A self-adjuvant trivalent T4 bacteriophage nanoparticle vaccine induces broad protective immunity against...

Orthoebolaviruses, including Zaire virus, Sudan virus, and Bundibugyo virus, remain major public health threats because of their high case-fatality rates and recurrent outbreaks. Although licensed vaccines provide effective protection against EBOV, broadly protective vaccines against multiple pathogenic orthoebolavirus species remain unavailable. Here, we developed T4 bacteriophage-based nanoparticle vaccines displaying glycoproteins (GPs) from EBOV, SUDV, and BDBV by leveraging the SpyTag/SpyCatcher conjugation system. Monovalent vaccine candidates and a trivalent formulation (T4-Mix) were generated to evaluate their potential for broad orthoebolavirus immunization. Intramuscular immunization of BALB/c mice elicited robust GP-specific humoral and cellular immune responses without the need for exogenous adjuvants. In homologous surrogate challenge models using replication-competent recombinant vesicular stomatitis viruses expressing EBOV, SUDV, or BDBV GP, all monovalent vaccines conferred complete protection against their respective challenge viruses. Furthermore, the optimized trivalent T4-Mix formulation provided complete protection against rVSV-EBOV, rVSV-SUDV, and rVSV-BDBV challenges. Collectively, these findings demonstrate that the T4 bacteriophage functions as both an antigen delivery vehicle and an intrinsic immunostimulatory scaffold, highlighting its potential as a versatile platform for the development of broadly protective multivalent orthoebolavirus vaccines.