Multiple sclerosis, a progressive disease for which there is no definitive cure, “is probably” caused by infection with the Epstein-Barr virus, which causes mononucleosis, according to a large twenty-year study published today by Science.
The Harvard University-led research followed more than 10 million US military recruits and identified 955 who were diagnosed with multiple sclerosis during their tour of duty. The hypothesis that the Epstein-Barr virus (EBV) causes multiple sclerosis has been analyzed by various scientific groups for several years, but “this is the first study that provides convincing evidence of causality,” according to the lead author of the research Alberto Ascherio of the Harvard TH Chan School of Public Health.
The scientist considered that this is “a big step, because it suggests that the majority” of cases of multiple sclerosis (MS) “could be prevented by stopping the infection” by the virus that causes mononucleosis, known as kissing disease, and that targeting the Epstein-Barr virus “could lead to the discovery of a cure for MS.”
Multiple sclerosis, which affects 2.8 million people worldwide, is a chronic inflammatory disease of the central nervous system that attacks the myelin sheaths that protect neurons in the brain and spinal cord. Although its cause is unknown, one of the main suspects is EBV, a herpes virus that can cause infectious mononucleosis and establishes 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, while multiple sclerosis is relatively rare and the onset of symptoms begins about ten years after infection by the Epstein-Barr virus, says the TH Chan School of Public Health in a statement. To determine the connection between the two, the researchers analyzed serum samples taken every two years from the military.
In this way, they determined the Epstein-Bar virus status of the soldiers at the time of the first sample and the relationship between infection by it and the appearance of multiple sclerosis during the period of active service.
The team found that “the risk of MS increased 32-fold after EBV infection, but did not change after infection with other viruses,” the note states. Serum levels of neurofilament light chain, a biomarker of nerve degeneration typical of multiple sclerosis, only increased after Epstei-Barr virus infection.
These results, according to the research team, “cannot be explained by any known risk factor for MS and suggest that EBV is the main cause” of this disease. Ascherio explained that the delay between EBV infection and the appearance of multiple sclerosis “may be due, in part, to the fact that the symptoms of the disease are not detected during the early stages and, in part, to the evolutionary relationship between the EBV and the host’s immune system, which is repeatedly stimulated each time the latent virus reactivates.”
There is currently no way to effectively prevent or treat Epstein-Barr virus infection, but a vaccine against it or targeting it with specific antiviral drugs “could ultimately prevent or cure multiple sclerosis,” added the expert. .