A study of more than ten million people suggests that previous infection with the Epstein-Barr virus (EBV), which causes mononucleosis, would be necessary so that multiple sclerosis could later develop. Prevention and cure, then, could be much closer.
Multiple sclerosis (MS) is a progressive disease that affects 2.8 million people worldwide and for which there is no definitive cure.
Ten million military
The hypothesis that EBV causes MS has been investigated for several years, but this is the first study to provide convincing evidence of causality. This is a big step because it suggests that most cases of MS could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for MS.
MS is a chronic inflammatory disease of the central nervous system that attacks the myelin sheaths that protect neurons in the brain and spinal cord. Its cause is unknown, but one of the main suspects is EBV, a herpes virus that can cause infectious mononucleosis and establishes a lifelong latent infection in the host.
Establishing a causal relationship between the virus and the disease has been difficult because EBV infects approximately 95% of adults, MS is a relatively rare disease, and the onset of MS symptoms begins about ten years after EBV infection. .
To determine the connection between EBV and MS, researchers conducted a study among more than 10 million young adults on active duty in the United States military, and identified 955 who were diagnosed with MS during their tour of duty.
The team analyzed 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. In this cohort, MS risk increased 32-fold after EBV infection, but did not change after infection by other viruses. Serum levels of neurofilament light chain, a biomarker of nerve degeneration typical of MS, increased only after EBV infection. The findings cannot be explained by any known risk factors for MS and suggest that EBV is the main cause of MS.