The mechanisms for latency and reactivation of alpha herpesviridae

Alpha herpesviridae (herpes simplex virus, HSV and varicella zoster virus, VZV) is a neurotropic phathogen of humans that establishes latent infection in the sensory ganglia, and periodically reactivates from latently infected neurons. Most of basic research for analyzing the mechanism of latency and reactivation of herpes viruses has been carried out in HSV. According to the results from the molecular analysis in the neurons latently infected with HSV, during latency, the virus genome is quiescent, except for the transcription of the latency associated transcripts (LATs). Thus, it has been considered that LATs play an important role for latency and reactivation of the virus. It has been shown that LATs are required for efficient reactivation from latency in vivo, and regulate the site specificity for reactivation of the virus. Recent studies demonstrated that the quantities of latent virus are correlated with the frequency of reactivation of the virus. Moreover, it was suggested that the latency-related gene of bovine herpesvirus 1 could inhibit the apoptosis of the several cells including neuronal cells.