There is new evidence that one of the world’s most common viruses may set some people on a path to developing multiple sclerosis (MS).
This potentially disabling disease occurs when cells of the immune system mistakenly attack the protective coating on nerve fibers, gradually destroying them.
Epstein-Barr virus, a widespread human herpes virus, has long been suspected to play a role in the development of MS. It’s a connection that’s difficult to prove because nearly everyone becomes infected with Epstein-Barr, usually as children or young adults—but only a small fraction develop MS.
On Thursday, Harvard University researchers reported one of the largest studies yet to support the Epstein-Barr theory.
They tracked archived blood samples from more than 10 million people in the US military and found that the risk of MS increased 32 times following an Epstein-Barr infection.
The military routinely conducts blood tests to its members and researchers examined samples stored from 1993 to 2013, hunting for antibodies indicating viral infection.
Only 5.3 percent of recruits showed no signs of Epstein-Barr when they enlisted in the military. Researchers later compared 801 MS cases diagnosed over a 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 prior to diagnosis. And despite a thorough search, researchers found no evidence that other viral infections played a role.
The findings “strongly suggest” that Epstein-Barr infection “is a cause and not a consequence of MS,” study author Dr. Alberto Escherio from the Harvard T.H. Chan School of Public Health and colleagues report in the journal Science.
Virus best known for causing ‘mono’
That’s clearly not the only factor, given that about 90 percent of adults have antibodies that show they have Epstein-Barr — while there are about a million people in the U.S. living with MS, according to the National Multiple Sclerosis Society. according.
Canada, meanwhile, has one of the highest rates of MS in the world. Statistics from the MS Society of Canada show that an estimated 90,000 Canadians are living with the disease, or one out of every 400 people.
The virus appears to be the “early trigger,” Dr. Stanford University’s William H. Robinson and Lawrence Steinman wrote in an editorial accompanying Thursday’s study. But he cautioned, “additional fuses must be ignited,” such as genes that can make people more vulnerable.
Epstein-Barr is best known for causing “mono” or infectious mononucleosis in adolescents and young adults, but often causing no symptoms. A virus that remains dormant in the body after initial infection, it has also been later linked to the development of certain autoimmune diseases and rare cancers.
It is not clear why. One of the possibilities is what’s called a “molecular mimic,” meaning that the viral protein may look so similar to certain nervous system proteins that it induces a false immune attack.
The new Harvard research was not a randomized trial that could prove cause and effect, but the link suggested by the findings makes it “the strongest evidence to date that Epstein-Barr contributes to what causes MS,” says Mark Allegretta. Said, vice president of research at the National Multiple Sclerosis Society.
And he said, “Epstein-Barr opens the door to potentially preventing MS by preventing infection.”
Efforts are underway to develop Epstein-Barr vaccines, including a small study initiated by Moderna, the company now best known for its COVID-19 vaccine.