A temporal analysis of acyclovir inhibition of induced herpes simplex virus type 1 In vivo reactivation in the mouse trigeminal ganglia.

It is generally assumed that reactivation of latent herpes simplex virus occurs through initiation of lytic viral gene transcription from the latent viral genome. Thus, antiviral compounds such as acyclovir, whose activation is dependent upon viral thymidine kinase, should be effective in preventing the initial production of infectious virus associated with reactivation. To test this concept, the ability of acyclovir to prevent the production of infectious virus was determined in the murine hyperthermic stress (HS) model of in vivo reactivation. Acyclovir treatment after HS blocked the production of infectious virus within the ganglia. Efficacy was dependent upon the timing of the first post-HS dose and the length of exposure to acyclovir. A single dose administered 6-9 h after HS resulted in >90% reduction in reactivation. Acyclovir administered 12 h after HS resulted in 75% reduction, but there was no effect if treatment was delayed for 18 h after HS.