Immunology, Med Lifestyle, Medical News, Neurodevelopmental disorders, Neuroscience

Epstein-Barr virus suggested as leading cause of multiple sclerosis

After a longitudinal analysis found that those who had been previously infected with the Epstein-Barr virus (EBV) had a 32-fold increased risk of developing multiple sclerosis (MS), researchers are now looking at EBV as a possible target for finding a cure for MS.

According to a study headed a research group from Harvard T.H. Chan School of Public Health, infection with the Epstein-Barr virus (EBV) is likely the cause of multiple sclerosis (MS), a degenerative disease that affects 2.8 million people worldwide and for which there is no cure.

Alberto Ascherio, professor of epidemiology and nutrition at Harvard Chan School and senior author of the study shared his thoughts, stating, “The hypothesis that EBV causes MS has been investigated by our group and others for several years, but this is the first study providing compelling evidence of causality. This is a big step because it suggests that most MS cases could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for MS.”

MS is a central nervous system inflammatory condition that destroys the myelin sheaths that protect neurons in the brain and spinal cord. Its genesis is unknown, although EBV, a herpes virus that may cause infectious mononucleosis and leaves a latent, lifelong infection in the host, is one of the leading hypotheses. Because EBV infects nearly 95% of individuals, MS is a very rare condition, and MS symptoms appear about 10 years after EBV infection, establishing a causal association between the virus and the disease has proven challenging.

The researchers performed a survey among more than 10 million young individuals on active duty in the United States military to see whether there was a link between EBV and MS. They found 955 people who were diagnosed with MS during their time in the military.

The researchers examined blood samples collected twice a year by the military to assess the soldiers’ EBV status at the time of the first sample and the link between EBV infection and MS development during active service. Following infection with EBV, the risk of MS increased 32-fold in this population, whereas it remained constant after infection with other viruses. Only after EBV infection did serum levels of neurofilament light chain, a hallmark of MS-related nerve damage, rise. The findings, which cannot be explained by any recognized MS risk factor, point to EBV as the primary driver of MS.

According to Ascherio, the delay between EBV infection and the development of MS might be related to the disease’s early symptoms going unnoticed, as well as the growing link between EBV and the host’s immune system, which is constantly activated whenever the latent virus reactivates.

Ascherio suggested the applications of the groups findings, saying, “Currently there is no way to effectively prevent or treat EBV infection, but an EBV vaccine or targeting the virus with EBV-specific antiviral drugs could ultimately prevent or cure MS.”

The study was published in Science, on January 13th, 2022.

Abstract. Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system of unknown etiology. 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.

Bjornevik K, Cortese M, Healy BC, Kuhle J, Mina MJ, Leng Y, Elledge SJ, Niebuhr DW, Scher AI, Munger KL, Ascherio A. Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis. Science. 2022 Jan 21. doi: 10.1126/science.abj8222. Epub ahead of print. PMID: 35025605.

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