Development of Chimeric Hepatitis B (HBV) – Norovirus (NoV) P particle as candidate vaccine against Hepatitis B and norovirus infection

Introduction: Hepatitis B remains a global problem with no effective treatment. Here, a mucosal vaccine candidate was developed with HBsAg and HBcAg, to provide both prophylactic and therapeutic protection against hepatitis B. The antigens were presented using the P particle of human norovirus (HuNov). As a result, the chimeric HBV – HuNoV P particle can act as a dual vaccine for hepatitis B and HuNoV. Methods: The vaccine candidate was expressed and purified from Escherichia coli BL21 (DE3) cells. HBV-HuNoV chimeric P particles were successfully expressed and isolated, with sizes of approximately 25.64 nm. Then, the HBV-HuNoV chimeric P particles were evaluated for safety and immunogenicity in mice and gnotobiotic (Gn) pigs. After three doses (5 µg/dose in mice and 200 µg/dose in Gn pigs) of intranasal immunization, humoral and cellular immune responses, as well as toxicity, were evaluated. Results: The vaccine candidate induced strong HBV-HuNoV specific IFN-γ producing T-cell responses in the ileum, spleen, and blood of Gn pigs. Serum IgG and IgA antibodies against HBV-HuNoV chimeric P particles also increased significantly in Gn pigs. Increased HBsAg- and HuNoV-specific serum IgG responses were observed in mice and Gn pigs, although not statistically significant. The vaccine candidate did not show any toxicity in mice. Conclusions: In summary, the chimeric HBV-HuNoV P particle vaccine given intranasally was safe and induced strong cellular and humoral immune responses in Gn pig. Modifications to the vaccine structure and dosage need to be evaluated in future studies to further enhance immunogenicity and induce more balanced humoral and cellular responses.