Latent pseudorabies virus infection in pigs.

Latent infection with the TOP strain of pseudorabies virus (PRV) was established in 6 weeks old piglets. Infectious virus was found in oropharyngeal swabs till day 10 post infection (p.i.); later on, attempts to detect the virus remained unsuccessful. However, PRV could be isolated by explantation of tonsils, cervical lymph nodes, nasal mucosa and gasserian ganglia. These tissues were removed between 160 and 181 days p.i., during cultivation, infectious PRV was released into the culture fluid from the 3rd to the 11th day of the explantation. PRV antigen was seen by immunofluorescence only in explants coming from gasserian ganglia. It was localized in both neurons and satellite cells. In piglets given hydrocortisone before explantation, the number of virus-producing explants was not enhanced as compared to that of virus-producing explants from untreated animals.