Valganciclovir

Valganciclovir (brand name Valcyte) is an antiviral medication mostly used to treat cytomegalovirus infections. It is active against a number of herpesviruses.

Chronic fatigue syndrome
Valganciclovir is used off-label to treat patients with ME/CFS. Studies have shown mixed evidence of efficacy. In a 2013 study by Montoya, et al, some improvement using valganciclovir was reported in a subset of ME/CFS patients with elevated IgG antibody titers against HHV-6 and EBV.

Valganciclovir may improve systems by via its broad spectrum antiviral activity against latent herpesviruses, which may reactivate in immunocompromised patients, including ME/CFS patients.

Valganciclovir became of additional interest as a potential ME/CFS treatment, particularly as an anti-inflammatory, when a 2014 study in mice suggested gancyclovir (the compound that valganciclovir converts to) reduced microglial activation; ME/CFS patients have been shown to have chronic activation of microglia. However follow-up mice studies and in vitro research found gancyclovir did not reduce microglial activation.

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."

Notable studies

 * 2012, Response to valganciclovir in chronic fatigue syndrome patients with human herpesvirus 6 and Epstein-Barr virus IgG antibody titers. (Full text)
 * 2013, Randomized Clinical Trial to Evaluate the Efficacy and Safety of Valganciclovir in a Subset of Patients With Chronic Fatigue Syndrome (Full text)

Learn more

 * 2016, Valganciclovir antiviral and CFS