How the Epstein-Barr virus may spur the progression of multiple sclerosis

The underlying causes of MS have been a puzzle for scientists for decades.

“It’s not really clear what’s driving the disease process, what’s keeping it going,” Dr. John Lindsey, a neurologist and interim director of the Division of Multiple Sclerosis and Neuroimmunology at McGovern Medical School at UTHealth in Houston who was not involved in the study, told Medical News Today.

“Compared to the general population, there’s not a noticeable immune system problem in people with MS, so we’re left with the knowledge that it’s an unusual response to whatever stimulus that is making the immune system go off and attack the brain and spinal cord,” he explained.

It’s also difficult to predict the course of the disease, with effects ranging from mild to severe. Lindsey said there’s a large range of outcomes for a person who’s diagnosed.

“Some people will have a very aggressive course and become disabled in a few years, while others will have a more benign course with occasional symptoms but won’t develop any significant disability,” Lindsey said.

The Epstein-Barr virus is a type of herpes virus and is prevalent.

In fact, most people will be infected with it at some point. It generally doesn’t cause symptoms, although it can cause other illnesses, including mononucleosis.

EBV is also associated with the development of MS, even though the vast majority of people with EBV will not develop MS. It’s believed that when combined with other environmental and genetic risk factors, EBV has a causal role in the development of MS.

Olivia Thomas, a postdoctoral researcher in the Department of Clinical Neuroscience at Karolinska Institute and shared first author of the paper, told Medical News Today that she and her colleagues sought to better understand this connection.

“The mechanism through which EBV contributes to MS is not fully understood. In fact, there are currently several theories which have been suggested but so far there is no consensus in the field,” Thomas explained.

“It is most likely a combination of several of the current theories or, as there is so much disease heterogeneity between MS patients, there may even be different mechanisms between individuals who develop MS,” she added.

The researchers say they found an intriguing wrinkle in the relationship between EBV and MS.

They note that the same antibodies that some people’s bodies produce to fight EBV can also have a detrimental effect when it comes to the development of MS.

“The immune response to EBV, rather than fighting infection, instead has the potential to damage the brain and spinal cord,” said Thomas. “This could be the mechanism behind EBV’s involvement in development of MS.”

The researchers said these antibodies bind to EBNA1, a protein in EBV, which in turn helps fight off EBV infection. However, these same antibodies can also become misdirected and bind to a similar protein in the brain and the spinal cord, which has the effect of damaging the nervous system and fueling the growth of MS.

“Molecular mimicry is when two structurally similar but distinct antigens are able to activate the same immune cell,” Thomas explained. “So when the immune system generates an immune response to fight infection, in some individuals it is also able to damage the brain and spinal cord, leading to the symptoms that patients experience.”

Thomas and her colleagues intend to expand their research in order to better understand how the body’s T cells – white blood cells in the immune system – fight EBV infections and, conversely, how these cells can damage the nervous system and in turn fuel the progression of MS.