Manganese Pyrophosphate Mineralized DNA Nanovaccine Elicits Potent Humoral and Cellular Immunity

Subunit vaccines offer safety and precision but require adjuvants to overcome weak immunogenicity, particularly for the induction of cellular immunity. Herein, we develop a manganese pyrophosphate mineralized DNA bi-adjuvant-based subunit vaccine platform via biomineralization, which demonstrated the capability to elicit robust antigen-specific cellular immune responses. The Mn/CpG bi-adjuvant modulated the balance between Th1 and Th2 immune responses. More importantly, the synergistic activation of Toll-like receptor 9-like (TLR9) signaling pathways by CpG and cGAS-STING pathways mediated by Mn(II) ions robustly enhanced cellular immunity, which was a magnitude of enhancement over commercial aluminum-based adjuvants both in vitro and in vivo. Furthermore, the mechanistic studies revealed that the Mn(II)-based nanoadjuvant effectively promoted Th1-biased cellular immune response, as evidenced by an elevated IgG2a/IgG1 ratio and enhanced Th1-associated cytokine secretion, alongside a potential reduction in regulatory T cell activity. These insights established critical design principles essential for the development of next-generation manganese-derived adjuvant systems, thereby advancing the frontiers of vaccinology and immunology.