The Epstein-Barr virus (EBV) is a herpesvirus transmitted in saliva and linked to certain cancers and autoimmune diseases. Most people carry EBV for life, yet multiple sclerosis (MS) affects under 1% of the population. New research helps explain why only some infected people develop MS: genes matter.
MS arises when the immune system attacks myelin, the insulating sheath around nerve fibers, causing vision, sensory, bladder, bowel and eventually respiratory problems. Current treatment suppresses immunity; preventing MS would be far preferable.
An international team of researchers from China, Germany, Switzerland and the UK found a likely mechanism involving a genetic molecule called HLA-DR15. HLA molecules sit on cell surfaces and present internal protein fragments to the immune system, guiding its recognition of self versus foreign material.
When B cells (antibody-producing white blood cells) are infected by EBV they normally present viral fragments to other immune cells. Some viral fragments closely resemble a myelin protein. In people carrying HLA-DR15, EBV can also induce infected B cells to present the myelin protein itself — a protein that normally has no place in a B cell. This “molecular mimicry” and aberrant presentation can train the immune system to attack myelin, causing MS.
HLA-DR15 is not a complete explanation: about half of MS patients have this allele, while roughly a quarter of people in northern Europe carry it and most never develop MS. Thus HLA-DR15 plus EBV increases risk but does not inevitably produce disease. Timing and environment matter: EBV infection in late childhood or early adulthood is particularly risky, and factors like poor diet, low vitamin D, smoking, pollution, shift work and obesity add risk.
A vaccine that entirely prevents EBV infection may be difficult because the virus is highly adapted to humans. However, vaccines that prevent symptomatic infectious mononucleosis (Pfeiffer’s disease) after infection—or that limit viral effects early in life—could reduce long-term MS risk. Several EBV vaccine candidates are currently in trials.
Researchers aim to translate the new mechanism into treatments. One approach under investigation is selectively eliminating immune cells that present EBV-derived fragments or that react to them, potentially benefiting MS patients with the HLA-DR15 genetic profile. Whether such targeted therapies will succeed remains to be seen, but the discovery gives scientists new tools and a clearer target in the fight against MS.
This article was originally written in German.