Epstein-Barr virus (EBV) has been repeatedly associated with multiple sclerosis and other autoimmune diseases. A study supporting this link has found abnormal accumulation of EBV infected B lymphocytes in the brain lesions of patients with multiple sclerosis.

Multiple sclerosis is the most common inflammatory disease of the central nervous system affecting young adults. Similarly to other chronic inflammatory diseases, like rheumatoid arthritis and systemic lupus erythematosus, multiple sclerosis is thought to result from an inappropriate attack of the immune system toward selected body components, a process named autoimmunity. In the case of multiple sclerosis, the immune system is thought to attack myelin, the lipid-rich sheath coating our nerves.

Image: Photomicrograph depicting leukemia cells that contain Epstein Barr virus.

To date neither the causes nor the cure of multiple sclerosis have been identified. Viruses have always attracted the interest of immunologists as possible triggers of autoimmune diseases due to their ability to interfere with the host’s immune system. EBV infects up to 95 % of the human population worldwide and has been repeatedly associated with multiple sclerosis through epidemiological and serological studies. The virus has the ability to hide in a particular population of immune cells, the B lymphocytes, remaining in a relatively dormant state for the entire life of the host. However, when not properly controlled by the immune system, EBV can reactivate causing tumors.

The researchers showed that EBV is present in brain lesions of patients with multiple sclerosis and that the virus is brought into the central nervous system by B lymphocytes, which behave as Trojan horses for the virus. They also showed that the infected B cells present in the brain become the target of an immune attack, thus promoting the chronic inflammation which leads to tissue destruction. This raises the suspicion that EBV and its Trojan horses are the main cause of brain damage in multiple sclerosis.

The researchers conclude that by shedding light on the involvement of EBV in multiple sclerosis, the findings will pave the way to disease prevention and future treatments.
References:
1. Salvetti M, Giovannoni G, Aloisi F. Epstein-Barr virus and multiple sclerosis. Curr Opin Neurol. 2009 Jun;22(3):201-6. PMID: 19359987.