This Virus, Exposed to 90% of People by Age 40, May Trigger Sclerosis Development

In January 2022, the study led by Alberto Ascherio, epidemiologist at the Harvard Th, began a decisive turning point. By operating an exceptional database, that of ten million American soldiers followed between 1993 and 2013, the researchers were able to analyze the serological evolution of healthy individuals at the time of their enrollment. The samples taken every two years made it possible to follow the appearance of the virus in their blood, and to identify, among them, those who have later developed multiple sclerosis.

When the immune system turns against the brain

Among the 801 soldiers who became sick and with usable samples, 35 initially had no infection marker by the Epstein-Barr virus. All, except one, have become positive before the first symptoms appear, with an average period of five years. This figure, put in perspective with a control group that has been mainly seronegative over the same period, results in a striking observation. The risk of developing multiple sclerosis is multiplied by 32 in the event of infection, an order of magnitude comparable to the effect of smoking on lung cancer, as Science underlines in its article.

This strong link does not erase the complexity of the disease. The multiple sclerosis results from an excitement of the immune system, which attacks myelin, this insulating sheath of nerve fibers. The degradation of this layer disrupts the transmission of nerve impulses, causing motor, sensitive or visual disorders. If the causes remain multifactorial, between genetics and environment, the role of the virus as an initial trigger now seems difficult to ignore.

The researchers also observed an elevation of a neuronal degradation marker just after the infection. This biological signal strengthens the idea that the virus could initiate a specific autoimmun process. For the neuroimmunologist Lawrence Steinman, who comments on the study in Science, this discovery represents a major advance, even if other elements must still be clarified to understand why only a minority of infected people develops the disease.

Towards a preventive vaccination against multiple sclerosis?

If the Epstein-Barr virus stands out as an almost essential trigger factor, the idea of preventing infection to limit the appearance of the disease is gaining ground. An effective vaccine could radically transform the future care of sclerosis into plates, like what papillomavirus vaccination has allowed in the prevention of certain cancers.

Several tracks are already being studied. Moderna is developing a messenger RNA vaccine targeting four virus proteins. For his part, the virologist Jeffrey Cohen tests a version based on nanoparticles reproducing one of the key viral proteins. In the past, Glaxosmithkline had tried the approach with a viral envelope protein, without being able to prevent infection despite a reduction in mononucleosis.

The feasibility of large-scale vaccine prevention will not only depend on the effectiveness of formulations but also their ability to stop the autoimmun process. To validate this hypothesis, long -term clinical trials will have to follow young vaccinated and high risk adults, especially because of their genetic predisposition.

Despite the current absence of curative treatment, recent advances rebuild the cards. By highlighting the central role of the Epstein-Barr virus, research traces a path to a new era of understanding and, perhaps, of prevention of multiple sclerosis.