Latency


Some wise soul once said that "The difference between love and herpes is that herpes is forever." He was referring to the fact that Herpes viruses are unique for their ability to persist in the host for life. During primary infection, herpes viruses replicate at the portal site and then infect the sensory nerve endings. The virus then moves up the dorsal root ganglia and remains in the ganglia until reactivation.

It would make sense if the viral replication continued to occur in the ganglia. However, experimental evidence does not bear this out. In fact, there is little evidence that virions are produced at the site of latency. The only transcript detected is LAT. This transcript accumulates in the neurons of latently infected individuals. LAT's role in reactivation is not agreed upon.

It has been shown that axonal injury causes reactivation. It is also believed, but not proven, that the severity of the primary infection correlates with the frequency and severity of reactivation events. The more severe the primary infection, the more frequent and more severe the reactivation events are thought to be. Other factors that seem to reactivate latent virus are stress, menstruation, UV light exposure and hormonal imbalance.