Intrathecal synthesis of Epstein-Barr virus antibodies 15 years before onset of multiple sclerosis Guerrero Fernández, Manuel Miguel Serrano Álvarez, Carmen Fonronda Bengoa, Jesús Barrero Hernández, Francisco Javier Sorlozano Puerto, Antonio Multiple sclerosis Epstein-Barr virus Intrathecal antibody synthesis A 48-year-old woman was diagnosed with multiple sclerosis (MS) in 2019. She participated with blood and cerebrospinal fluid samples as a spinal anaesthesia surgery patient for a case–control study on viruses and MS in 2003. The study had already demonstrated intrathecal antibody synthesis (ITS) to Epstein-Barr virus (EBV) but not against measles, rubella and varicella-zoster (MRZ) reaction viruses in this individual at the time of recruitment. A 2025 study review established that she was the only patient in her control subgroup who also developed MS. This case shows that a specific EBV-ITS may be an early indicator of a ‘biologically isolated syndrome’ in MS. 2026-03-20T09:20:59Z 2026-03-20T09:20:59Z 2026-03-17 journal article Guerrero-Fernández MM, Serrano-Álvarez C, Foronda-Bengoa J, Barrero-Hernández FJ, Sorlózano-Puerto A. (2026). Intrathecal synthesis of Epstein-Barr virus antibodies 15 years before onset of multiple sclerosis. Mult Scler. 17:13524585261427398. doi: 10.1177/13524585261427398 https://hdl.handle.net/10481/112333 10.1177/13524585261427398 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Attribution-NonCommercial-NoDerivatives 4.0 Internacional Sage Journals