Researchers at the University of California, San Francisco have discovered new evidence of how the Epstein-Barr virus (EBV) contributes to multiple sclerosis (MS).[1] A study published February 5 in the journal Nature Immunology showed that people with MS have higher levels of specific CD8+ "killer" T cells, which normally destroy infected or damaged cells.[1] The researchers compared blood and cerebrospinal fluid samples from 13 people with MS or early symptoms of the disease and from five healthy people.[1] In MS patients, EBV-reactive T cells were between 10 and 100 times more concentrated in the cerebrospinal fluid than in the blood, suggesting abnormal immune activity in the nervous system.[1] EBV was detected in the cerebrospinal fluid of most participants regardless of whether they had MS, but one viral gene was only active in people with MS, suggesting its role in impaired immune response.[1] Researchers have already begun testing treatments that target the virus directly, hoping they could help not only MS but also other autoimmune diseases, including lupus and rheumatoid arthritis.[1]