Behind the Headlines
Multiple sclerosis (MS) is the most common demyelinating disease in humans. You may have come across the myelin sheath when studying neurons in GCSE or A-level Biology. It is a fatty, insulating layer that surrounds the axons of neurons and helps nerve conduction (perhaps think about why this aids this function!). It is produced by Schwann cells in the peripheral nervous system and by oligodendrocytes in the central nervous system (brain and spinal cord).
MS is thought to be an autoimmune condition - i.e. where the body’s own immune system attacks certain structures. In this case, T cells cross the blood-brain barrier, recognise myelin as ‘foreign’, and attack it. There can be a broad range of symptoms, including vision problems, altered sensation, muscle weakness and problems with coordination. It is a debilitating disease, and can reduce life expectancy by up to 5-10 years.
The aetiology (a fancy word roughly meaning ‘cause’) is not well understood. This has meant it has been very difficult to treat, with drugs mainly being used for symptom relief (muscle relaxants, painkillers etc).
The article linked above references a recently-published study (which you can read here if interested: https://www.science.org/doi/10.1126/science.abj8222, but don’t worry if you don’t fully understand it, it is well above even undergraduate level!). They found using a 20-year-long study of over 10 million members of the US military that infection with Epstein-Barr virus (EBV) appeared to increase the likelihood of developing MS by 32 times, an effect that was not seen with other viruses.
EBV is best known as the cause of infectious mononucleosis, which you might know as ‘glandular fever’ or ‘mono’. However, Epidemiological studies show that over 95% of adults worldwide have been infected with EBV, whereas only 2.8 million people are estimated to have MS globally. Therefore, it is clear that not all those infected by EBV develop MS, but the correlation between the two seems significant. This does not seem to be the case with other viruses investigated by the same study.
What do you think the implications might be for our treatment of MS if we establish it to be linked to a virus such as EBV?
If you’re interested, you can watch a 2-minute introductory video about MS here: https://www.youtube.com/watch?v=c_TPwZDo2Yo.
If you want more detail, this is a slightly longer video (but is at a medical school level, so don’t worry if you don’t understand it yet!): https://www.youtube.com/watch?v=yzH8ul5PSZ8.
You can see a patient’s perspective of MS here: https://www.youtube.com/watch?v=_aa2hKL0A_o.
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