CD4 and influenza: M-001 is a single recombinant protein that consists of three repetitions of nine conserved linear epitopes from HA (four B and one CD4 T cell epitopes), NP (two CD8 T cell and one CD4 T cell epitopes), and M1 (one peptide containing both B and CD8 T cell epitopes), which were derived from influenza A and B strains expressed in Escherichia coli (E. coli).