Single immunization of non-adjuvanted recombinant TTFC-mi3 nanoparticle vaccine elicited a rapid and potent protective immunity against tetanus.

The conventional inactivated tetanus toxin plays an instrumental role in preventing tetanus. Nevertheless, the challenges associated with its production process, the potential for adverse reactions, and reduced effectiveness in vulnerable populations such as neonates and the elderly rise the need for a novel tetanus toxin vaccine. Recombinant subunit vaccine offer a viable solution, and the tetanus toxin fragment C (TTFC) is emerging as a promising candidate. In this study, through spontaneous isopeptide bond formation we conjugated the recombinant TTFC to self-assembled mi3 nanoparticle, which derived from an optimized KDPG aldolase, and generated the TTFC-mi3 protein nanoparticle vaccine. We found that TTFC-mi3 is stable, uniform spherical nanoparticles. Comparing with the free TTFC alone, TTFC-mi3 enhances the uptake and subsequent activation of dendric cells (DCs). In addition, a single dose of adjuvant-free TTFC-mi3 elicited a more rapid and potent protective immunity in mice. Moreover, TTFC-mi3 is of favorable safety in vitro and in vivo. Our findings indicate that TTFC-mi3 is a rapid-response, non-aluminum-adjuvanted vaccine against tetanus.