Proteolysis-targeting influenza vaccine strains induce broad-spectrum immunity and in vivo protection

Abstract

Generating effective live vaccines from intact viruses remains challenging owing to considerations of safety and immunogenicity. Approaches that can be applied in a systematic manner are needed. Here we created a library of live attenuated influenza vaccines by using diverse cellular E3 ubiquitin ligases to generate proteolysis-targeting (PROTAR) influenza A viruses. PROTAR viruses were engineered to be attenuated by the ubiquitin–proteasome system, which mediates viral protein degradation in conventional host cells, but allows efficient replication in engineered cell lines for large-scale manufacturing. Depending on the degron–E3 ligase pairs, viruses showed varying degrees of attenuation. In animal models, PROTAR viruses were highly attenuated and elicited robust, broad, strain-dependent humoral, mucosal and cellular immunity. In addition, they provided cross-reactive protection against homologous and heterologous viral challenges. This study provides a systematic approach for developing safe and effective vaccines, with potential applications in designing live attenuated vaccines against other pathogens. Diverse cellular E3 ubiquitin ligase–degron pairs are used to generate live attenuated influenza vaccines. Attenuation and humoral, mucosal and cellular immune responses were characterized in mouse and ferret models.