Gancyclovir

Gancyclovir (brand name Cytovene) is an antiviral drug with activity against cytomegalovirus.

A 2014 study in mice suggested gancyclovir reduced microglial activation; however follow-up mice studies and in vitro research found it did not have this effect.

The authors of the 2014 paper later published a follow-up paper (2017) based on in vitro and in vivo experiments using ganciclovir. This time they found a potentially pro-inflammatory response, specifically that ganciclovir, in sufficient doses, might stimulate a type-I interferon response in microglia. The authors attributed this response to a DNA-sensing protein called STING. While this result might appear to contradict their earlier anti-neuroinflammatory finding, they suggest it could indicate ganciclovir (GCV) "can exhibit dual function in microglia [...]: in naïve state, GCV induces microglia to be 'primed'; on the other hand, GCV reduces inflammation in active microglia."