Epstein-Barr virus: Its underestimated role in Multiple Sclerosis

Epstein-Barr virus (EBV), also known as Human herpesvirus 4, is one of the most widespread infections in the Herpesvirus family, infecting approximately 90% of the global population^[1]. Despite its prevalence, EBV typically leads to mild or even asymptomatic infections. When symptoms do appear, they often mimic common childhood illnesses, presenting as fever, sore throat, and rashes^[2]. The virus spreads mainly through saliva, making activities like kissing or sharing food and drinks common transmission methods^[2].

While EBV often causes no serious health issues, recent studies have suggested a potential link between EBV infection and the development of Multiple Sclerosis (MS), an autoimmune disorder. MS occurs when the immune system mistakenly attacks the myelin sheath — a protective insulating layer around nerve cells in the brain and spinal cord. This sheath, composed of fats and proteins, is crucial for the rapid transmission of electrical signals between neurons, a process known as saltatory conduction, which allows messages to efficiently ‘jump’ along nerve fibres^[3].

While the exact relation between MS and EBV remains unknown, one theory suggests that EBV might produce components that closely resemble parts of myelin sheath. This mimicry can  confuse the immune system, leading it to wrongfully attack the myelin and compromise its integrity, hampering nerve communication^[4].

Another theory explains that EBV might stay inactive in certain immune cells called B cells, which are part of the body’s defence system and typically do not reside in the brain. However, upon reactivation of the virus, these infected B cells could migrate to the brain, where their presence could trigger an immune response that damages the myelin^[5].

It is crucial to note that although almost everyone encounters EBV at some point, only a small fraction of infected people (20-25%) develop MS^[6]. This shows that other factors play a significant role in the development of the disease that should not be overlooked. Understanding the mechanism by which EBV might trigger the immune response to attack the myelin sheath could be valuable for discovering future treatments for MS. Indeed, there have already been some suggestions, such as a vaccine against EBV and therapeutical targets which kill infected B cells before they travel to the brain^[7].

[1] https://www.sciencedirect.com/science/article/abs/pii/S1567134819302084

[2] https://www.cdc.gov/epstein-barr/about/index.html

[3]https://www.nhs.uk/conditions/multiple-sclerosis/#:~:text=Multiple%20sclerosis%20(MS)%20is%20a,it%20can%20occasionally%20be%20mild.

[4] https://pubmed.ncbi.nlm.nih.gov/2414848/

[5] https://www.science.org/doi/10.1126/science.abm7930

[6] https://med.stanford.edu/news/all-news/2022/01/epstein-barr-virus-multiple-sclerosis.html

[7] https://www.science.org/doi/10.1126/science.abm7930

Edited by Hazel Imrie

Copy-edited by Rachel Shannon