|Photo: LOIC VENANCE / AFP|
Multiple sclerosis (MS), a progressive disease that affects 2.8 million people worldwide and for which there is no definitive cure, is probably caused by infection with the Epstein-Barr virus (EBV), responsible for the so-called heart disease. kiss. The finding is the result of a study led by researchers at the Harvard TH Chan School of Public Health in the United States, and was published in the online edition of the journal Science.
“The hypothesis that EBV causes MS has been investigated by our group and others for several years, but this is the first study that provides convincing evidence of causality,” said Alberto Ascherio, professor of epidemiology and nutrition and senior author on the paper. . “This is a big step, because it suggests that most cases of MS can be prevented by stopping the EBV infection, and that targeting (research) at the virus could lead to the discovery of a cure.”
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 not known, but one of the main suspects is EBV, a herpes virus that can cause infectious mononucleosis, the kissing disease, and establish a latent, lifelong 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 symptoms begins about 10 years after infection with the virus. To determine the connection, the researchers conducted a study of more than 10 million young adults who were active in the US Armed Forces. Of those, 955 were diagnosed with multiple sclerosis during the service period.
The team analyzed serum samples collected every two years from the military and determined the EBV status at the time of the first sample and the relationship between infection with the virus and the onset of MS. In this cohort, the risk of multiple sclerosis increased 32-fold after infection with EBV, but remained unchanged considering infection with other viruses. Serum levels of neurofilament light chain, a biomarker of typical MS nerve degeneration, increased only after EBV infection. The findings cannot be explained by any known risk factors for MS and suggest the virus as the main cause of the disease.
Ascherio says the delay between EBV infection and the onset of MS may be partly due to the symptoms of the disease not being detected during the early stages and partly due to the evolution of the relationship between EBV and the host’s immune system, which is repeatedly stimulated whenever the latent virus is reactivated. “There is currently no way to effectively prevent or treat EBV infection, but a vaccine against the virus or antiviral drugs specific to it could prevent or cure multiple sclerosis,” Ascherio said.