Plant-expressed Fc-fusion protein tetravalent dengue vaccine with inherent adjuvant properties.

Dengue is a major global disease requiring improved treatment and prevention strategies. The recently licensed Sanofi-Pasteur Denvaxia vaccine does not protect children under the age of nine and additional vaccine strategies are thus needed to halt this expanding global epidemic. Here, we employed a molecular engineering approach and plant-expression to produce a humanised and highly immunogenic Poly-Immunoglobulin G Scaffold (PIGS) fused to the consensus dengue envelope protein III domain (cEDIII). The immunogenicity of this IgG Fc receptor targeted vaccine candidate was demonstrated in transgenic mice expressing human FcγRI/CD64, by induction of neutralising antibodies and evidence of cell-mediated immunity. Furthermore, these molecules were able to prime immune cells from human adenoid/tonsillar tissue ex vivo as evidenced by antigen-specific CD4+ and CD8+ T cell proliferation, IFN-γ and antibody production. The purified polymeric fraction of dengue PIGS (D-PIGS) induced stronger immune activation than the monomeric form, suggesting a more efficient interaction with the low affinity Fcγ receptors on antigen-presenting cells. These results show that the plant-expressed D-PIGS have the potential for translation towards a safe and easily scalable single antigen based tetravalent dengue vaccine. This article is protected by copyright. All rights reserved