Protection against pseudorabies virus infection by intranasal vaccination of newborn pigs.

Intranasal vaccination of newborn pigs with pseudorabies virus (PRV) strain Iowa S62/26 tk- gX- Bgal+ was evaluated to determine whether protective immunity could be stimulated in pigs given colostrum from immune sows. Three litters were vaccinated (2 litters from PRV-immune sows and 1 born to a PRV-free sow), and 2 were left as nonvaccinated controls (1 passively immune and 1 PRV-nonimmune). Pigs were then challenge-exposed at 15 weeks of age with virulent PRV strain 4892. Vaccinated pigs that suckled nonimmune sows developed serum PRV-neutralizing antibody by 15 weeks of age and did not die or have reduction in weight gain or febrile response after challenge exposure. Vaccinated pigs that suckled PRV-immune sows were seronegative for PRV at the time of challenge exposure and had less weight loss and fever than did challenge-exposed control pigs. Intranasal vaccination at birth did not stimulate adequate immunity to reduce virus shedding after challenge exposure in any of the vaccinated pigs.