Vaccination against "unfamiliar" flu viruses could protect against other strains

Vaccination against "unfamiliar" flu viruses could help protect against other strains of the flu, according to new research compiled by Emory University's Vaccine Center, University of Chicago and Mt. Sinai School of Medicine.

The research showed humans immunized against the H5N1 avian flu virus developed cross-reactive antibodies against a protein in the virus, while volunteers who received a standard seasonal flu vaccine developed antibodies against a different region of the viral protein.

Scientists recently identified a region of the protein-hemagglutinin-called the stem that does not mutate as much as other regions. The area could be the key to creating a vaccine that is effective against various strains of the flu.

Ali Ellebedy, a postdoctoral fellow at Emory Vaccine Center, said the key to making the body produce antibodies against the viral protein stem was that none of the volunteers had been exposed to the virus before.

"Our previous research led us to hypothesize that immune responses to the stem region are likely to be stronger after exposure to hemagglutinin molecules derived from flu viruses which the human population has been minimally exposed to," Ellebedy said.

Researchers previously discovered that patients infected with the 2009 H1N1 flu virus developed broad cross-reactive antibodies, and most of them had never before been exposed to the virus. After the virus began circulating in the general population and was included as part of standard flu immunizations, however, studies of immune responses showed antibodies were generated against the head region of the protein and not the stem.

"Our findings delineate a potential vaccination strategy where H5N1 or H7N9 immunization could be used not only for immunologically priming the population to quickly respond to serious pandemic influenza threats, but also for generating broadly neutralizing antibodies against influenza in humans," the authors of the study said.