New study sheds light on how Epstein-Barr virus may contribute to multiple sclerosis - Medical Xpress

What the report says

Medical Xpress reported on July 18, 2026, that a peer-reviewed study in Science Translational Medicine identifies a possible immune pathway connecting Epstein-Barr virus, or EBV, to multiple sclerosis. MS is an autoimmune disease affecting the brain and spinal cord, and EBV has long been associated with it; the article notes that almost all people diagnosed with MS show signs of prior EBV infection, while most people infected with EBV never develop MS.

The researchers compared blood samples from untreated MS patients, people receiving MS therapies and healthy volunteers. In laboratory tests, they exposed immune cells to EBV proteins from different phases of the virus’s life cycle. The study found that people with untreated MS had roughly double the CD4+ helper T-cell response to EBV late-stage viral particle proteins compared with healthy volunteers. CD4+ T cells help direct inflammation, which is relevant because MS involves immune attacks on myelin, the protective layer around nerves.

Medical Xpress reported that the response appeared specific to EBV: when scientists tested two other common herpesviruses, people with MS and healthy participants reacted similarly. The mechanism still does not fully explain how those T cells may contribute to myelin damage, so the finding is not presented as proof that EBV alone causes MS.

The study also looked at patients starting anti-CD20 therapies, which deplete B cells, the cells where EBV can persist after infection. After treatment began, the heightened CD4+ T-cell responses declined by about 2.5-fold. The findings may help explain why EBV remains a major focus in MS research and could inform future work on immune targets and treatment response.