Immunogenicity and protective efficacy of recombinant M2e.Hsp70c (Hsp70(359-610)) fusion protein against influenza virus infection in mice.

New strategies in vaccine development are urgently needed to combat emerging influenza viruses and to reduce the risk of pandemic disease surfacing. Being conserved, the M2e protein, is a potential candidate for universal vaccine development against influenza A viruses. Mycobacterium tuberculosis Hsp70 (mHsp70) is known to cultivate the function of immunogenic antigenpresenting cells, stimulate a strong cytotoxic T lymphocyte (CTL) response, and stop the induction of tolerance. Thus, in this study, a recombinant protein from the extracellular domain of influenza A virus matrix protein 2 (M2e), was fused to the C-terminus of Mycobacterium tuberculosis Hsp70 (Hsp70c), to generate a vaccine candidate. Humoral immune responses, IFN-γ-producing lymphocyte, and strong CTL activity were all induced to confirm the immunogenicity of M2e.Hsp70c (Hsp70(359-610)). And challenge tests showed protection against H1N1 and H9N2 strains in vaccinated groups. Finally these results demonstrates M2e.Hsp70c fusion protein can be a candidate for a universal influenza A vaccine.