Humoral and cellular immune response to a single dose of a novel bivalent recombinant adenovirus-vector vaccine against West Nile virus and chikungunya virus in mice.

Background: West Nile virus (WNV) and chikungunya virus (CHIKV) are zoonotic pathogens transmitted by mosquitoes, which cause significant morbidity and mortality globally. Currently, no human vaccine is available against both WNV and CHIKV.

Methods: In this study, we developed a novel bivalent recombinant human adenovirus type 5 (Ad5)-based vaccine, designated Ad5-WNV-CHIKV, which encodes WNV prM-E and CHIKV E3-E2-6 K-E1 antigens. The expression of the target antigens for WNV and CHIKV was validated through western blotting and an immunofluorescence assay. We subsequently assessed the humoral and cellular immune response in C57BL/6 mice following intramuscular administration of a single dose of Ad5-WNV-CHIKV.

Results: Both low-dose (2 × 10⁸ viral particles [vp] per mouse) and high-dose (1 × 10⁹ vp per mouse) administration of Ad5-WNV-CHIKV elicited robust immune responses against the viral targets, with specific immunoglobulin G production against WNV-E, CHIKV E1, and CHIKV E2 proteins, and generation of neutralizing antibodies against WNV and CHIKV, in a dose-dependent manner. Moreover, the vaccine induced strong cellular immunity, characterized by multifunctional antigen-reactive CD4⁺ and CD8⁺ T-cell populations, as determined by ELISpot and intracellular cytokine staining assays.

Conclusion: A single dose of the bivalent Ad5-WNV-CHIKV vaccine induced strong neutralizing antibody and cellular immune responses against both WNV and CHIKV in mice. These findings provide a foundation for the development of vaccines targeting WNV and CHIKV. A single dose of vaccine could potentially prevent both diseases.