Characterization of latent infections in mice inoculated with herpes simplex virus which is clinically resistant to acyclovir.

Mice were inoculated into the ear pinna with herpes simplex virus (HSV) using a strain which is resistant to acyclovir (ACV) chemotherapy. The original inoculum was resistant to ACV because it contained a proportion of thymidine kinase-defective (TK-) virions. This had been obtained previously by passage of an HSV type 1 strain in mice undergoing suboptimal therapy. The cervical dorsal root ganglia were subsequently explanted from the infected mice and the presence of latent virus therein revealed by reactivation in vitro. These explant cultures yielded both TK+ and TK- viruses on reactivation. The establishment of latent infections was not affected by chemotherapy during the acute infection. One TK- ganglion isolate when studied in detail was found to be attenuated and thus resembled previously examined TK- strains which had been selected in vitro for ACV-resistance.