Multiple sclerosis (MS) is a chronic inflammatory disease that affects your central nervous system. This includes your brain and spinal cord. When you have MS, your immune system attacks the protective layer that surrounds your nerve cells. Sometimes these cells die.
MS has no cure, but scientists are close to finding out what triggers it. Strong evidence shows that viruses can trigger the process, especially the Epstein-Barr virus (EBV). This research could guide scientists to new and better ways to treat or prevent MS.
What is the Epstein-Barr virus (EBV)?
EBV is a type of herpes virus usually transmitted through saliva. Most people are infected with it during childhood, when they cause few or no symptoms. But EBV is the leading cause of infectious mononucleosis, aka mono. Mono usually appears in teenagers and young adults.
Symptoms of EBV infection include:
- Sore throat
- Swollen lymph nodes in your neck
You can spread EBV for only a few weeks. But like other herpes viruses, an inactive version will remain in your body. This “latent” virus can become active again later. You may or may not have symptoms if this happens.
There is no vaccine or cure for EBV.
What does the research say about the Epstein-Barr virus and MS?
Scientists have long suspected that EBV infection plays an important role in the development of MS. A causal link was difficult to prove. But new research offers strong evidence that the two are linked. This scientific data comes from two new studies, including:
The Harvard study. To test the EBV theory, a research team led by scientists from the Harvard TH Chan School of Public Health looked at data from more than 10 million young adults serving in the US military. Of this group, 955 were diagnosed with MS during their 20-year service period.
On average, MS symptoms began about 10 years after the first blood sample was taken.
The researchers knew the EBV infection status of 801 people who had developed MS. They discovered this by testing blood samples taken every two years after each person began military service.
The results of the study show:
- Symptoms of MS started about 5 years after the first positive EBV results.
- The odds of developing MS were increased 32-fold after infection with EBV.
- Other viruses did not increase MS risk.
- Only one person who developed MS remained EBV-negative.
The team also looked at changes in the neurofilament light chain (NF-L). It’s a protein that helps support your nerve fibers, or axons. NF-L ends up in the fluid around your brain and spinal cord when a disease like MS damages and destroys the outer layer of your nerves.
NF-L is a common sign, or biomarker, for diseases that weaken or destroy nerve tissue. And for those who developed MS, the researchers found that NF-L levels only increased after EBV infection.
The study did not examine whether EBV causes active disease or flare-ups in people who already have MS. He measured or compared NF-L samples before, during and after an MS diagnosis. The study measured disease activity.
The Stanford Medical Study. This team found evidence of what is called molecular mimicry. This is when the immune system targets germs and healthy cells because it cannot tell the difference between the two. This is commonly used to explain, at least in part, how viruses can cause MS.
The Stanford study found that 20-25% of people with MS make antibodies that bind to both a protein made by EBV and a protein made by the brain and spinal cord.
Here’s how this molecular confusion could trigger MS:
When you are infected with EBV, certain white blood cells begin to fight against EBNA1, or EBV nuclear antigen 1. But to the body, this viral protein may look a lot like the one in your central nervous system called the glial cell adhesion molecule, or GlialCAM. .
GlialCAM is a key protein inside your myelin, or the protective covering around nerve cells.
Researchers have found that for some people with MS, antibodies against EBNA1 are ‘cross-reactive’ with GlialCAM. As a result, the immune system can destroy both EBV proteins and a significant portion of healthy nerve cells.
Does the Epstein-Barr virus cause MS for sure?
The Harvard study stopped short of saying that their results directly prove that EBV triggers MS. But they suggest their findings cannot be explained by any other known risk factors for MS. That leaves EBV as the most likely cause.
Stanford Medicine scientists say their study is the first to ‘definitely’ show that EBV can trigger MS in some people.
What does the EBV link mean for the treatment and prevention of MS?
These studies support the idea that antiviral drug treatments that target EBV may be able to treat MS.
One of the best treatments for MS right now is something called anti-CD20 monoclonal antibodies. It is a treatment that reduces immune cells called memory B cells, where inactive EBV mainly lives. When you get rid of these white blood cells, you also get rid of at least one inactive EBV infection.
If EBV causes MS, scientists may be able to use this information to determine how to prevent MS in the first place. And research from the Stanford study suggests vaccine makers may need to avoid certain antigens, such as EBNA1, that could trigger an autoimmune reaction.
In the future, people who already have MS may be able to receive a “reverse vaccine”. Much like an allergy vaccine, it would teach the immune system to stop attacking GlialCAM in nerve cells.
If you have EBV, should you be worried about MS?
About 95% of people will catch EBV at some point. But most infected people do not develop MS. It’s rare. On average, MS affects about half of 1% of the population. In other words, there are over 332 million people living in the United States, and about 1 million of them could get MS. But almost all will have EBV.
Experts believe that an EBV infection, such as mono, is a necessary step towards the development of MS. But this is not the only factor. Your genes, biology, environment, and lifestyle also matter.
Your chances of developing MS may increase if you have a mixture of the following:
- You are a woman.
- You have a close family member with MS.
- You smoke.
- You have a history of migraine.
- You have very low levels of vitamin D.
Talk to your doctor about your concerns about EBV and MS. They will help you keep an eye on your health. And if you do develop MS, early drug treatment can help manage symptoms and slow disease progression. You may have even more treatment choices.
Not sure if you’ve had EBV? Tell your doctor. A simple blood test can tell you for sure.