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Researchers identify the virus that causes multiple sclerosis

The link between the disease and the Epstein-Barr virus was already known, but it is now well enough documented to point the way to potential treatments.

A group of researchers from the prestigious Harvard School of Public Health in the United States has managed to precisely identify the virus that causes multiple sclerosis, a terrible neurodegenerative disease that is now incurable. Hopefully, this crucial step will make it possible to tackle the development of a real cure.

Professor Bjornevik’s team managed to precisely confirm the identity of the culprit: it is HHV-4, better known as the Epstein-Barr virus (VEB). It is a virus already well known for its role in several pathologies; it is known to cause certain relatively mild illnesses such as mononucleosis. But it is also the cause of life-threatening emergencies like Burkitt’s lymphoma – the most aggressive form of cancer ever documented in humans.

For several years, research also suspected the existence of a link between EBV and multiple sclerosis. For example, several studies have already established that having declared mononucleosis constitutes a risk factor. The link exists, it is a fact; but it still needed statistically demonstrate the correlation, and it is now done.

A very large study

To achieve this, the researchers were able to rely on a huge database including millions of American soldiers. For any statistician or public health researcher, this is an absolutely exceptional gold mine. Indeed, the robustness of these large-scale studies largely depends on the quantity and quality of available data. And with more 10 million soldiers who have all benefited from regular and strictly regulated blood tests, Harvard researchers could hardly have hoped for better.

Among all these soldiers, 955 cases of multiple sclerosis have been identified; unsurprisingly, all of them – except one – presented specific antibodies which testify to the passage of EBV. By compiling all the data at their disposal, the researchers determined that Epstein-Barr multiplies by 32 the risk of declaring multiple sclerosis. There is therefore no longer any doubt: EBV therefore plays a central role in the onset of this disease.

What we already know is that it is a autoimmune disease; the virus causes certain agents of the immune response to attack the myelin sheath. Very briefly, the latter is a structure that covers the axons (the “arms”) of neurons; it is essential both for protect, but also to ensure the fast and reliable transmission of the electrical signal in the nervous system. It is the deterioration of this sheath by the immune system that causes a whole range of serious neurological disorders.

Towards an anti-Epstein-Barr vaccine?

But the beginning of the mechanism still remains very mysterious. The research team remains very cautious at this level. The data clearly show that not all EBV infections cause multiple sclerosis; the virus is extremely common, affecting 90-95% of adults. But fortunately, multiple sclerosis is much less common. So that means there are bound to be other factors at play.

From now on, the challenge will therefore be to understand how these external genetic or environmental factors (smoking, diet, etc.) favor the development of the disease. Ultimately, the goal is to produce a treatment for multiple sclerosis; but the simplest thing might even be to pull the rug out from under it by eradicating the virus that causes it. The researchers believe that this work could serve as the basis for an anti-Epstein-Barr vaccine; this would make it possible to get rid of diseases such as mononucleosis, but also to escape multiple sclerosis according to this work. Moderna and Pfizer have already announced studies on this topic; if conclusive, the first results of these clinical trials could change the lives of millions of patients.

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