I have written about antivirals in the past, and thought that it was time to do an update.
- EBV, HHV5 and other virus in CFS
- Valganciclovir, HHV-6, EBV and CFS
- Valganciclovir antiviral and CFS
- Valacyclovir, EBV and CFS
- Valacyclovir which reported some patients with complete resolution of symptoms).
- Myths of Chronic EBV and Lyme
Viral re-activation is common with ME/CFS . It’s a chicken and the egg scenario. Did the viral re-activation cause ME/CFS or did ME/CFS cause viral re-activation. Most people do not ask about the third leg of this stool: Was there something else that contributed to both viral re-activation and ME/CFS (or the contemporary “Long Haul Covid” syndrome).
My model for ME/CFS is a microbiome dysfunction. So the question becomes, can a microbiome dysfunction also account for viral re-activation? Latest research says yes and identifies some bacteria involved!
Correlation analyses between the microbiome and viral titers revealed a positive correlation with Gracilibacteria, Absconditabacteria, and Abiotrophia and a negative correlation between Oribacterium, Veillonella, and Haemophilus. There was also a significant positive correlation between microbiome richness and EBV viral titers.The influence of spaceflight on the astronaut salivary microbiome and the search for a microbiome biomarker for viral reactivation 
It appears to be a two way street: “Our study is the first to report the impact of long-term subclinical CMV infection on host immunity and gut microbiota” 
It also extends to the food that is consumed and microbiome interaction (i.e. production of short- and medium-chain fatty acids by some bacteria consuming the food).
Our studies of the differential activities of SCFAs and MCFAs as inducers or inhibitors of viral reactivation have implications for oncolytic strategies. The HDAC inhibitors butyrate, phenylbutyrate, and VPA have been investigated as lytic activators in cells, mice, and patients (31, 85,–89). One risk of applying lytic induction therapy is that incomplete inhibition of viral replication by antiviral drugs could allow secondary infection and disease progressionActivation and repression of Epstein-Barr Virus and Kaposi’s sarcoma-associated herpesvirus lytic cycles by short- and medium-chain fatty acids 
Vitamin D levels are usually low, very low with ME/CFS patients. “vitamin D deficiency can be considered as a risk factor for CMV reactivation” “For EBV, viral load was significantly higher when 25(OH)D levels were low, demonstrating an inverse correlation between 25(OH)D levels and EBV load. ” . Anna Dorothea Hoeck,MD, has had success in putting some ME/CFS patients in remission by using high dosages of Vitamin D (likely those that also has viral reactivation).
While there is not an abundance of literature, we see that the metabolites produced by the microbiome can activate or deactivate existing latent viral infections. We also know a shift in bacteria is associated with increase viral titers. Last, we know that virus can alter the microbiome.
We end up with three legs on the stool with the microbiome being significant. It is very significant because it is the easiest to change.
Virus reactivation alters the microbiome which then produces metabolites causing fatigue, etc. The altered microbiome then feeds the virus…. I have often used the expression “Viro-forming the microbiome”. It’s a feedback loop that can be hard to break.