WASHINGTON — Multiple sclerosis, a neurodegenerative disease that has no cure and affects some 2.8 million people worldwide, is largely caused by infection with the Epstein-Barr virus, according to a new article by researchers at Harvard University.
Their findings, published this week in the journal Science, appear to confirm a long-standing but hard-to-prove hypothesis, and were welcomed by outside experts who said attention should now turn to preventions and cures.
“This is the first study to provide compelling evidence of causation,” said Alberto Ascherio, professor of epidemiology and nutrition at Harvard TH Chan School of Public Health and lead author of the study, in a statement.
“This is a big step forward as it suggests that most cases of MS could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure. against MS.
EBV is a herpes virus that can cause infectious mononucleosis – sometimes called kissing disease – and stays in the host for life.
MS is a chronic inflammatory disease that destroys the myelin sheaths protecting neurons in the brain and spinal cord, causing problems with vision, balance and mobility.
The idea of a link between the two had been explored for years, but was difficult to establish definitively, in part because EBV is extremely common, affecting around 95% of adults, and the symptoms of MS begin to develop a decade after infection.
To investigate the question, researchers looked at more than 10 million young adults on active duty in the US military over a 20-year period and identified 955 who were diagnosed with MS during their time in service.
They analyzed blood serum samples taken every two years, determining the soldiers’ EBV status at the time of the first sample and the relationship between EBV infection and the onset of MS.
They found that the risk of MS increased 32-fold after infection with EBV, but there was no such increase for infection with other viruses.
Levels of a protein called neurofilament light chain, a well-known MS biomarker, only increased after MS – and the authors were able to show that their findings could not be explained by other factors. risk.
Writing in a related commentary in the same journal, William Robinson and Lawrence Steinman of Stanford University said that since everyone is infected with EBV but very few people develop MS, genetic factors are ” additional fuses” for MS after the initial trip.
They also noted some hypotheses about how EBV causes MS. These include that some of the virus’ proteins could “mimic” the myelin sheath, causing the immune system to attack.
Another idea is that EBV could turn certain immune cells, called B cells, against the host.
Ascherio, the author of the new study, concluded: “Currently, there is no way to effectively prevent or treat EBV infection, but an EBV vaccine or targeting the virus with antiviral drugs specific to EBV could ultimately prevent or cure MS.”
Moderna began a clinical trial of an EBV mRNA vaccine this month, a development that takes on added importance given the new discovery.