Rationally engineered cationic ferritin nanoparticles overcome pre-existing immunity to adenoviral vectors.

Viral vectors and protein nanoparticles represent important platforms in vaccine delivery, yet their potential synergy to overcome fundamental biological barriers remains largely unexplored. To address the challenge of pre-existing immunity against viral vectors, we rationally engineered a cationic human ferritin nanoparticle, termed (+)hF, designed to electrostatically assembles with adenovirus serotype 5 (Ad5) into a supramolecular complex. This construct was generated via structure-guided point mutations that introduced positive surface charges while retaining the innate self-assembly capability of the ferritin nanocage. The resulting (+)hF formed nanocomplexes with Ad5, which enhanced transgene expressions both in vitro and in vivo and effectively reduced sensitively to anti-Ad5 neutralization. In murine models with pre-existing immunity, intranasal immunization with (+)hF-complexed Ad5-based vaccines (encoding antigens for SARS-CoV-2 or Hendra virus) elicited significantly higher antigen-specific IgG and neutralizing antibody titers. A key advantage of (+)hF is its endogenous origin, which ensures high biocompatibility by preventing the induction of anti-carrier antibodies and any associated immune burden. This study presents a new paradigm that engineers programmable biointerfaces to synergize viral vectors with protein nanocages, offering a general strategy to circumvent critical biological barriers for enhanced vaccine and gene delivery.