Harvard researchers have uncovered a clue that could be a milestone in the fight against multiple sclerosis (MS). It turns out that this incurable disease may be caused by infection with Epstein-Barr virus (EBV) - one of the most common viruses in humans. Professor Alberto Ascherio, who is leading the research, said that in the future antiviral drugs and vaccines against EBV could stop or even cure MS.
The results of the Harvard study were published on Science on 13 January 2022. Alberto Ascherio, professor of epidemiology and nutrition at Harvard Chan School and senior author of the study, said that "the hypothesis that EBV is responsible for MS has been studied by ours and other groups for several years. However, this is the first study that brings convincing evidence for causality". He added that "this is a big step that suggests that most cases of MS can be prevented by stopping EBV infection, and that taking EBV as a target could lead to the discovery of a cure for MS".
Epstein-Barr virus and multiple sclerosis. What are they?
Epstein-Barr virus, human herpesvirus 4, EBV or HHV-4 - these are the names of the virus, which is one of the most widespread in the world. Most of us pass the infection completely asymptomatic, although it stays with us for the rest of our lives and can reactivate periodically. It was discovered in 1964 by Yvonne Barr and Michael Epstein, after whom the pathogen is named.
The EBV virus can cause infectious mononucleosis, which used to be called kissing disease. It occurs when we first come into contact with the virus during adolescence (or later).
Multiple sclerosis (Latin: sclerosis multiplex - hence the acronym MS), on the other hand, is a severe, chronic and inflammatory disease of the central nervous system, during which multifocal damage to nerve tissue occurs. It most often runs in phases with periods of exacerbation and remission. Its peak incidence is between 20 and 40 years of age and occurs slightly more often in women than men. Multiple sclerosis was first described in 1868 by Jean-Martin Charcot.
Multiple sclerosis can have many symptoms, as well as syndromes of symptoms. Among the most common are disorders:
- movement,
- sensory,
- views,
- autonomous,
- cognitive,
- mood.
Pain syndromes and chronic fatigue are also common symptoms. Multiple sclerosis is one of the most common causes of disability among young people and can have several forms, such as progressive-relapsing. Currently, there is no drug that can stop the progression of the disease and cure it completely. Some of the measures make it possible to regain lost functions and slow down the further progression of the disease.
How the link between EBV and MS was discovered
Establishing that there is a causal relationship between EBV and MS has been difficult. This is because EBV infects most people (around 95 per cent), yet multiple sclerosis is a relatively rare disease. Its symptoms appear about 10 years after EBV infection. To investigate the link between one and the other, the researchers conducted a study on more than 10 million young people who had served on active duty in the US military. They identified 955 patients who were diagnosed with multiple sclerosis during their period of service.
The researchers analysed serum samples collected every two years by the military and then whether and what the association was between the presence of EBV and the incidence of MS. The results showed that the risk of developing multiple sclerosis increased up to 32-fold after infection with Epstein-Barr virus, and did not change after infection with other viruses. On top of this, serum levels of neurofilament light chain, which is a typical biomarker for MS, only increased after EBV infection. The researchers noted that "the findings cannot be explained by any known risk factor for MS and suggest that EBV is a major cause of MS".
Why the delay between EBV infection and the onset of multiple sclerosis? Professor Ascherio indicates that it may be due to two reasons. Firstly, the undetectability of the symptoms of the disease in its early stages. And secondly, from the partially evolutionary link between the EBV virus and the host's immune system, which is stimulated every time the dormant 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 may eventually prevent or cure MS," - Ascherio said.
Source: cowzdrowiu.pl