long time ago it was suspected that the common Epstein-Barr virus (EBV) can trigger multiple sclerosis.
A new study by scientists at Harvard University in the United States provides the strongest evidence to date that it does indeed play a key role in triggering this disease.
Research conducted with more than 10 million US military recruits showed that virtually all cases of multiple sclerosis are preceded by infection with the virus.
“Our group and others have investigated for years the hypothesis that EBV causes multiple sclerosis, but this is the first study to provide convincing evidence of causalityItalian researcher Alberto Ascherio, a professor of epidemiology and nutrition at the Harvard TH Chan School of Public Health and lead author of the study, said in a statement.
“This is a big step because it suggests that most cases of multiple sclerosis could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for multiple sclerosis.”
The study, following a 2-decade investigation, was published online January 13 in the journal Science.
What are EBV and multiple sclerosis?
Multiple sclerosis, which affects 2.8 million people in the world, is a chronic inflammatory disease of the central nervous system in which the immune system attacks the myelin sheaths that protect neurons in the brain and spinal cord. When this nerve covering is damaged, nerve impulses slow down or stop.
This disease can cause a wide range of potential symptoms, including problems with vision, arm or leg movement, sensation, or balance.
It is a lifelong condition that can cause serious disability, although it can sometimes be mild.
Its cause is unknown, but one of the main suspects is EBV, a type of herpes virus that infects approximately 95% of adults.
The Epstein-Barr virus transmitted mainly through saliva, for example by kissing or drinking from the same glass.
This virus is the cause of mononucleosis, also known as glandular fever or “kissing disease,” and establishes a lifelong latent infection in the host.
What did the study consist of
The difficulty in establishing a causal relationship between the Epstein-Barr virus and multiple sclerosis is that this virus infects approximately 95% of the population.
Multiple sclerosis, on the other hand, is relatively rare and the onset of symptoms begins about 10 years after infection with the Epstein-Barr virus, the TH Chan School of Public Health said in a statement.
Studies of large numbers of individuals are needed to establish whether people who have not been infected with the virus are less likely to develop multiple sclerosis.
To determine the connection between the virus and multiple sclerosis, researchers analyzed serum samples taken every two years from recruits.
In this way they determined the Epstein-Bar virus status of the recruits at the time of the first sample and the relationship between virus infection and the onset of multiple sclerosis during the period of active duty.
Serum levels of neurofilament light chain, a biomarker of nerve degeneration typical of multiple sclerosis, only increased after EBV infection.
These results “cannot be explained by any known risk factor for multiple sclerosis and suggest that EBV is the main cause” of that disease, according to the researchers.
The risk of multiple sclerosis increased 32-fold after EBV infection, but did not change after infection by other viruses.
Ascherio noted that the delay between EBV infection and the onset of multiple sclerosis may be due in part to disease symptoms not being detected during the early stages and in part to the evolving relationship between EBV and the immune system. of the host, which is repeatedly stimulated each time the latent virus reactivates.
What does the finding mean?
“There is currently no way to effectively prevent or treat EBV infection, but an EBV vaccine or specific antiviral drugs that target the virus could ultimately prevent or cure multiple sclerosis,” Ascherio said.
Researchers William Robinson and Lawrence Steinman of Stanford University wrote a commentary article accompanying the study.
Robinson and Steinman note that “these findings provide compelling data implicating the Epstein-Barr virus as the trigger for the development of multiple sclerosis“.
There is currently no vaccine against the Epstein-Barr virus, but several companies, including Moderna, are working on such a vaccine.
For Clare Walton, Principal Investigator of the Multiple Sclerosis Society in the United Kingdom, MS Society, study does not conclusively prove a chance relationship.
“There is now substantial evidence suggesting a link between Epstein-Barr virus and multiple sclerosis, especially when symptomatic infection (ie, glandular fever or infectious mononucleosis) is seen,” Walton said in a statement.
“As this new study shows, evidence is also emerging to suggest that the link may be causal. However, one or more additional factors must be required to trigger multiple sclerosis since although 9 out of 10 people worldwide are infected with EBV, most do not develop multiple sclerosis.”
The researcher pointed out that, in her opinion, “ultimately, we will not be able to be sure that EBV is causing multiple sclerosis until we can see what impact the prevention of EBV infection has on the incidence of multiple sclerosis”.
“And while research on EBV vaccines is ongoing, it’s still at an early stage. It’s great to see that research on this crucial topic is gaining momentum.”
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