By Lauran Neergaard
Associated Press
New evidence strengthens the hypothesis that one of the world's most common viruses may cause some people to develop multiple sclerosis (MS), a potentially disabling disease that occurs when cells of the immune system mistakenly attack the protective layer nerve fibers, gradually eroding them.
The Epstein-Barr virus has long been suspected of playing a role in the development of multiple sclerosis.
This is a difficult connection to prove because almost everyone is infected with Epstein-Barr, usually as a child or young adult, but only a small proportion develop MS.
But researchers from Harvard University published this Thursday one of the largest studies to date to support this theory.
Blood samples from military personnel were used in the study.Getty Images/iStockphoto
The researchers analyzed
blood samples from more than 10 million people in the Army
and found that the risk of MS increased 32-fold after becoming infected with Epstein-Barr.
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The Army regularly performs blood tests on its soldiers, so researchers were able to access samples stored from 1993 to 2013, looking for antibodies that signaled viral infection.
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Only 5.3% of military personnel did not show any signs of Epstein-Barr when they joined the Army.
The researchers compared 801 subsequently diagnosed MS cases over the 20-year period with 1,566 service members who never developed the disease.
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Only one of the multiple sclerosis patients had no evidence of Epstein-Barr virus before diagnosis.
And, despite intensive searching, the researchers found no evidence that other viral infections played a role in this diagnosis.
The results "strongly suggest" that Epstein-Barr infection is "a cause and not a consequence of MS
," report lead study author Alberto Ascherio, of the Harvard TH Chan School of Public Health, and colleagues. in the journal
Science
.
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It's clearly not the only factor, considering that nearly 90% of adults have antibodies that show they've had Epstein-Barr, while nearly a million people in the US have MS, according to the National Society. of Multiple Sclerosis.
The virus appears to be "the initial trigger," William H. Robinson and Lawrence Steinman of Stanford University wrote in an editorial accompanying Thursday's study.
But they warned that "other fuses must be lit," such as genes that can make people more vulnerable.
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The Epstein-Barr virus is best known for causing "mononucleosis," or infectious mononucleosis, in adolescents and young adults, but it often has no symptoms.
It is a virus that remains inactive in the body after the initial infection and has also been linked to the subsequent development of some rare autoimmune diseases and cancers.
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It is not clear why.
One possibility is what is called "molecular mimicry," meaning that viral proteins may resemble some nervous system proteins so much that they induce the wrong immune attack.
Regardless, the new study is "the strongest evidence to date that Epstein-Barr plays a role in causing MS," said Mark Allegretta, vice president for research at the National Multiple Sclerosis Society.
And that, he added, "opens the door to potentially preventing MS by preventing Epstein-Barr infection."
There are attempts to develop vaccines against Epstein-Barr, including a small study just started by Moderna Pharmaceuticals, best known for its COVID-19 vaccine.