mysterious multiple sclerosis — Scientists debate the role of a virus in multiple sclerosis Recent study offers evidence of link between Epstein-Barr and multiple sclerosis.

Elizabeth Preston, Undark – Nov 25, 2022 11:00 am UTC EnlargeCHRISTOPH BURGSTEDT/SCIENCE PHOTO LIBRARY reader comments 8 with 0 posters participating Share this story Share on Facebook Share on Twitter Share on Reddit

Ryan Grant wasin his 20s and serving in the military when he learned that the numbness and tingling in his hands and feet, as well as his unshakeable fatigue, were symptoms of multiple sclerosis.Like nearly a million other people with MS in the United States, Grant had been feeling his immune system attack his central nervous system. The insulation around his nerves was crumbling, weakening the signals between his brain and body.

The disease can have a wide range of symptoms and outcomes. Now 43, Grant has lost the ability to walk, and he has moved into a veterans home in Oregon, so that his wife and children dont have to be his caretakers. Hes all too familiar with the course of the illness and can name risk factors he did and didnt share with other MS patients, three-quarters of whom are female.But until recently, he hadnt heard that many scientists now believe the most important factor behind MS is a virus.

For decades, researchers suspected that Epstein-Barr virus, a common childhood infection, is linked to multiple sclerosis. In January, the journal Science pushed that connection into headlines when it published theresultsof a two-decade study of people who, like Grant, have served in the military. The studys researchers concluded that EBV infection is the leading cause of MS.

Bruce Bebo, executive vice president of research at the nonprofit National Multiple Sclerosis Society, which helped fund the study, said he believes the findings fall just short of proving causation. They do, however, provide probably the strongest evidence to date of that link between EBV and MS, he said. Advertisement

Epstein-Barr virus has infected about 95 percent of adults. Yet only a tiny fraction of them will develop multiple sclerosis. Other factors are also known to affect a persons MS risk, including genetics, low vitamin D, smoking, and childhood obesity. If this virus that infects nearly everyone on Earth causes multiple sclerosis, it does so in concert with other actors in a choreography that scientists dont yet understand.

Amid that lingering uncertainty, scientists are discussing how to proceed from here. Antivirals or drugs that target infected cells, some of which are already in development, might help MS patients. Vaccines against EBV are in development, too. The authors of the Science paper say widespread vaccination could prevent most instances of MS. But other researchers arent so sure the case is closed, and they suggest putting more emphasis on understanding how the virus might interact with social factors such as stress.

Patients often want to know why this disease happened to them, said Lindsey Wooliscroft, a neurologist and associate director of research for the VAs Multiple Sclerosis Center of Excellence in Portland, Oregon. Its frustrating when I cant tell them.

Epstein-Barr most oftenstrikes in early childhood, with few or no noticeable symptoms. After the initial infection, the virus lurks inside certain immune cells for the rest of a persons life.

If someone avoids EBV until adolescence or adulthood, the virus is more likely to cause mononucleosis, an illness characterized by fever and fatigue. Mono is more common in Western countries, where kids encounter fewer germs early in life, said Alberto Ascherio, a professor of epidemiology and nutrition at the Harvard T. H. Chan School of Public Health and senior author of the Science paper. Advertisement

Like mono, multiple sclerosis ismost prevalentin the U.S. and parts of Europe. Scientists first suggested more than four decades ago that the two conditions might be linked. In the following years, the evidence piled up: Nearly everyone with multiple sclerosis has latent EBV in their cells. People who recall being sick with mono have a heightened risk of MS. Immune cells harboring the virus are more prevalent in the brains of MS patients.

Weve long suspected that Epstein-Barr virus had a role in the development of MS, Wooliscroft said. But its just been very hard to prove.

The surest way to prove causation would be to start with a group of healthy, uninfected adults and divide them at random into two groups. Researchers would infect just one group with the virus and then monitor both groups afterward to see who develops MS.

In the real world, such an experiment isnt ethical. Ascherio and his coauthors wanted to do the closest possible thing: find a group of people who hadnt yet been infected with EBV at a given time point, then see whether those who eventually did get infected were more likely to develop MS. Conceptually, our study is very simple, Ascherio said. In practice, it seemed virtually impossible to conduct.

Thats because the scientists would need a large number of study participants to monitor over the course of years, as MS can be slow to develop and diagnose. For help, the research team turned to the US military, which collects regular blood samples from active service members for HIV screening. In the end, it took two decades for the team to accrue enough data to perform its statistical analysis. Page: 1 2 3 Next → reader comments 8 with 0 posters participating Share this story Share on Facebook Share on Twitter Share on Reddit Advertisement Channel Ars Technica ← Previous story Next story → Related Stories Today on Ars