Researchers at the Wistar Institute have developed a vaccine that might one day prevent you from having to roll up your sleeves for another annual flu shot. Administered through the nose, it has the potential to protect recipients against current and future strains of the influenza virus. So far it has only been tested in mice.
Current flu vaccines work by triggering an immune response to two large viral-coat proteins. “You are protected against incoming infection, but the problem is that these proteins mutate very frequently in the virus, so the shot you get today is not good for next year,” says Dr. Laszlo Otvos, an associate professor in Wistar’s immunology program who contributed his expertise as a peptide chemist to the project. (Dr. Walter Gerhard, professor of immunology, was senior author of the report in the June issue of the journal Vaccine.)
In contrast to traditional flu vaccines, the Wistar prototype contains a synthetic peptide that mimics a third, smaller protein on the virus, called M2, that remains largely constant. Mice given the vaccine generated a strong antibody response to M2—“actually the antibody titer was higher [in them] than in the mice who were recovering from the virus itself.” Because it is “a synthetic construct, we can make large quantities and high quality,” Otvos adds.
Another advantage of the engineered vaccine is that it contains no viral particles. (In contrast, a recently approved nasal spray called FluMist—designed to provide annual protection against the flu—is “a virus product” and cannot be given to patients over 49 because of the rare chance of infection.)
Though FDA approval could be sought for the Wistar vaccine in as little as two years, a number of tests —and questions—remain, Otvos says. For the next step “we really need to see what happens with the virus when there is evolutionary pressure to mutate the protein. The good thing here is that this is a short protein, so we can almost anticipate and can make a construct that could cover all possible permutations.” —S.F.
