Epstein-Barr Virus Might Kick-Start Multiple Sclerosis

Researchers have found that patients with multiple sclerosis (MS) carry a population of immune cells that overreact to Epstein-Barr virus. The virus, which causes mononucleosis and may contribute to some cancers, has long been suspected to play a role in MS. However, the mechanism linking the virus to the disease was poorly understood.

Scientists think that MS - which can cause vision problems, muscle weakness, and difficulty with coordination and balance - is a result of the immune system attacking the body's own nervous system. Not everyone who is infected with Epstein-Barr develops MS, but the results of the new study, published in the June 2006, issue of the journal Brain, suggest that some individuals' unusually strong reaction to the virus may trigger the disease. The findings could lead to new therapeutic strategies for better control of the damage caused in this autoimmune disorder.

The culprit, the researchers say, may be a population of T cells that helps boost other components of the immune system in response to the virus. "What we discovered in the peripheral blood of the MS patients were T cells that appeared to be primed for action against EBV," said Nancy Edwards, an HHMI-NIH research scholar at the National Institutes of Health (NIH) and co-author of the paper, which was published in advance online.

HHM-NIH research scholars are medical students who are interested in research. They compete for the opportunity to spend a year conducting mentored research in NIH labs. The program is designed to encourage medical students to consider careers as physician-scientists. Edwards, a medical student at Duke University School of Medicine, conducted her research primarily in the laboratory of noted MS researcher Roland Martin at the National Institute of Neurological Disorders and Stroke.

"The susceptibility to acquire MS is inherited, but environmental insults such as viral infections are thought to trigger the disease, and Epstein-Barr virus is one of the leading candidate triggers," said first author Jan Lu"nemann, a neurologist and immunologist at The Rockefeller University in New York. "Epstein-Barr virus does not cause MS, but the immune response to this virus is different in MS patients, and our hypothesis is that the altered immune response contributes to the development and progression of the disease."

Lu"nemann started the research as a postdoctoral fellow at NIH. He is continuing to investigate the role of Epstein-Barr virus in MS in the lab of Christian Mu"nz, a Rockefeller University researcher who specializes in EBV-specific immune responses.

The people with MS, who are universally infected with Epstein Barr virus, showed increased antibody responses to certain EBV proteins in previous studies, Lu"nemann said. "Very recent investigations have shown that such enhanced responses occur years before onset of clinical symptoms of MS," he noted, indicating that EBV plays an important role early in the development of the disease.