Immunogenicity of an Intranasal Dual (Core and Surface)-Antigen Vaccine Against Hepatitis B Virus Enhanced by Carboxyl-Vinyl Polymer Excipients.

Background: Hepatitis B virus (HBV) is a major cause of morbidity and mortality globally, and chronic infections are associated with cirrhosis and hepatocellular carcinoma. Issues with conventional treatments and vaccines mean there is a need for new therapeutic vaccines, which must elicit a strong and sustainable immune response. Here, we evaluated the immunogenicity of dual-antigen vaccines containing hybrid surface (hy-LHBs) and core (HBc) antigens, combined with a carboxyl-vinyl polymer (CVP) as a mucoadhesive excipient, following intranasal administration in mice. Methods: Mice were intranasally administered a mixed vaccine (10 µg of hy-LHBs and 2.5 or 10 µg of HBc) with or without a CVP excipient, and they were assessed for their immune response (levels of IgGs or IgA antibodies in an ELISA, IFN-γ level in splenocytes in an ELISpot assay, and cytokine/chemokine levels in a BioPlex assay). A protein stability assay was also conducted for vaccine formulations with and without excipients. Results: Significantly enhanced IgG production was noted targeting hy-LHBs and (less markedly) HBc at 10 µg/antigen, but only a non-significant elevation was noted with the vaccine containing 2.5 µg HBc. The BioPlex assay showed a significant increase in IL-2 (#00-07, 0B), IL-12(p40)(#00), eotaxin (#00), MIP1α (#00, #00-07, 0B), and MCP-1 (#00-07, 0B) in mice that received treatment compared to those of untreated mice. The endpoint titers of IgG1 and IgG2a were measured, which were higher with CVP excipients than without. From the IgG2a/IgG1 ratio, a higher IgG1 response was induced by CVPs to hy-LHBs and a higher IgG2a response was induced to HBc. Th2-dominant phenotype to hy-LHBs was induced with CVP#00 in an ELISpot assay. The highest anti-hy-LHBs antibody titer was noted with the conventional CVP#00 excipient. Consistent with these results, a higher amount of neutralizing antibodies of HBV was induced with CVP#00 treatment and followed by #00-03 and #14-00. Conclusions: We consider that the addition of CVP excipients to vaccine formulation enhances immunogenicity and HBV antigen stability for intranasal vaccines. This effect was seen for both humoral and cell-mediated immune responses, indicating the potential of CVPs as excipients in intranasal HBV vaccines.