Epstein-Barr Virus (EBV) and MS
Scientific research has shown that the Epstein-Barr virus (EBV) significantly increases the odds of developing MS.
What is Epstein-Barr virus?
Epstein-Barr virus (EBV) is a very common type of herpes virus. Nine in ten adults will be infected with EBV in their lifetime. Usually, it causes no symptoms. In some people, EBV causes glandular fever, also known as mono (short for infectious mononucleosis).
EBV mainly infects cells in our immune system. It infects one type of immune cell and forces it to become a certain type, called memory B cells. These hide and stay in our immune system for the whole of our lives. So, after infection, EBV lies dormant in our bodies for as long as we live. It occasionally shows itself when it makes more EBV virus.
EBV symptoms can include:
- Sore throat
- Swollen glands
- A high temperature
- Headaches
- Tiredness
- Rash
The link between Epstein-Barr virus and multiple sclerosis
For several decades, we’ve known there’s a link between EBV and MS. Especially for symptomatic EBV infection (glandular fever, or mono). EBV infection isn't enough to cause MS on its own. But there’s significant evidence of a link between Epstein-Barr virus and MS. We think this is a combination of genetic and environmental factors.
Research hasn’t definitively proved that EBV causes multiple sclerosis. It could be that MS in fact makes you more likely to become infected with EBV, rather than the other way round. Or it could be that underlying genetic differences make you more likely to have both EBV and developing MS.
Most people are infected with EBV at some point and most people won’t develop MS.
Read more about the causes of MS
What does EBV do in MS?
We don’t yet fully understand what might lead from EBV infection to developing MS. Research has shown several possible pathways. It could also be a combination of these.
EBV might trigger immune activity leading to MS
Infection with viruses like EBV starts an immune response. We think in some people, this triggers the immune cells and leads to a cascade leading to MS. This may only happen in some people because of their genetics.
Some people with MS have different versions of certain genes. For example, genes that make human leukocyte antigens (HLA) on the surface of cells. The HLA found on body cells tell your immune system they’re part of you, so they’re not attacked. HLA also tell the immune system when the cells are invaded by infection.
EBV can use the HLA to infect immune cells. Some versions make it easier for the virus to infect the cells. From genetic studies we know these versions are more common in people who get MS.
Some versions of the HLA might make you more susceptible to immune cell attack. Then, when EBV infects it causes the immune system to react excessively.
Immune cells might mistake myelin for EBV
After a viral infection, immune cells remember what the virus looks like to attack it again. The immune cells could be mistaking myelin for EBV. Research shows parts of myelin look similar to parts of the EBV virus. Some people with MS have antibodies that grip on to both a part of the EBV virus and also part of myelin. Other people have immune cells that recognise EBV and myelin or other nerve proteins.
EBV might drive MS through immune cell infection
We know EBV stays dormant in immune cells after infection. These immune cells last throughout our lives. In MS, it’s these immune cells which mistakenly attack myelin.
So, EBV could be continuing to influence the cells long after infection. Researchers think it does this by hijacking certain normally inactive parts of the genetic code. The activated immune system might become misdirected and attack myelin.
The dormant EBV hiding inside could be pushing a type of immune cells called B cells to attack myelin. Most existing disease modifying therapies (DMTs) work by killing or stopping all B cells. Perhaps the most important ones to kill are the EBV-infected B cells.
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