Evidence was presented at a medical conference that suggested that a reactivated ancient retrovirus embedded in the human genome may be active in chronic fatigue syndrome (CFS) and multiple sclerosis (MS) patients. Danish scientists at the same conference suggested that the activation of this retrovirus, dormant in healthy individuals, could be the reason why autoimmune conditions worsen with viral infections.

"Patients with profoundly fatiguing diseases such as MS and CFS may be particularly susceptible to HERV-K18 activation," said Dr. Brigette Huber by Brigitte Huber, PhD, of the Tufts University School.  Using an SNP-based genotyping method, Dr. Huber found that both MS and CFS patients (whose illness had been triggered by infectious mononucleosis) were at a higher relative risk for containing HERV-K18 variants known to induce superantigen activity. Superantigens are proteins that are able to induce a strong undifferentiated T-cell response believed to deplete the immune system over time.

Viral activity and/or immune activation has been shown to trigger HERV-K18 activity. Both Epstein-Barr virus infection (infectious mononucleosis) and interferon-alpha administration are associated with HERV-K18 activity. "HHV-6 activates HERV-K18 as well," said Danish investigator Per Hollsberg, MD and professor from the University of Aarhus In Denmark. His PhD student Vanda Lauridsen Turcanova presented this data at the same conference. "Furthermore, this retrovirus activation may have important consequences for autoimmunity," he added.

HERV-K18 activation may be the endpoint of an HHV6/EBV interferon pathway operating in both MS and CFS. HHV-6 is being investigated as a co-factor in both diseases. Other retroviruses, HERV-H and HERV-W, have been implicated in MS by other researchers. Over 75% of MS patients meet the criteria for CFS. Fatigue is often the most disabling symptom for MS patients. The two diseases also share characteristics such as grey matter atrophy, impaired cerebral glucose metabolism, autonomic nervous system activity and altered patterns of brain activity.

Dr. Huber's study suggests that endogenous retroviral activation in CFS and MS could produce some of the symptoms associated with both diseases. She has received a National Institutes of Health (NIH) grant to study these issues. Per Hollsberg has done extensive research on the role of EBV and HHV-6 in multiple sclerosis.

For more information, visit http://www.hhv-6foundation.org/