Fighting West Nile

CAMBRIDGE, Mass.—Since West Nile virus (WNV) first appeared in the United States in 1999, more than 19,000 human cases have been reported. To help fight the spread, scientists at Acambis, Johnson County Clin-Trials, and University of Massachusetts Medical School worked to develop and test a live, attenuated vaccine against WNV that has shown positive preclinical and early-phase clinical results. They reported their work in PNAS (2006, 103, 6694-6699).

The ChimeraVax-WN02 is a chimeric vaccine based on an infectious yellow fever (YF) 17D virus, which has been used safely for more than 70 years. In this case, the YF 17D vector carries premembrane and envelope protein genes from WNV. The researchers injected the vaccine subcutaneously in monkeys and found that produced a strong serum response with few side effects.

Then, under an IND application, they tested the vaccine in a randomized double-blind placebo-controlled study in humans. Again, the researchers noted a strong and sustained serum response with few adverse events. Given these results, they believe that further clinical studies to test vaccine safety and immunogenicity are warranted.