An mRNA vaccine candidate encoding cholera toxin subunit B and conserved antigens of influenza viruses confers cross-protection against influenza a viruses in adult and aged mice.

Currently, vaccination with influenza vaccines is still an effective strategy to prevent infection by seasonal influenza virus. However, seasonal influenza vaccines frequently fail to induce effective immune protection against rapidly changing seasonal influenza viruses and emerging zoonotic influenza viruses. In addition, seasonal influenza vaccines may not confer potent protection in elderly and immunocompromised individuals. There is an urgent need to develop potent broad-spectrum influenza vaccines to address this problem. Herein, we designed an mRNA-based broad-spectrum influenza vaccine candidate encoding cholera toxin subunit B and conserved antigens of influenza viruses. In both adult and aged mice, this universal influenza mRNA vaccine candidate stimulated robust T-cell and humoral immune responses and conferred effective protection against broad-spectrum influenza viruses in both adult and aged mice.