The researcher Diego Clemente, from the National Hospital for Paraplegics in Toledo, considers that the association of the Epstein-Barr virus with multiple sclerosis could open a door towards prevention in the population at risk.
Neuroimmuno-Repair Laboratory of the National Hospital for Paraplegics in Toledo where multiple sclerosis is investigated. EFE/Ana Soteras
Epstein-Barr virus and multiple sclerosis, a possible route to prevention
The biologist specifies that being infected with the Epstein-Barr virus is not a determining factor, but it is necessary or precipitating, to develop this chronic autoimmune disease.
This association between the virus and multiple sclerosis is what has been most convincingly proven by research carried out by the TH Chan School of Public Health at Harvard University in a macro-study that originally included ten million US soldiers from of which 955 were diagnosed with this inflammatory disease of the central nervous system.
Clemente specifies that this research demonstrates “a strong association” of the virus with the disease, but not exactly causality, since the origin of multiple sclerosis is also due to predisposing genetic factors and influencing environmental factors, such as vitamin D deficiency. , smoking or obesity.
The truth is that 95% of the population is infected with this virus (kissing disease is one of its consequences) but only a few develop multiple sclerosis, so it is not a determining factor. In Spain, about 2,000 cases are diagnosed each year, the majority in women.
“The most interesting thing about this study is that if this association is so strong” a path is opened for prevention in people with clear risk factors, says the director of the Neuroimmuno-Repair Laboratory of the National Paraplegic Hospital of Toledo.
It would be children or young people who have not developed the disease, which usually appears between the ages of 20 and 40, but who have risk factors such as siblings and parents with multiple sclerosis (although it is not a hereditary disease, there is a greater family probability). or certain mutated genes that predispose.
“If there were a vaccine against the Epstein-Barr virus and it was administered to these people at risk and they did not develop the disease, we would be demonstrating that this virus is the cause of the disease together with the other genetic and environmental factors to which they are exposed. these people”, points out the biologist.
Regarding the possibility of treating the ongoing disease with antivirals against this pathogen, Clemente indicates that it could be more effective in newly diagnosed patients than in long-term patients, since from the time the virus infection occurs until the disease emerges An average of five years passes and it is possible that this time plays against it, but it is something that is not yet known.
The relationship between the Epstein-Barr virus and multiple sclerosis has been the subject of research in previous studies, but this Harvard research is the one that most emphatically demonstrates this association by following up to 20 years of a group of recruits: of the 10 original million, 955 develop multiple sclerosis, 801 are followed up and only one is not infected with the virus but is still affected by the disease.
SEN specifies that the cause of multiple sclerosis is uncertain
The Spanish Society of Neurology (SEN) points out that, despite the study published in «Science», in which once again a possible association between the Epstein-Barr virus and multiple sclerosis seems to have been found, «it is not clear why multiple sclerosis manifests itself in some people and not in others».
Many studies have been carried out to try to identify which, or which, are the environmental factors directly related to the development of the disease without, until now, having been able to establish a definitively consistent relationship with any of them, he points out in a statement.
Currently, the cause of multiple sclerosis is unknown, although most of the studies carried out support the existence of environmental factors that, acting on genetically predisposed individuals, trigger the autoimmune phenomenon through which inflammatory and degenerative processes develop in the central nervous system.
The influence of these environmental factors seems crucial during childhood, as shown by studies carried out in populations that migrate from areas of low frequency of the disease to others of high risk, or vice versa, being able to modify the susceptibility to suffer from the disease so that The first two decades of life seem fundamental for establishing the risk of suffering from multiple sclerosis.
The disease does not follow a conventional inheritance pattern, associated with a single gene, but more than 200 genes have been identified that seem to give the individual a greater risk of developing it when exposed to the aforementioned environmental factors.
Among these environmental factors, vitamin D levels have been studied, in direct relation to exposure to ultraviolet radiation from sunlight, smoking, salt consumption, obesity in adolescence and exposure to different infectious agents such as the Epstein Barr virus (EBV).
For many years, the existence of infectious agents has been proposed that would increase the risk of multiple sclerosis if they were acquired in adolescence, but not if the first contact with them occurred during childhood.
Supporting this “hygiene theory” hypothesis, the epidemiological findings indicate that the prevalence of the disease is low in developing countries and tends to increase in regions with a higher socioeconomic status and sanitation, where the age of these primary infections is delayed.
Interestingly, the timing of primary infection with this virus is generally considered a marker of childhood hygiene and has been linked to an increased risk of developing multiple sclerosis.
Generally acquired in early childhood in developing countries, primary Epsteni-Barr virus infection is drastically delayed in developed areas, with a much lower seroprevalence in the young so that when it does occur, the risk of infection is significantly increased. develop infectious mononucleosis while in childhood the infection can present a very trivial or even asymptomatic clinic.
While several studies provide strong evidence that infectious mononucleosis is an important risk factor for developing multiple sclerosis, it is also true that the very high prevalence of EBV seropositivity in the general population (95%) and the relatively low frequency of incidence of Multiple sclerosis poses a great challenge to prove the direct causality between the risk of developing the disease and the previous viral infection.
According to the SEN, Epstein-Barr virus infection before the age of 15 could influence the risk of developing multiple sclerosis and this age dependency could be due to altered immune responses after contact with the virus in adolescence and old age early adulthood, but the fact that a person has developed an infection by this virus does not imply that they will necessarily develop multiple sclerosis since, as we previously pointed out, the disease is multifactorial.
Thus, they reiterate that research continues to point to a combination of genetic factors with other environmental factors and not just a single factor.
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