Single-dose dual-indication nanoparticle vaccine co-displaying Pseudomonas aeruginosa antigen and tetanus toxin fragment confers durable protection against mixed exposure.

Trauma, disaster, and conflict-related injuries can create clinically important co-exposure to Pseudomonas aeruginosa (PA) and tetanus toxin, where disrupted barriers and contaminated wounds enable simultaneous bacterial infection and toxin entry. Until now no licensed PA vaccine exists and multi-dose schedules are difficult to complete in emergency settings, thus a single-dose, dual-indication vaccine that provides rapid and durable protection is urgently needed. Here, we engineered and characterized a lumazine synthase (LS) nanoparticle vaccine (rePO-TTFC@LS) that co-displays a PA antigen (rePO; PcrV-OprI fusion) and tetanus toxin fragment C (TTFC). In BALB/c mice, rePO-TTFC@LS enhanced antigen uptake and dendritic-cell activation relative to soluble antigens. After a single intramuscular immunization, rePO-TTFC@LS elicited rapid, high anti-rePO and anti-TTFC IgG responses together with increased IFN-γ/IL-4/IL-17A-secreting splenocytes. Vaccination reduced lung bacterial burden and pulmonary IL-1β/IL-6 and improved survival and clinical outcomes in an acute PA pneumonia model, which provided complete protection against lethal tetanus toxin challenge, and decreased PA colonization with improved survival in a femoral fracture-implant co-infection model. Elevated antibody titers and dual protection persisted to 28 weeks after one dose, and biosafety assessments showed no meaningful hemolysis or cytotoxicity and no abnormalities in hematology/serum biochemistry or multiorgan histopathology. Collectively, these results support rePO-TTFC@LS as a single-dose, durable dual-indication nanoparticle vaccine and highlight a modular strategy for combination vaccines suited to mixed-exposure emergency scenarios.