The Epstein-Barr virus (EBV) may be the leading cause or trigger of multiple sclerosis (MS), a study led by Harvard researchers suggests.
“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.”
Authors say establishing a causal relationship between EBV and MS has been hard because EBV infects about 95 percent of adults while MS is relatively rare, and the onset of MS symptoms takes place about 10 years after initial EBV infection.
Researchers analyzed blood samples taken every two years (during routine HIV testing) by the military.
The researchers analyzed up to three blood samples for each soldier with MS, and assessed the soldiers’ EBV status at the time of the first sample (taken when most in the military were under 20 years old), and the relationship between EBV infection and MS onset throughout their period of active duty.
“Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus,” authors wrote.
Authors also found that serum levels of neurofilament light chain (NfL)—a biomarker of nerve degeneration that’s typical in MS—increased only after EBV infection.
“These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS,” authors said in their report, titled “Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis.”
The Hidden Cause of MS?
Virologist Jeffrey I. Cohen, who heads the Laboratory of Infectious Diseases at the National Institute of Allergy and Infectious Diseases (NIAID), who was not involved in the research, told The Scientific American that he is cautious about claiming causation, and it still must be shown that preventing EBV prevents MS. However, he acknowledges the results are significant.Ascherio said that a possible reason why the onset of MS is much delayed from the initial EBV infection could be because symptoms are not notable or are undetected in the early stages of MS, and could also be due to how EBV interacts with the infected person’s immune system, which is stimulated whenever the latent EBV virus reactivates.
“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 suggested.
MS involves the immune system attacking the protective sheath, or myelin, that covers nerve fibers, disrupting communications between the brain and the rest of the body. Symptoms range from mild to severe, and include numbness or weakness in the limbs affected, slurred speech, fatigue, vision issues, and problems with bowel and bladder function.