More effective flu vaccines might be on the horizon, U.S. researchers say.
As reported online this week in the journal Proceedings of the National Academy of Sciences, a team at the La Jolla Institute for Allergy and Immunology (LIAI) has compiled the most comprehensive analysis to date of published influenza (flu) A virus epitopes -- the critical sites on the virus that are recognized by the immune system.
While researchers have already deciphered the molecular structures of essentially all flu virus strains, less is understood about how the immune system recognizes these pathogens.
The study looked at data from the Immune Epitope Database and Analysis Research Program, a repository of immune epitopes for disease-causing microbes, including strains of the flu virus.
"The purpose of the database is to provide a catalog of molecules and structures that scientists around the world can quickly assess and use to understand the immune response to a variety of epitopes, or methodically predict responses to as yet untested targets," lead investigator Alessandro Sette, head of the Vaccine Discovery division at LIAI, said in a prepared statement.
Sette and colleagues examined 600 different epitopes from 58 strains of influenza A virus. They looked at how similar epitopes are between different strains of bird and human flu viruses. This is important, since flu viruses can rapidly mutate into new strains of the virus. If epitopes are similar among strains, the immunity a person has developed toward one strain may provide protection against another.
The research team found hundreds of epitopes that were similar among different strains of the flu virus, and one, in particular, that appears ideal for multi-strain vaccines.
More research may help scientists identify targets for vaccines that could offer broader protection against strains of the flu. But researchers must first fill in gaps in the database about flu viruses.
For instance, most of the flu virus data was obtained from analyses of immune responses of mice and other animals; very little comes from humans or birds.
"The bottom line is that this study shows us where we need to go," said project director Stephen Wilson, chief technology officer at LIAI, in a prepared statement. "Hundreds of flu epitopes have already been published and are now in the database, but critical gaps become apparent when one looks for human antibody targets."
The National Institute of Allergy and Infectious Diseases has more about the flu.