Vaccine Against West Nile Virus Shows Promise

By replacing parts of a distantly related virus with proteins from the West Nile virus, researchers have created a vaccine that protects monkeys against West Nile virus. Their work was reported in the September 2003 issue of Virology.

To create the vaccine, the researchers took the dengue 4 virus and replaced its outer shell proteins with corresponding proteins from West Nile virus. To ensure the safety of the chimeric virus in humans, they further weakened the West Nile/dengue 4 virus by deleting some of the genetic material, RNA in this case, from the dengue virus. After this deletion, the chimeric virus was less able to replicate itself when injected into monkeys. Even though the ability of the virus to replicate was weakened, the monkeys' immune systems were still able to produce protective antibodies against the West Nile virus proteins.

Two versions of the vaccine were tested, one with the entire dengue virus RNA and one with some of the RNA deleted. One or the other of the two vaccines was given to 12 monkeys whose antibodies to West Nile and dengue 4 were measured. Eight other monkeys were injected with either West Nile virus or dengue 4 virus for comparison. After six weeks, all 20 monkeys were injected with West Nile virus. The 12 monkeys that received a version of the West Nile/dengue 4 virus developed high levels of neutralizing antibodies that successfully fought the West Nile virus.

"Because our researchers have more than a decade of experience working with this class of virus, they could respond very quickly to the urgent public health need for a promising West Nile virus vaccine,” explained Anthony S. Fauci, M.D., director of the US National Institute of Allergy and Infectious Diseases, whose scientists developed the vaccine. Human clinical trials are expected to begin before the end of 2003.




Related Links:
National Institute of Allergy and Infectious Diseases