Investigation: Several pieces of evidence link a multiple sclerosis virus

There is more evidence that one of the world’s most common viruses can put some people on the path to developing multiple sclerosis.

Multiple sclerosis is a potentially disabling disease that occurs when the cells of the immune system mistakenly attack the protective coating on the nerve fibers and gradually erode them.

The Epstein-Barr virus has long been suspected of playing a role in the development of MS. It’s a link that’s hard to prove because almost everyone gets infected with Epstein-Barr, usually as children or young adults – but only a small proportion develop MS.

On Thursday, Harvard researchers reported on one of the largest studies yet to support the Epstein-Barr theory.

They tracked blood samples kept from more than 10 million people in the U.S. military and found that the risk of MS increased 32-fold after Epstein-Barr infection.

The military regularly conducts blood tests for its members, and researchers checked samples stored from 1993 to 2013 in search of antibodies that signaled viral infection.

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Only 5.3% of recruits showed no sign of Epstein-Barr when they joined the military. The researchers compared 801 MS cases subsequently diagnosed over the 20-year period with 1,566 service members who never got MS.

Only one of the MS patients had no evidence of Epstein-Barr virus before diagnosis. And despite intensive research, the researchers found no evidence that other viral infections played a role.

The results “strongly suggest” that Epstein-Barr infection is “a cause and not a consequence of MS,” reported study author Dr. Alberto Ascherio of the Harvard TH Chan School of Public Health and colleagues at the journal Science.

This is clearly not the only factor given that about 90% of adults have antibodies that show they have had Epstein-Barr – while nearly 1 million people in the United States live with MS, according to the National Multiple Sclerosis Society.

The virus appears to be “the first trigger,” Drs. William H. Robinson and Lawrence Steinman of Stanford University wrote in an editorial that followed Thursday’s study. But they warned, “additional fuses must be ignited,” such as nuisances that could make people more vulnerable.

Epstein-Barr is best known for causing “mono” or infectious mononucleosis in teens and young adults, but often occurs without symptoms. A virus that remains inactive in the body after the initial infection has also been linked to later development of some autoimmune diseases and rare cancers.

It is not clear why. Among the possibilities is what is called “molecular mimicry”, which means that viral proteins can resemble some nervous system proteins so much that it provokes the faulty immune attack.

Either way, the new study is “the strongest evidence to date that Epstein-Barr is contributing to the cause of MS,” said Mark Allegretta, vice president of research at the National Multiple Sclerosis Society.

And that, he added, “opens the door to potentially prevent MS by preventing Epstein-Barr infection.”

There are attempts to develop Epstein-Barr vaccines, including a small study just launched by Moderna Inc., best known for its COVID-19 vaccine.

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