Latency of a thymidine kinase-negative pseudorabies vaccine virus detected by the polymerase chain reaction.

Latent viral DNA was detected by the polymerase chain reaction in trigeminal ganglia of all of 10 pigs that were necropsied 81 or more days after they had been infected intranasally with a thymidine kinase-negative (TK-) vaccine strain of pseudorabies virus (PRV). Failure to reactivate virus from any of the same pigs by earlier treatment with dexamethasone suggested that even though latency can be established with TK- PRV, subsequent reactivation may be a relatively rare event.