November 9, 2011
Researchers from Harvard School of Public Health (HSPH), Walter Reed Army Institute of Research, and their collaborators have found more evidence that infection with the Epstein-Barr virus (EBV) appears to significantly increase the risk of developing multiple sclerosis (MS). In a study including 222 MS cases and 444 controls, increasing levels of EBV antibodies prior to the onset of MS was associated with an increased risk of MS. Those with the highest levels had a 36-fold increased risk compared to those with the lowest EBV antibody levels. These findings, published in the October 2011 issue of Multiple Sclerosis Journal, build upon previous studies by these researchers and others showing a link between MS and the common EBV virus. Read the abstract.
“Our latest study shows for the first time that the association of EBV exposure and MS is consistent across sex, race, and age groups and strengthens the evidence that EBV is associated with MS,” said lead author Kassandra Munger, research associate in nutrition at HSPH.
The study builds upon nearly a decade of research by Alberto Ascherio, senior author of the study and professor of epidemiology and nutrition at HSPH, and colleagues. As early as 2001 they found that EBV may be linked to MS. A 2010 study showed the first conclusive evidence of the link.
EBV is a herpes virus and one of the most common human viruses worldwide. Infection in early childhood is common and usually asymptomatic. When people are older, however, EBV often causes infectious mononucleosis. In the U.S., upwards of 95% of adults are infected with the virus, but free of symptoms. EBV has been associated with some types of cancer and can cause serious complications when the immune system is suppressed, for example, in transplant recipients. There is no effective treatment for EBV.
According to the National Institutes of Health, approximately 250,000 to 350,000 people in the United States have been diagnosed with MS, a chronic degenerative disease of the central nervous system. Women are more likely than men to get the disease and it is the most common neurologically disabling disease in young adults. Although genetic predisposition plays an important role in determining susceptibility, studies have shown environmental factors equally important.
In the latest study, the researchers conducted a prospective study using blood samples from the Department of Defense Serum Repository. Pre-MS onset blood samples in 222 US military personnel who developed MS after joining the military were compared with those from 444 participants in a control group matched by age, sex, and race/ethnicity. The researchers found a consistent increase in MS risk associated with an increase in EBV antibodies in men and women, and those individuals with the highest levels of these antibodies had a 36-fold increased risk of MS as compared to those with the lowest.
These findings may spur new efforts to develop an effective EBV vaccine, and further research to determine if EBV exposure can be used as part of a “risk score,” a list of factors that may be used to identify those at a higher risk for MS, Munger said.
The study was supported by a grant from the National Institute of Neurological Disorders and Stroke.
“Anti-Epstein-Barr Virus Antibodies as Serological Markers of Multiple Sclerosis: A Prospective Study Among United States Military Personnel,” KL Munger, LI Levin, KI Falk, Alberto Ascherio, Multiple Sclerosis Journal, October, 2011