Probiotic-based oral vaccine mucosal delivery system enabling genetically encoded dual-antigen arrays

Oral vaccines provide a non-invasive approach for cancer immunotherapy but face challenges in gastrointestinal stability, antigen presentation, and mucosal delivery. Here, we present an engineered probiotic-based oral vaccine system, Bac^{OR-Fn-T+phiX174}, featuring genetically encoded dual-antigen ferritin arrays and inducible bacterial lysis. Upon oral administration and arabinose induction, the probiotic strain lyses in situ, releasing OVA/TRP2-decorated ferritin nanoparticles that efficiently traverse the intestinal barrier via M-cell targeting and activate mucosal dendritic cells. This platform robustly stimulates CD8⁺ and CD4⁺ T-cell responses, enhances B-cell and macrophage activation, reduces regulatory T cells, and provides therapeutic efficacy against melanoma in both lung metastasis and subcutaneous tumor models. It also establishes durable immunological memory without disrupting systemic or mucosal homeostasis. This work offers a programmable bacterial chassis for precise antigen array presentation and controlled delivery, representing a promising strategy for next-generation, needle-free cancer vaccines.