A study conducted by personnel at the University of Kentucky and other institutions was aimed at determining an appropriate time for vaccinating foals for West Nile virus (WNV), reported David Horohov, PhD, at the 2008 American Association of Equine Practitioners Convention, which was held Dec. 6-10 in San Diego, Calif.

Among basic questions to be answered was whether maternal antibodies (that were passed to the foal via the mare’s colostrum) would interfere with stimulation of the foal’s immune response in the wake of vaccination, or whether vaccination with a WNV chimeric vaccine would stimulate a positive response. (The WNV chimeric vaccine was created by replacing the structural genes of the attenuated human yellow fever vaccine with the structural genes of WNV.) Involved in the study were 40 foals ranging in age from 3 to 5 months.