We already assumed it, we are now almost certain. According to a new study by American researchers, published on January 13 in the journal Science, multiple sclerosis is most likely caused by a very common virus, the Epstein-Barr virus (EBV), responsible for mononucleosis.
Multiple sclerosis (MS) is an autoimmune disease caused by the breakdown of myelin, the membrane that forms a sheath around nerve fibers, which slows down the transmission of information sent by the brain to the rest of the body. It affects 2.8 million people worldwide.
“The link between multiple sclerosis and the Epstein-Barr virus has been suspected for several decades because studies had already shown it in a cohort at one time, decrypts Céline Louapre, neurologist at the Pitié-Salpêtrière hospital in Paris. But the great novelty of this study, which makes it very significant, is its methodology, which makes it possible to follow a very large number of people for a very long time. »
“Out of nearly 1,000 people who have MS, all have contracted EBV”
Researchers at Harvard University have indeed followed for twenty years 10 million young adults engaged in the American army, of which 955 have been diagnosed with multiple sclerosis, and have “tested the hypothesis that MS is caused by the Epstein-Barr virus”, summarize the American researchers in the synopsis of the study. However, according to their results, “the risk of MS increased 32-fold after infection with EBV but did not increase after infection with other viruses, including similarly transmitted cytomegalovirus”.
Even more convincing, “out of nearly 1,000 people who have MS, all have contracted EBV (1), which means that the Epstein-Barr virus is a necessary factor in the appearance of multiple sclerosis”, explains Professor Jean Pelletier, neurologist at the Timone Hospital in Marseille and President of the Scientific Council of the Foundation for Aid to Research on Multiple Sclerosis.
Necessary but not unique factor
” In contrast, says Jean Pelletier, not everyone who has contracted EBV will develop multiple sclerosis. » And so much the better, because this virus, which causes mononucleosis, is contracted by 90 to 95% of the general adult population, most often asymptomatically. If Epstein-Baar is therefore necessary, it is therefore not enough to trigger multiple sclerosis, which undoubtedly depends, in order to develop, on other triggering factors, genetic or environmental. The lack of sunshine, and therefore of vitamin D, is for example tested in other work in progress.
In short, said Alberto Ascherio, lead author and professor of epidemiology at Harvard’s School of Public Health, it’s about “the first study providing convincing evidence of causation”. Above all, he added, “This is an important step, as it suggests that most cases of multiple sclerosis could be prevented by stopping Epstein-Barr virus infection”. In other words : “Targeting this virus could lead to the discovery of a cure. »
While treatments already make it possible to slow down the development of the disease, now “If we develop a vaccine that eliminates Epstein-Barr, we can think that multiple sclerosis will decrease and perhaps even be eliminated”, considers Jean Pelletier, who thinks that“a five-year horizon is a reasonable time frame for a vaccine”. The American company Moderna announced last week that it had started clinical trials on humans of a vaccine against the Epstein-Barr virus.