Written by Amy Norton HealthDay Reporter >
Friday, January 14, 2022 – For years, researchers have suspected that the Epstein-Barr virus, known to cause multiple sclerosis, may also play a role in causing multiple sclerosis. Now a new study reinforces the case.
The study, which included more than 10 million members of the US military, found that the risk of developing multiple sclerosis (MS) increased 32-fold after infection with Epstein-Barr.
Epstein-Barr virus (EBV) is ubiquitous, with about 95% of the population infected at some point. Many people get it as children, while it usually does not cause any symptoms. When people become infected in their teens or young adults, it can cause mononucleosis.
Over the years, a number of studies have hinted that in a small number of people, EBV may help increase the risk of developing multiple sclerosis. MS is a neurological disease caused by the immune system’s misguided attack on the body’s nervous tissue.
People who have had mononucleosis, for example, are more likely to develop MS than those who have never had symptoms of an EBV infection. Meanwhile, people with MS can show high levels of antibodies against EBV several years before their symptoms appear. The researchers also found EBV-infected B cells in the brains of multiple sclerosis patients.
All of which suggests that something about the immune response to EBV infection can, in some people, spur the development of MS.
But proving that the virus is a cause of MS, and not just a bystander, has been a challenge. This is partly because nearly everyone has EBV, while MS is relatively rare.
It takes an extensive, long-term study to identify people who are EBV-negative initially, and then find out whether new EBV infections increase the risk of developing MS later.
The new study published in the journal Science, He did exactly that.
“This is the strongest evidence we have to date that EBV contributes to MS,” said Mark Allegreta, vice president of research at the nonprofit National Multiple Sclerosis Society.
Allegreta, who was not involved in the study, said the virus is likely “necessary, but not sufficient” to cause MS. That is, it conspires with other factors that make people more likely to develop MS.
At this point, studies have identified some other factors associated with a higher risk of multiple sclerosis, said study lead author Dr. Alberto Acherio.
These include certain genes, as well as smoking, vitamin D deficiency and childhood obesity, said Achirio, MD, professor of epidemiology at Harvard Medical School.
None of those factors, however, come close to a 32-fold increase in risk associated with EBV infection, Ashrio said.
He described the latest findings as “conclusive evidence” of the virus’s role in causing multiple sclerosis.
In the study, US military personnel were tracked for more than 20 years. All blood samples were taken at recruitment, and then every two years.
Ascherio’s team found that about 5% were EBV negative at the time of the first test.
Overall, 955 military personnel were diagnosed with MS while on active duty. This included 35 people who were initially EBV negative. All but one of these people had been infected with EBV before their MS diagnosis—usually five years before.
Compared with their counterparts who remained negative for EBV, people newly infected with the virus were 32 times more likely to develop MS during the study period.
One question is whether people in the presymptomatic stages of MS have a compromised immune system that makes them more susceptible to viral infections in general.
So Ascherio’s team looked at whether the risk of MS was linked to other viral infections in the military, including cytomegalovirus – another common virus that remains dormant in the body for life. They did not find a similar link between those viruses and MS.
It’s possible, Ascherio said, that something about the immune response to EBV, specifically, helps trigger MS. Exactly what remains unclear.
An editorial published with the study echoed the idea that EBV is necessary, but not sufficient by itself, to cause MS.
Dr. says. William Robinson and Lawrence Steinman of Stanford University in California.
They have raised the question of whether vaccinations against EBV can help prevent MS. Such vaccines are in development: Moderna, the manufacturer of one of the RNA COVID vaccines, has started an early trial of an mRNA vaccine against EBV.
Another possibility, Ascherio said, is that antiviral drugs that target EBV-infected cells could be tested to treat MS.
Some newer MS medications slow the progression of the disease by depleting certain B cells in the body. Allegretta said it’s “reasonable” to speculate that one reason the drugs work is to reduce EBV-infected B cells.
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Posted Jan 2022