Herpes simplex virus type 1 ICP-0 induces reactivation of pseudorabies virus from latently infected trigeminal ganglia explant cultures.

Pseudorabies virus (PrV), like other alphaherpesviruses, is a neurotropic virus that can establish a latent infection in swine. Reactivation of PrV from latency may occur spontaneously or after induction with corticosteroids. The mechanisms involved in the establishment of latency and reactivation are currently unknown. Here, we examined gene-specific reactivation of PrV by herpes simplex virus type 1 (HSV-1) immediate early protein, ICP-0. Primary neuronal cell cultures established from the trigeminal ganglia of latently infected swine were superinfected with recombinant adenoviruses expressing ICP-0. Reactivation of PrV occurred in cultures that were superinfected with two different ICP-0-expressing adenovirus recombinants, but not in cultures that were either mock-infected, or superinfected with wild-type adenovirus, or recombinant adenoviruses not expressing ICP-0. Infectious PrV was detected between 4 and 7 days postinfection, regardless of the promoter driving expression of ICP-0. Results from these experiments show that HSV-1 ICP-0, a homologue of PrV EP0, can induce PrV reactivation from explanted trigeminal ganglia of latently infected swine.