A vaccine already approved in the United States to prevent a related disease protects experimental animals and may also protect people from the most serious complication associated with West Nile virus infection, say researchers from the University of Texas Medical Branch at Galveston (UTMB).
They report their findings today at the 50th Annual Meeting of the American Society of Tropical Medicine and Hygiene in Atlanta.
Dr. Robert Tesh, a professor in the Center for Tropical Diseases at UTMB and his colleagues tested two vaccines for Japanese encephalitis (JE) for their its ability to protect hamsters from the fatal encephalitis (inflammation of the brain) that is associated with West Nile viral infection.
The JE virus is a flavivirus, a member of the same viral family as the West Nile virus, dengue virus and St. Louis encephalitis virus.
"It looks like the West Nile virus is spreading throughout the Western Hemisphere and it will probably go all the way through the tropics and down to Argentina says Tesh.
In the United States we haven't had much exposure to flaviviruses; but we wanted to see what could happen when the West Nile virus reached an area like Central America where people have already had exposure to other flaviviruses, either through infection or vaccination.
Previous studies in India have suggested that prior infection with the JE virus will protect monkeys from fatal West Nile infections. In this study Tesh and his colleagues first inoculated hamsters with one of three flavivirus vaccines: a live-attenuated JE vaccine currently used on millions of people in China, a killed-virus JE vaccine currently approved for use in the United States and a yellow fever vaccine.
"If we infect hamsters with the New York strain of West Nile virus about half will die of encephalitis if they have not had a previous flavivirus infection," says Tesh. But in the case of the JE-vaccinated hamsters "none of them
Contact: Jim Sliwa
American Society for Microbiology