Enhanced protective efficacy of an OprF/PcrV bivalent DNA vaccine against Pseudomonas aeruginosa using a hydrogel delivery system

Pseudomonas aeruginosa (PA) is one of the leading pathogens responsible for hospital-acquired infections. With the increasing antibiotic resistance of PA, clinical treatment has become increasingly challenging. DNA vaccines represent a promising approach for combating PA infection. However, the immune response induced by a single antigen is limited, and combination vaccines hold greater therapeutic potential. The highly conserved OprF and PcrV genes are attractive candidate antigens for vaccine development, but the poor delivery of such vaccines has limited their clinical application. In this study, we constructed an OprF/PcrV bivalent DNA vaccine, and a polyaspartamide/polyethylene glycol di-aldehyde (PSIH/PEG DA) hydrogel was formulated to improve DNA delivery. The OprF/PcrV DNA vaccine formulated with the PSIH/PEG DA hydrogel was carefully characterized in vitro and in vivo and showed suitable compatibility. The PSIH/PEG DA hydrogel formulation induced a mixed Th1/Th2/Th17 immune response in mice, leading to a significant increase in antibody titers, lymphocyte proliferation rates, and cytokine levels compared to those in mice treated with single or combined vaccines. The PSIH/PEG DA hydrogel delivery system significantly enhanced the immune protection of the DNA vaccine in a murine pneumonia model, as revealed by the reduced bacterial burden and inflammation in the mouse lungs and increased survival rate. In conclusion, the PSIH/PEG DA hydrogel delivery system can further enhance the immune efficacy of the combination OprF/PcrV DNA vaccine. This research provides a novel optimized strategy for the prevention and treatment of PA infection using DNA vaccines.