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There are several theories on the role of EBV in the development of MS. These include:
Another important feature of EBV biology to be aware of:
Researchers have found that parts of the myelin and nerves have a similar structure to EBV.
One theory is that the body’s immune response against EBV also targets the brain and spinal cord, in a case of “mistaken identity”.
Normally, cells infected by a virus are killed by the immune system as part of the body’s surveillance and defence against infections. However, EBV has a unique ability to keep its host cell alive, by hijacking the cell’s internal processes to resist killing.
If EBV, by chance, infects an “autoimmune” cell that targets the brain and spinal cord, it may keep this cell alive, when it should normally be killed, allowing this cell to cause the damage seen in MS.
This theory also explains how the immune attack on the brain and spinal cord in MS is not shut down by the processes that normally prevent immune responses against our own body.
EBV-infected immune cells make higher levels of human inflammatory molecules, as well as viral molecules that can alter the immune response.
EBV also changes immune cells in ways that might promote their movement into the brain.
These changes to the immune response may be part of the process that leads to MS attacks.
Some studies have demonstrated the presence of cells infected with EBV in the brain of people with MS. Using post-mortem tissue, EBV has been found in areas of damage, known as MS lesions, in the brain of people with MS but not in people without MS.
The presence of EBV-infected cells in the brain could induce inflammatory immune responses, damaging brain tissue in the crossfire.
Not all studies have not been able to detect EBV in MS brain tissue, so more research is needed to resolve this question.
EBV infects B cells of the immune system and lies mostly dormant or relatively inactive in these cells for the rest of a person’s life. This phase is called “latent” infection or “latency”.
Periodically, the virus is “reawakened” to multiply and release new viral particles into the body, infecting new cells. This phase is called “lytic” infection.
The lytic phase may be important for maintaining EBV infection in the body.
During this phase, infectious virus can be detected in saliva, blood and other body fluids. People may or may not experience symptoms during lytic infection.
Antiviral medications work by stopping EBV from multiplying during its active phase.
They cannot kill EBV in its inactive phase.
For more information on treating EBV using antivirals in MS, see here.
