Development of novel tetravalent peptide-based candidate dengue vaccine encapsulated in poly-lactic-co-glycolic acid nanoparticles to confer protection against all four dengue serotypes

Dengue virus comprises four serotypes (DENV1-4) and causes 390 million global infections with 500,000 hospitalizations and 250,000 deaths annually. The live attenuated CYD-TDV (Dengvaxia) is the only licensed vaccine but safety and efficacy is of concern. Multi-epitope based peptide vaccine carrying B and T cell epitopes is a novel vaccine platform. Identification and selection of potent B and T cell epitopes are crucial for rational vaccine design. B cell epitopes predicted from bioinformatics or recognized by potent cross-reactive monoclonal antibodies will be experimentally validated. The capability of each KLH-conjugated peptide specifying a B cell epitope in eliciting neutralizing antibodies will be evaluated by the Foci Reduction Neutralizing Test (FRNT). To identify the conserved CD4+ and CD8+ T cell epitopes against all four DENV serotypes, peptide pools consisting of 5 predicted peptides derived from C, E, NS2A, NS3, NS4B and NS5 proteins will be evaluated. IFN-γ production by the splenocytes stimulated with each peptide pool will be determined by ELISpot. The multifunctional T cell activities will be determined by the expressions of CD107a, IFN-γ, TNFα and IL-2 from CD4+ and CD8+ T cells by flow cytometry. These experiments will be carried out by using a murine model. Selection of B cell epitopes will be based on those expressing high levels of neutralizing antibodies while CD4+ and CD8+T cell epitopes will be selected based on high IFN-γ levels and CD107a expressions. Peptides representing potent B and T cell epitopes will be encapsulated in poly-lactic-co-glycolic acid (PLGA) nanoparticles to formulate a multi-epitope peptide-based dengue vaccine. The efficacy of PLGA encapsulated peptide vaccine to confer protection will be investigated in AG129 mice. This project will lead to the development of a tetravalent peptide-based nanovaccine that is protective against all four dengue serotypes.