Scientists believe they may have found out a 'leading cause’ of multiple sclerosis (MS), a life-long autoimmune condition that can affect the brain and spinal cord, and can lead to serious disability.
Researchers have long suspected a link between MS and Epstein-Barr Virus (EBV), but have struggled to demonstrate a strong connection.
In a bid to establish the link between the two, a team at Harvard University examined samples from more than 10 million people and recently published their findings in the journal Science.
The team analysed samples collected from army, navy and air force service members since 1993 - the research goldmine being the result of the US military taking blood samples from its soldiers every two years.
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Alberto Ascherio, an epidemiologist at Harvard T.H. Chan Medical School, said the researchers found that EBV infection increased the risk of MS 32-fold.
In their abstract, the authors explain: “We tested the hypothesis that MS is caused by Epstein-Barr virus (EBV) in a cohort comprising more than 10 million young adults on active duty in the US military, 955 of whom were diagnosed with MS during their period of service.
"Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus. Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion.
"These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS."
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Speaking to the BBC, Ascherio explained: "Individuals who were not infected with the Epstein-Barr virus virtually never get multiple sclerosis.
"It's only after Epstein-Barr virus infection that the risk of multiple sclerosis jumps up by over 30-fold."
Ascherio said the study offers the ‘first’ compelling evidence that EBV is indeed causing MS, adding that it was ‘quite common’ for viruses to infect a lot of people, but only cause severe complications for a few.
Professor Gavin Giovannoni, from Queen Mary University of London, also told the outlet: "It is very, very strong evidence that this virus is likely to be the cause of multiple sclerosis."
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According to the BBC, there are ‘several’ companies already working on an EBV vaccine - including Moderna, which is using the same technology it did to speedily develop its Covid vaccine.
In the study, the authors said: "The extremely low MS risk in EBV-negative individuals suggests that by far most MS cases are caused by EBV and could thus potentially be prevented by a suitable vaccine.
"The addition of MS to the list of diseases that an EBV vaccine could target strengthens the rationale to accelerate ongoing research with the primary goal of preventing infectious mononucleosis and posttransplantation lymphoproliferative disease."
Jess Hardiman