Research suggests that most cases of multiple sclerosis could be prevented by stopping a well-known virus infection
Posted on January 14, 2022
Multiple sclerosis (MS), a degenerative disease, could have an infectious origin. The Epstein-Barr virus (EBV), known as the human herpesvirus or as the cause of mononucleosis or 'kissing disease', is, according to a study published this Thursday in 'Science', the cause of multiple sclerosis, a progressive disease for which there is no definitive cure and which affects 2.8 million people worldwide.
A team of researchers from the Chan School of Public Health at Harvard University (USA) could have finally found the trigger for this disease, something that has been investigated for many years. "For years our group and others have investigated the hypothesis that EBV causes MS, but this is the first study to provide convincing evidence of causation", highlights Alberto Ascherio, lead author of the study.
According to Ascherio, "This is a big step because it suggests that most cases of MS could be prevented by stopping EBV infection". Furthermore, he stresses that by focusing on this virus "we could finally identify a cure for MS".
MS is a chronic autoimmune disease that works by damaging the myelin in the body of those affected, a fatty material that insulates the nerves and allows them to transmit electrical impulses to and from the brain quickly. The body's own tissue is treated as a foreign body, and the onset of the disease is often triggered by a combination of genetic and environmental factors. MS is the most common chronic neurological disease in young adults between 20 and 40 years of age in Europe and North America, especially in women.
Although its cause is unknown, one of the main suspects has always been EBV, a herpes virus that can cause infectious mononucleosis and generates a latent infection for life in the host.
Until now, it has been difficult to establish a causal relationship between the virus and the disease because EBV infects approximately 95% of adults and the onset of MS symptoms begins about 10 years after EBV infection.
To determine the connection between EBV and MS, researchers conducted a study of more than 10 million young adults in the U.S. Army and identified 955 who were diagnosed with MS during their active duty.
The researchers analysed serum samples taken every two years by the military and determined the EBV status of the soldiers at the time of the first sample and the relationship between EBV infection and the occurrence of MS during the period of active duty.
Thus they saw that in this group the risk of MS increased 32 times after EBV infection, but was not altered after infection with other viruses.
The analysis showed that serum levels of neurofilament light chain, a biomarker of nerve degeneration typical of MS, increased only after EBV infection.
The findings, they write, cannot be explained by any other known risk factors for MS and suggest that EBV is the leading cause of multiple sclerosis.
Ascherio suspects that the delay between EBV infection and the onset of MS may be due, on the one hand, to the fact that the symptoms of the disease were not detected during the early stages and, on the other, to the relationship in evolution between EBV and the host's immune system, which is repeatedly stimulated each time the latent virus reactivates.
They point out that, due to these elements implicated in the pathogenesis of MS, "EBV infection is likely to be" necessary, but not sufficient, to trigger the development of MS".
EBV infection, they claim, is the initial pathogenetic step in MS, but other factors must be activated for full pathophysiology.
Antivirals that target EBV may provide effective therapy, they wonder, especially when given early.
Although there is no way to effectively prevent or treat EBV infection today an EBV vaccine or targeting the virus with EBV-specific antiviral drugs could, we think, prevent or cure MS.
And they conclude: "Now that the initial trigger of MS has been identified, perhaps it could be eradicated".
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