Strengthening the Effectiveness of the Candidate Influenza Vaccine by Combining Conserved Sequences of Hemagglutinin and M2 protein

The development of universal influenza vaccine - a vaccine directed to all subtypes of human influenza A viruses - is the really actual problem task. This paper presents the comparative characteristic of the specific activity of various recombinant proteins consisting of antigenic determinants of influenza A virus - the ectodomain of the M2 protein (M2e) and a fragment of the second subunit of the hemagglutinin (the amino acid sequence 76 - 130). Flagellin - Salmonella typhimurium protein was used as carrier protein and as adjuvant. We use two forms of flagellin: full size and with deleted hypervariable region. The proteins showed high immunogenicity, and the ability to prevent lethal infection of influenza virus in mice. Full-length flagellin with HA2 (76 - 130) and M2e on the C-terminus (protein Flg-HA2-4M2e) demonstrated the most protective properties. It provides 100% survival immunized mice that were challenge with a high dose of influenza A (H3N2) - 10 LD50. Proteins containing only full sized flagellin with M2e or flagellin truncated form with M2e at the C-terminus and HA2 within the hypervariable region, protected 75% of animals from lethal infection. Protein Flg-HA2-4M2e is promising for further study as a vaccine