DNA vaccination against respiratory syncytial virus in young calves.

A DNA vaccine encoding the fusion (F) gene (DNA-F) of bovine respiratory syncytial virus (BRSV) induced significant protection against BRSV infection in young calves. However, serum antibody to RSV developed more slowly in animals vaccinated with DNA-F when compared with those previously infected with BRSV. Furthermore, protection against BRSV infection was not as great as that induced by prior BRSV infection. Although there was little difference in the level of protection induced in calves vaccinated with DNA-F by either the intramuscular (i.m.) or intradermal (i.d.) routes, only the i.m. route primed for a rapid BRSV-specific IgA response after BRSV challenge. These results indicate that a DNA vaccination may be effective against RSV infection even in very young infants and calves.