Immunogen: Synthesized 23-amino acid peptide, SLLTEVETPTRNGWECKCSDSSD, the ectodomain of matrix protein 2 (M2e) of the influenza A virus (A/northern shoverl/Mississippi/11OS145/2011/H7N9) (GenBank accession# AGE08100). Specificity: Reacts with the matrix protein 2 of influenza A that contains the same ectodomain sequence.