Influenza virus inhibiting peptides

A pharmaceutical composition for the treatment or prevention of an influenza infection comprising:

• an isolated polypeptide including a sequence of at least 8 contiguous amino acid residues of the fusion initiation region (FIR) of an influenza A hemagglutinin 2 protein or a peptide analog of the sequence;
• wherein the hemagglutinin 2 protein includes an amino-terminal alpha-helix and a carboxy-terminal alpha-helix;
• and the FIR is a segment of the full length hemagglutinin 2 protein which is bounded by an amino-terminal region within the amino-terminal alpha-helix and a carboxy terminus within the carboxy-terminal alpha-helix, with a cysteine loop therebetween;
• and wherein:
• the amino-terminal region of the FIR comprises a portion of the final 10 to 20 amino acid residues of the amino-terminal alpha-helix of the hemagglutinin 2 protein, and includes 3 or 4 hydrophobic amino acid residues, a positively-charged amino acid residue, a negatively-charged amino acid residue, and an aromatic amino acid residue;
• and
• the carboxy terminus of the FIR is the carboxy terminus of the first peptide sequence of the hemagglutinin 2 protein beyond the amino terminal helix, which exhibits a positive Wimley-White interfacial hydrophobicity.