Because it was less able to replicate, the West Nile/dengue 4 virus with the RNA deletion will be the first one used in the planned clinical trials in humans. Scientists favor this virus as a vaccine because it triggered high levels of West Nile antibodies and did not produce measurable levels of virus in monkeys. It could provide life-long immunity against West Nile virus and would be highly unlikely to mutate into a disease-causing virus. It is also not likely to be passed via mosquitoes to birds or other animals.
Contact: Linda Joy
NIH/National Institute of Allergy and Infectious Diseases