CTA1-M2e-DD: a novel mucosal adjuvant targeted influenza vaccine.

At present few vaccine candidates exists against potentially pandemic influenza virus infections. We provide compelling evidence that a targeted fusion protein based on the CTA1-DD adjuvant and containing tandem repeats of the matrix protein 2 (M2e) ectodomain epitope, CTA1-3M2e-DD, confers strong protective immunity against a potentially lethal challenge infection with influenza virus in mice. The formulation was highly effective for mucosal immunizations and promoted high M2e-specific serum IgG and mucosal IgA antibody titers and an hitherto unknown anti-M2e CD4 T cell immunity. This novel CTA1-3M2e-DD fusion protein combines adjuvant and a conserved influenza A antigen in a promising candidate for a universal anti-influenza vaccine.