Effects of vaccination on lesion development in pseudorabies virus-challenged swine

The effects of vaccination against pseudorabies virus (PRV) infection were studied in 93 barrows. Commercial attenuated and inactivated PRV vaccines were used. The protection provided was evaluated by the comparison of clinical signs, gross lesions, and microscopic lesions among vaccinated and nonvaccinated pigs after challenge exposure with a sublethal dose of PRV. Histopathologic changes are described for the CNS and other tissues. Neither the modified live- nor the inactivated-PRV vaccines prevented clinical signs or microscopic lesions in pigs after challenge exposure. However, both vaccines diminished the severity of clinical signs and microscopic lesions in the animals for a period of up to 8 months after they were vaccinated. Protection against clinical signs and microscopic lesions was absent in the pigs 10 months after the vaccination.