Therapeutic vaccination strategy targeting the PreS1 region of L-HBsAg for HBV/HDV co-infection.

BACKGROUND & AIMS: Achieving functional cure for chronic hepatitis B (CHB) will likely require a combinatorial approach targeting multiple aspects of the complex hepatitis B virus (HBV) life cycle and host adaptive immune responses. Here, we developed a therapeutic vaccination strategy targeting the PreS1 region of L-HBsAg, required for cellular entry of both hepatitis B and D viruses. METHODS: An established potent T-cell inducing platform, recombinant adenovirus (Ad), was used as a nanoparticle scaffold for PreS1 attachment, to generate antibodies that neutralize virus entry and to establish T-cell mediated immune control. Ad particles encoding multiple HBV antigens were decorated with PreS1 peptide using DogTag/DogCatcher protein superglue. Immunogenicity of PreS1-decorated Ad was assessed in C57B/6 mice by IgG ELISA, serum neutralization assays, interferon-gamma ELISPOT, and intracellular cytokine staining. RESULTS: Screening a cohort of 61 patients diagnosed with CHB revealed minimal evidence of natural anti-PreS1 responses. Mice vaccinated with PreS1-decorated Ad induced robust anti-PreS1 antibody responses that neutralized HBV (p <0.01) and HDV (p <0.05) infection. In contrast, an undecorated Ad encoding L-HBsAg failed to neutralize HBV, demonstrating that PreS1 decoration was required for potent HBV neutralization. Strong CD8+ and CD4+ T-cell responses were induced against HBV antigens encoded in the Ad genome. CONCLUSIONS: PreS1-decorated Ad combines immunological HBV and HDV entry inhibition with potent anti-HBV T-cell induction in a single platform, providing a promising addition to current therapeutic strategies against CHB, with particular utility in HBV/HDV co-infection. IMPACT AND IMPLICATIONS: A functional cure for chronic hepatitis B is urgently needed, and given the complexity of the disease, achieving this will likely require combination therapies that target multiple stages of the viral lifecycle. Here we developed a therapeutic vaccination strategy that combines PreS1-targeted entry inhibition with induction of T-cell responses against multiple HBV antigens by decorating adenovirus particles encoding L-HBsAg and HBcAg with PreS1 peptide. In mice, PreS1-decorated adenovirus particles induced serum neutralizing activity against both HBV and HDV and robust T-cell responses against encoded HBV antigens. Our findings suggest that PreS1-decorated adenoviral vaccines could complement existing therapeutic approaches for viral hepatitis.