Virus Identified as Cause of Multiple Sclerosis

A new study shows the Epstein-Barr virus (EBV) is essential for the development of multiple sclerosis (MS), although not all individuals who have EBV develop MS. According to this study, the risk of MS infection increased 32-fold after EBV infection, but remained unchanged after infection with other viruses.

“The hypothesis that EBV causes MS has been investigated by our group and others for several years, but this is the first study providing compelling evidence of causality,” said Alberto Ascherio, MD, DrPH, professor of epidemiology and nutrition at Harvard Chan School and senior author of the study. “This is a big step because it suggests that most MS cases could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for MS.”

In the study, the researchers analyzed serum samples taken biennially by the military and determined the soldiers’ EBV status at time of first sample and the relationship between EBV infection and MS onset during the period of active duty. In this cohort, the risk of MS increased 32-fold after infection with EBV but was unchanged after infection with other viruses. Serum levels of neurofilament light chain, a biomarker of the nerve degeneration typical in MS, increased only after EBV infection. The findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS.

According to Dr. Ascherio, the delay between EBV infection and the onset of MS may be partially due to the disease’s symptoms being undetected during the earliest stages and partially due to the evolving relationship between EBV and the host’s immune system, which is repeatedly stimulated whenever latent virus reactivates.

The discovery raises hopes for the future development of a cure for MS, which affects nearly 2.8 million people worldwide. “Currently there is no way to effectively prevent or treat EBV infection, but an EBV vaccine or targeting the virus with EBV-specific antiviral drugs could ultimately prevent or cure MS,” said Dr. Ascherio.

Moderna recently announced it had begun clinical trials in humans for a vaccine against EBV.