Epstein-Barr virus may be the main cause of multiple sclerosis

BOSTON, Mass. — Affecting close to three million people all over the world, multiple sclerosis (MS) is an awful autoimmune disease that causes the immune system to attack the brain and spinal cord. There is currently no cure, but researchers from Harvard may have found the likely trigger. Their study finds the main cause of MS may be contracting an infection of the Epstein-Barr virus (EBV).

“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,” says senior study author Alberto Ascherio, professor of epidemiology and nutrition at the Harvard Chan School, in a university release. “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.”

Considered a chronic inflammatory disease of the central nervous system, MS targets the myelin sheaths protecting neurons in the brain and spinal cord. While its primary cause has been unclear, scientists have suspected EBV plays a role.

Epstein-Barr virus is a form of herpes?

The Epstein-Barr virus is actually a variant of herpes, and just like the type that gives people cold sores, this virus never truly leaves the body. EBV causes infectious mononucleosis and establishes a latent, lifelong infection within hosts. Complicating matters is the fact that almost everyone carries EBV. That’s right, estimates show that 95 percent of adults have EBV.

Multiple sclerosis, meanwhile, is much rarer. Among people with both, the study finds MS usually develops about a decade after EBV infection.

In pursuit of some clearer answers, study authors analyzed over 10 million young adults currently serving on active duty in the U.S. military. That process led to the identification of 955 adults diagnosed with MS while serving.

The team analyzed blood samples collected every two years, allowing the researchers to ascertain each soldier’s EBV status at the time of the first sample, as well as the relationship between EBV infection and subsequent MS development while still on active duty. Results show the risk of MS increased 32-fold following EBV infection. Risk levels didn’t change at all upon infection with different viruses.

Moreover, serum levels of neurofilament light chain — a biomarker of the nerve degeneration among MS patients — only increased following EBV infection. All in all, study authors say other MS risk factors can’t explain away the apparent link between EBV and multiple sclerosis.

Why the long delay between EBV and MS development?

You may be wondering why it takes so long after contracting EBV for MS to appear. Prof. Ascherio theorizes MS symptoms may simply go unnoticed during the disease’s earlier stages. It’s also possible that EBV changes how the immune system interacts with other viruses.

“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,” Prof. Ascherio concludes.

The study is published in the journal Science.