A team of researchers at Trinity College Dublin have developed a unique blood test to measure the immune response to the Epstein Barr Virus (EBV) which is the leading risk factor for developing multiple sclerosis (MS). Their findings are published in the journal Neurology Neuroimmunology and Neuroinflammation.

A range of viruses relating to MS have been studied in the past but none have had such compelling evidence as EBV. The question is why do some people who have known MS have a rogue immune response to EBV, a common viral infection that is generally asymptomatic?

To answer this, scientists measured the cellular response of MS patients to EBNA-1, a part of the EBV that can mimic the myelin coating of nerves which are the principal site of attack of the immune system in MS. The team found that the immune response is higher to EBNA-1 in people with MS compared to those with epilepsy, or the healthy control group. The team also showed that this cellular response is impacted by currently approved medications for MS which target the immune system, but not the virus. 

The immune response to EBNA-1 was found to be lower in people who are taking B cell depleting medications compared to people with MS not taking medication, and the level recorded was equivalent to healthy controls.  

B cell depleting medications are effective for reducing MS disease activity. It is not known however, how exactly they work. Many people believe that reducing B cells reduces EBV levels, as EBV can lie dormant within B cells. The scientists do not prove this theory, but do show that the immune response to EBV in MS is equal to healthy controls when these medications are used.

The team believes that this supports the need for more selective reduction in EBV rather than targeting all B cells. This is of importance as B cells play an important role in fighting infection and an unselective approach can lead to unwanted side effects.

The Trinity researchers are the first team of scientists to capture the immune response to EBNA-1 using whole blood samples carried out exclusively with equipment that is used in the hospital laboratory day to day. This builds on previous research that used extensive pre-processing in research laboratories.