Expression of the influenza M2 protein in three different eukaryotic cell lines

Current influenza virus vaccines provide protection in part by antibodies induced to the two surface glycoproteins, the hemagglutinin and the neuraminidase. As a result of the continuous antigenic drift of these glycoproteins, a frequent update of the composition of influenza vaccines is required. The search for more conserved viral epitopes which would induce protective immunity against seasonal influenza viruses and eventually also to novel pandemic influenza viruses has a long history. The ectodomain of the Influenza A Virus M2 Protein has been identified as a possible candidate immunization against influenza. The present study describes the expression of cloned M2 gene in MDCK, HeLa, and COS-7 cells, i.e., in three established eukaryotic cell lines. The expression efficiency was demonstrated by immunofluorescent staining of transfected cells by ELISA, by SDS-PAGE-, and by Western blot-analysis. High level of expression was observed in COS-7 cells. Expression in HeLa and MDCK cells was less efficient. The plasmids constructed in this study may, after modifications, be used for the production of a DNA vaccine. Alternatively the expression product could be refined and used as a purified antigen for the vaccine. Thus, the M2 recombinant protein provides an ideal product for further antigenic, biochemical, structural and functional characterization of the protein and for evaluating its potential for immunodiagnosis and in vaccine studies.