Back in April 2006, researchers from Harvard School of Public Health, Kaiser Permanente, and a team of collaberators found more evidence confirming that the Epstein Barr Virus is a contributory cause to MS.
EBV is a herpes virus and one of the most common human viruses worldwide. Infection in early childhood is common and usually asymptomatic. Late age at infection, however, 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.
The study’s main finding was that antibodies—proteins produced by the body to fight infection—to the Epstein-Barr nuclear antigen (EBNA) complex and its component EBNA-1 in individuals with MS were elevated up to 20 years before the first symptoms of the disease and persisted thereafter. Lead author Gerald N. DeLorenze, Ph.D., Kaiser Permanente Division of Research, and his colleagues cite three other studies—the Nurses’ Health Study, a U.S. army personnel study, and a study in Vasterbotten County, northern Sweden—that also showed a similar finding, but none of the previous studies could draw data from blood samples collected two decades or longer before the onset of MS symptoms.
Although there is strong evidence of an association between EBV and MS risk, researchers are still uncertain how the Epstein-Barr virus contributes to the inflammation of the myelin—the protective coating around the nerve fibers—that leads to the debilitating disease. The fact that EBV infects B-lymphocytes, cells of the immune system that are part of our defenses against infection, seems to fit with the evidence of immune dysfunction in MS, but rigorous work remains to be done to unravel the molecular mechanisms.