Researchers from the Harvard School of Public Health, Kaiser Permanente, and a team of collaborators have found further evidence implicating the Epstein-Barr virus (EBV) as a possible contributory cause to multiple sclerosis. The study appears in the advance online edition of the June 2006 issue of Archives of Neurology.
MS is a chronic degenerative disease of the central nervous system. Although genetic predisposition plays an important role in determining susceptibility, past studies have shown that environmental factors are equally important.
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 percent 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 population was made up of more than 100,000 members of the Kaiser Permanente Northern California (KPNC) health plan, who provided blood specimens as part of medical examinations between 1965 and 1974. The KPNC maintained the medical records of all its members, including those who provided specimens, in electronic databases. Between 1995 and 1999, those databases were searched for evidence that would indicate a possible diagnosis of MS.
The researchers selected 42 individuals diagnosed with MS and that had serum specimens collected before the date of diagnosis. Two controls for each case were then selected from the serum database and matched by sex, date of blood collection, and age at time of blood collection.
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.
“Collectively, the results of this and the previous studies provide compelling evidence that infection with EBV is a risk factor in the development of MS,” said Alberto Ascherio, senior author of the study and associate professor of nutrition and epidemiology at Harvard School of Public Health.