Study results suggest that infection with Epstein-Barr virus may be the leading cause of multiple sclerosis.
Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system, for which there is currently no definitive cure. Affecting 2.8 million people worldwide, MS attacks the myelin sheaths that work to protect neurons in the brain and the spinal cord. Although the cause of MS is still unknown, infection with Epstein-Barr virus (EBV) has been found to be a top suspect requiring further investigation into its association with MS, according to a study from researchers at the Harvard TH Chan School of Public Health.
“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,” said study senior author Alberto Ascherio, MD, DrPH, professor of epidemiology and nutrition at Harvard TH Chan School of Public Health, in a press release. “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.”
EBV is a herpes virus that can cause infectious mononucleosis and can exist in its host as a latent infection for the rest of their lives. However, pinpointing the causal relationship between EBV and MS has posed problems due to inconclusive results from prior analysis of population data. Currently, 95% of adults have been infected by EBV, yet MS is relatively rare and does not directly correlate to this level of infection of the general population. Furthermore, the onset of MS has been found to begin approximately 10 years following EBV infection.
During the study, the investigators included 10 million young adults on active duty in the US military in their analysis. With the medical data available for these individuals in the US military’s database, the investigators were able to identify 955 servicemembers who had been diagnosed with MS while in military service.
Based on analyses of serum samples conducted biennially by the US military, the investigators were able to determine the EBV status of soldiers based on the results of their samples. The data were then analyzed to assess the correlation between EBV status and MS onset during the period in which they were on active duty. Among the study cohort, the investigators observed that risk of MS increased 32-fold after infection with EBV, yet this risk level remained unchanged in relation to infection with other viruses.
Furthermore, the investigators observed that serum levels of neurofilament light chain, which is a biomarker of MS associated with nerve degeneration, was found to increase only after servicemembers were found to be infected with EBV. These results are not correlated with any known risk factor for MS, suggesting EBV is the leading cause of MS, according to the study authors.
Additionally, the observed delay between EBV infection and MS disease onset may also be due to the symptoms of MS going undetected during its earliest stages, Ascherio explained in the press release. However, this delay may also be due to the evolving and progressive relationship between EBV and the immune system of its host. Upon reactivation of the latent virus within the host, EBV is repeatedly stimulated, which may correlate with the onset of MS or its symptoms.
“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,” Ascherio said in the press release.
Epstein-Barr virus may be leading cause of multiple sclerosis. Boston, MA: Harvard TH Chan School of Public Health