Researchers at Harvard University have uncovered a potential link between the Epstein-Barr virus, which is carried by some 95% of adults, and multiple sclerosis, according to a major study.
For years, EBV has been thought to be a possible cause for MS, a chronic disease affecting the central nervous system. But the peer-reviewed study published in the journal Science on Thursday may be the first to provide “compelling evidence” to illustrate this causality, Alberto Ascherio, an epidemiologist who is one of the study’s authors, said in a statement.
The study said contracting EBV could increase by 32 times the risk of developing MS, and while the findings were praised by experts, they also noted that the results did not provide a definitive link. (There are roughly 258 million adults in the United States and some 1 million MS patients nationwide.) Factors such as genetic predisposition and obesity could also be linked to MS, researchers have hypothesized.
Nonetheless, the research suggests that many MS cases could be prevented by stopping EBV infection, Ascherio said, adding that targeting the virus could also lead to a cure for MS.
The chance of MS developing in individuals who do not have EBV is “virtually [nil],” Ascherio said in an email.
Most people are infected by EBV as children. While its symptoms are mostly mild, the virus lies dormant within the human body for life. By contrast, symptoms for MS can range from numbness to pain and debilitating impairment in motor function. There is no cure, though not everyone requires therapy, and there are treatments such as steroids that can manage symptoms.
The Harvard researchers were given access to 20 years of medical data from over 10 million active-duty members of the U.S. military. From this racially diverse pool of subjects, the researchers focused on blood samples collected from 801 individuals — all of whom developed MS during their time in the military and 800 of whom tested positive for EBV.
The data provides a rare, clear look at MS developing in association with EBV — a view that is normally challenging to attain because of the relatively small number of MS patients, said Anne Bruestle, an immunologist at Australian National University (ANU) who was not involved with the research.
As part of the study, the researchers examined 123 people who had neither MS nor EBV when their blood samples were first taken. They divided them into two groups. The first, a group of 33 MS patients, contained 32 EBV-positive cases. The second, a control group of 90 people who did not have MS, only contained 51 EBV cases.
The risk of getting multiple sclerosis increased by 32-fold following an EBV infection, the researchers’ analysis found.
Bruestle noted that all the people with EBV in the two groups were infected as adults. EBV can behave differently in children — adolescents and young adults may develop infectious mononucleosis — so the conclusions of the Harvard study might not be applicable to those infected when very young, she said.
These results could still be the “tipping point” that leads to pharmaceutical companies investing in EPV vaccines, said David Tscharke, an immunologist at ANU. He noted that EBV’s relatively mild symptoms meant there had been little interest in preventing it, and there is no vaccine for the virus. (Earlier this year, Moderna said it had started initial trials for a vaccine.)