Development of a potential vaccine against dengue and chikungunya virus co-infection using immunoinformatics and structural evaluation.

Dengue virus (DENV) and chikungunya virus (CHIKV) co-infection poses a growing challenge in regions where both arboviruses co-circulate, highlighting the need for integrated vaccine strategies. Here, we designed a multi-epitope subunit vaccine candidate targeting conserved regions of the DENV NS1 protein and the CHIKV NSP1 protein using an immunoinformatics-based approach. Conserved CTL, HTL, and B-cell epitopes were selected on the basis of antigenicity, safety-related screening, and population coverage, then assembled with immunologically appropriate linkers and an N-terminal human β-defensin-2 adjuvant. The construct displayed favourable physicochemical features and acceptable structural quality after three-dimensional modeling and validation. Docking analysis indicated stable interaction with human TLR4, which was further examined by normal-mode analysis and 100-ns all-atom molecular dynamics simulations performed in AMBER v24 with the ff19SB force field. Trajectory analyses supported conformational stability of the vaccine-TLR4 complex, and MM/GBSA calculations suggested favourable binding energetics. Codon optimization supported expression feasibility in the E. coli pET-28a(+) system. In silico immune simulation further predicted induction of both humoral and cellular immune responses, with increased antibody production and immune-memory development. These results support the proposed construct as a rational candidate for further experimental evaluation toward a vaccine strategy against DENV-CHIKV co-infection.