Detection of HSV-1 genome in central nervous system of latently infected mice

Herpes simplex virus type 1 (HSV-1) can establish latent infections in peripheral nerve ganglia and the central nervous system (CNS) of experimentally infected mice. Latent infections of peripheral nervous tissue are characterized by the ability to recover infectious virus from explant cultures of most of the latently infected ganglia. In contrast, infectious virus is infrequently recovered from the CNS of latently infected mice following explant culture, although viral DNA can be detected in CNS tissue. The presence of incomplete or defective viral genomes during the latent CNS infections has been proposed to explain this difference between the two latent infections. To characterize the completeness and the physical state of the latent viral genome, we used Southern blot hybridization to analyse the viral DNA from latently infected mouse ganglia and brains. Our results, reported here, indicate that most, if not all, of the HSV-1 genome is present in latently infected CNS tissue and that the latent viral genome exists in a form other than linear, unit length DNA.