April 26th, 2004
Boston Cure Project
Epstein-Barr virus (EBV), the virus that causes mononucleuosis, is considered a potential candidate as a cause or trigger of MS. A few studies of adults have found higher rates of past EBV infection in people with MS vs. non-MS controls. However, the fact that more than 90% of adults have been infected with EBV makes it difficult to substantiate this association.
To address this issue, a group of researchers at the Hospital for Sick Children in Toronto studied EBV exposure in children and adolescents. They analyzed EBV antibodies in a group of children with MS plus control groups consisting of healthy blood marrow donors and emergency department (ED) patients. They found that 83% of the MS subjects had antibodies indicating an EBV infection sometime in the past, compared with 42% of both sets of controls. Only 17% of the MS group had no antibodies against EBV, compared with 55% of the blood marrow donors and 36% of the ED patients. 22% of the ED patients had antibodies consistent with a recent EBV infection, which was expected since the symptoms that brought them to the ED were suggestive of EBV.
Antibodies to other viruses were also checked to see if there was a general correlation between MS and viral exposure. Antibody levels were similar in the MS and control groups to parvovirus B19, varicella zoster virus (chickenpox), and cytomegalovirus. Interestingly, 88% of the controls had been exposed to herpes simplex virus vs. only 52% of MS subjects. This may indicate that herpes simplex plays a protective role against MS.
Regarding the association between EBV and MS, the authors give three possible explanations:
(1) EBV infection may trigger or propagate MS disease processes;
(2) MS makes one more susceptible to EBV, or
(3) some other factor increases the susceptibility to both MS and EBV.
Of course, possibility (1) is of particular interest. One hypothesis
that has been raised is that similarities between certain EBV antigens
and myelin antigens causes the immune attack against EBV to turn into an
autoimmune reaction. Since not all of the pediatric MS subjects in this
study had exposure to EBV, the virus clearly is not required for the development
of MS. Nevertheless, this study certainly adds strength to the argument
that it may be involved in at least a subset of people with MS.
Copyright © 2004, Boston Cure Project