Efficacy of Multivalent Dengue Vaccine Candidates Predicted In Silico

Background: Dengue virus (DENV) is becoming a global public health problem, but the immunogenicity of DENV structural proteins is not fully understood. Methods: We predicted the epitope-based immunogenicity of DENV proteins from four serotypes in silico and evaluated their efficacy in vitro (T-cell proliferation assays) and in vivo (ELISpot, qRT-PCR, and plaque reduction neutralization tests using murine splenocytes). We focused on the envelope protein, which contains envelope domain III. Immunogenic B-cell epitopes were predicted using BepiPred-2.0, and regions that induce T cell-mediated immune responses were analyzed using the immune epitope database (IEDB), which validates peptides presented on HLA class I. Results: Nine-amino-acid peptide candidates were selected based on a score of >0.1. The best peptide candidates were tested in T-cell proliferation assays to confirm the in silico data. Subsequently, BALB/c mice were vaccinated with candidate peptides showing immunity in the proliferation assay, and their splenocytes were analyzed. ELISpot and qRT-PCR data showed that some candidate peptides highly regulated cytokines, including interferon-γ, tumor necrosis factor-α, and interleukin-4. Murine sera were collected after peptide boosting 2 weeks apart. Stimulation of cellular immunity was confirmed for some candidates in plaque reduction neutralization tests.