Characterization of immunity induced by M2e of influenza virus

The extracellular-domain of influenza Matrix 2 protein (M2e) is considered as a putative target for designing universal influenza vaccines. However, the mechanism by which M2-based vaccine induces protection has not been clear. In this study, we analyzed the immunity induced by free synthetic M2e peptide and found the peptide was highly immunogenic. Without carrier proteins, the synthetic M2e peptide could induce M2e-specific IgG antibodies in both incomplete Freund's and aluminum adjuvant. The peptide could also provoke M2e-specific T cell response, which could not be mounted by influenza virus. Moreover, immunization with M2e peptide could protect mice from a lethal challenge with influenza virus. These results provide useful information for the development of M2e-based influenza vaccine.