A measles vaccine, modified to express a West Nile virus protein, protects mice against West Nile virus, according to French researchers.

The researchers believe the vaccine could potentially give humans full protection from West Nile as early as eight to 10 days after inoculation.

Dr. Frederic Tangy, from Institut Pasteur in Paris, and his colleagues tested the effectiveness of the widely used measles vaccine, engineered to produce a protein normally found on the surface the West Nile virus. The antigen causes the body to produce infection-fighting antibodies that produce immunity to the disease.

Mice that were given the modified vaccine did not die or become ill when they were injected with a lethal dose of West Nile virus, the team found, whereas mice that didn’t get the vaccine died within three to four days after being given the virus.

“Mice were still fully protected at six months after vaccination (corresponding to a quarter of mouse life),” Tangy noted. The researchers reported their findings in the January 15 edition of The Journal of Infectious Diseases.

Studies of the vaccine in primates are ongoing, Tangy said, with results expected later this year.

In people, the vaccine is expected to remain effective for at least 10 years after it is administered, Tangy said.

The vaccine could be used in the general population or to control local outbreaks of West Nile virus.

SOURCE: Journal of Infectious Diseases, January 15, 2005.