The Epstein‑Barr virus (EBV) is a common herpesvirus spread through saliva and linked to some cancers and autoimmune diseases. Most people become lifelong carriers of EBV, yet multiple sclerosis (MS) remains rare. New international research suggests a key reason: certain genes shape how EBV influences immune responses, making some people more susceptible to MS.
MS results from the immune system attacking myelin, the insulating sheath around nerve fibers, which leads to vision problems, sensory and bladder disturbances and, over time, more serious disability. Current therapies suppress immune activity; preventing the initial autoimmune trigger would be a better strategy.
The new work implicates the HLA‑DR15 variant of the human leukocyte antigen (HLA) system. HLA molecules sit on cell surfaces and display internal protein fragments to immune cells, helping the body distinguish self from foreign proteins. When EBV infects B cells (antibody‑producing white blood cells), those B cells normally present viral protein fragments so other immune cells can respond. Some EBV fragments closely resemble a myelin protein. In people carrying HLA‑DR15, EBV infection can also cause B cells to present the myelin protein itself — a protein that B cells don’t normally show. That aberrant presentation, a form of molecular mimicry, can train the immune system to attack myelin and trigger MS.
HLA‑DR15 is not the whole story: about half of people with MS carry this allele, while roughly a quarter of people in parts of northern Europe do and most never develop MS. Thus HLA‑DR15 plus EBV raises the risk but does not guarantee disease. Timing and environment matter: EBV infection in adolescence or early adulthood is especially associated with higher MS risk, and factors such as poor diet, low vitamin D, smoking, pollution, shift work and obesity also increase susceptibility.
Completely preventing EBV infection is challenging because the virus is highly adapted to humans. Still, vaccines that prevent symptomatic infectious mononucleosis or limit EBV’s effects early in life could lower long‑term MS risk; several vaccine candidates are in trials. Researchers are also exploring therapies that selectively remove or neutralize immune cells that present EBV‑derived fragments or that react to them, a strategy that might benefit MS patients with HLA‑DR15. Whether such targeted treatments will work remains to be seen, but the discovery provides a clearer mechanism and new therapeutic targets.
This article was originally written in German.