Vaccine for West Nile Shows Promise

Researchers said Monday that they have developed a vaccine that combines key parts of two viruses and has been shown to protect monkeys from West Nile virus, a mosquito-borne illness that has killed 10 Americans this year.

Scientists at the National Institute of Allergy and Infectious Diseases, one of the National Institutes of Health, made the vaccine by placing West Nile virus proteins into a modified virus that causes dengue fever. This created a live but weakened virus.

When injected into monkeys, the hybrid virus protected the animals from injected doses of West Nile virus. The researchers said the combined viruses crippled the West Nile virus but still caused a strong immune response against it.

In a laboratory test, the researchers injected 12 monkeys with the combined virus vaccine and injected eight other monkeys with either the West Nile virus or the dengue virus.

Six weeks later, all 20 monkeys were injected with West Nile virus. The dozen that received the combined virus vaccine developed antibodies that successfully protected the animals from the West Nile virus.

Human clinical trials with the vaccine are to begin this year, Dr. Brian Murphy, a researcher in NIAID’s Laboratory of Infectious Diseases, said Monday.

“We’re optimistic that our engineered virus vaccine will provide long-term immunity to West Nile virus, but the human clinical trials will give us the definitive data,” Murphy said.

The researchers published details of their work in the September issue of the journal Virology.