First Vaccine for West Nile Virus Announced

By Ellen Kuwana Neuroscience for Kids Staff Writer November 15, 2001 Researchers at Yale University reported in the November 1, 2001 issue of the Journal of Immunology that they had successfully tested a vaccine for the West Nile virus in mice. West Nile virus can cause death in birds and encephalitis in humans. Since the first case of West Nile virus among humans in the United States was diagnosed in 1999, there have been 10 deaths, most among the elderly. Although most of the cases have been in New York City, there have been some reports of West Nile virus in other parts of the country. West Nile virus usually infects birds. From a virus isolated from an infected bird, the Yale scientists selected a protein on the virus' surface, called an envelope protein. The gene for the protein was then engineered into the genetic material of special strain of the E. coli bacteria. The bateria acts like a protein factory pumping out many copies of the protein as the E. Coli multiplies. This protein was injected into mice to stimulate their immune systems to produce antibodies. The researchers then tested the immunized mice to see if they had gained immunity to the West Nile virus. Tests showed that mice were immune to the virus, and scientists hope that this vaccine will also be effective in humans. Researchers also think that this protein may help them to develop tests to diagnose West Nile virus more easily.