Influenza viruses are vulnerable to frequent changes in their haemagglutinin (HA) and neuraminidase (NA) surface proteins (especially type A viruses), resulting in new virus strains unfamiliar to the immune system. Antibodies in the blood and other cells of the immune system, which are responsible for protection against repeated infection with the virus, are less effective if the virus surface protein changes; the greater the change, the less effective is the body’s immune defense following natural immunization (via infection) or vaccination.
BiondVax’s approach uses a combination of conserved epitopes derived from the influenza virus as immunogens, forming the vaccine. The “conserved epitopes” are common to most human flu virus strains regardless of their antigenic drift and shifts. These conserved epitopes are used to activate the human immune system in a long-lasting and effective manner against known and future strains of the influenza virus. These conserved epitopes are restricted to the viral structure and are not shared by any human protein, thus they are unlikely to induce an autoimmune phenomenon.
- Immunogenicity: the selected peptides are immunogenic thus induce specific immune responses after exposure to the vaccine. A peptide that is immunogenic is also known as an epitope. These responses are reactivated following natural infection.
- Conserved epitopes: the epitopes are “conserved” i.e., they are not vulnerable to antigenic changes and remain unchanged despite changes that occur in other peptides forming part of the virus’ protein. This quality enables the vaccine to induce an immune response to a wide variety of virus strains, thus the term “a universal multi-season/multi-strain vaccine”.
- Combination of epitopes: The specific selection of conserved epitopes induce production of antibodies (by B-cells = humoral arm) and a variety of T-cells (= cellular arm). The activation of both arms of the immune system is responsible for the enhanced effect of this vaccine.