Australian Scientists Propose West Nile Vaccine

August 11, 2003

WASHINGTON (Reuters) - A vaccine using a harmless relative of the West Nile virus could offer a way to protect people against the disease, researchers in Australia said on Monday.

Mice vaccinated with the harmless virus, known as Kunjin, were protected against the sometimes deadly West Nile virus, they reported in the Proceedings of the National Academy of Sciences.

West Nile, seem commonly in Africa and parts of Europe, was imported into the United States in 1999. Carried by birds and mosquitoes it has quickly spread to most of the country and parts of Canada.

This year it has sickened 182 people and killed five in the United States, according to the U.S. Centers for Disease Control and Prevention.

Most people do not show any symptoms of the disease but it can cause encephalitis, an inflammation of the brain that can turn deadly.

There is a vaccine for horses, which can die from West Nile, but no vaccine for people. Several companies and the U.S. government are working on a new vaccine.

West Nile and Kunjin -- seen in southeast Asia and Australia -- are very similar genetically, but Kunjin produces only rare, nonfatal cases of disease.

Roy Hall of the University of Queensland in Brisbane, Australia and colleagues injected mice with Kunjin DNA and found the mice produced antibodies against the virus.

When injected with what should have been lethal doses of West Nile, the mice did not even become ill, they reported.

This approach was used in the first-ever vaccine invented -- the smallpox vaccine. Edward Jenner inoculated patients with a relatively harmless cousin of smallpox called cowpox, and protected them from smallpox.

The current smallpox vaccine uses vaccinia virus, another related virus.

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