to be severely immune deficient to accept human hepatocytes. In conclusion, a variety of mouse models for persistent HBV infection are available suitable for preclinical efficacy evaluations of therapeutic vaccination strategies against HBV.Medical Microbiology and Immunology 12/2014; 204(1). DOI:10.1007/s00430-014-0378-6 · 2.43 Impact Factor
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ABSTRACT: To develop an effective, convenient and stable mucosal vaccine against hepatitis B virus (HBV), the mannose-PEG-cholesterol/lipid A-liposomes (MLLs) loaded with HBsAg were prepared by the procedure of emulsification-lyophilization and, subsequently, filled into the microholes of microneedle array reverse molds and dried to form the proHBsAg-MLLs microneedle arrays (proHMAs). The proHMAs were stable even at 40 °C for up to 3 days and hard enough to pierce porcine skin but, upon rehydration, rapidly dissolved recovering the HBsAg-MLLs without obvious changes in size and antigen association efficiency. Notably, immunization of mice only once with the proHMAs at oral mucosa induced robust systemic and widespread mucosal immunoresponses, as evidenced by the high levels of HBsAg-specific IgG in the sera and IgA in the salivary, intestinal and vaginal secretions. In addition, a strong cellular immunity against HBV had been established through a mixed Th1/Th2 response, as confirmed by a significant increase in CD8+ T cells as well as the enhanced levels of IgG2a and IFN-γ in the treated mice. Thus, the proHMAs can be conveniently vaccinated via oral mucosal route to set up a multiple immune defense against HBV invasion and, in addition, may be a stable HBV vaccine applicable in the controlled temperature chain for wide distribution.Colloids and surfaces B: Biointerfaces 01/2015; 126. DOI:10.1016/j.colsurfb.2015.01.005 · 4.29 Impact Factor