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Search for endogenous EBV infection in the intrathecal compartment of MS patients


Joelle Dorskind, Alan Salgado, Peter Kosa, Bibiana Bielekova

Neuroimmunological Diseases Unit, Neuroimmunology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD

Multiple sclerosis (MS) is the most common demyelinating disease. A number of studies linked the Epstein-Barr virus (EBV) infection with MS. However the mechanism(s) how EBV infection enhances susceptibility for MS remains unclear. A specific hypothesis, that remains highly controversial, stipulates that intrathecal EBV infection may contribute to formation of tertiary lymphoid follicles in the meninges of MS patients, thus sustaining intrathecal inflammation. Sequencing of the EBV genome showed a genetic polymorphism affecting the EBNA-2 gene, which can be categorized as type I and II. It has been shown that in MS patients, the rate of co-infection by EBV types I and II in peripheral blood mononuclear cells are significantly higher compared to controls (Santon et al., 2011). We decided to use this information to help us answer the question of intrathecal EBV infection in MS. Specifically, we designed a protocol for expansion and immortalization of B cells in the cerebrospinal fluid (CSF) using EBV type I virus. If these CSF B cell lines (BCL) contain EBNA-2 DNA specific for EBV type II virus, this has to reflect endogenous intrathecal EBV infection. The goal of this study was to determine endogenous EBV type II infection in intrathecal BCL. Peripheral immortalized B cells were used as controls and EBV genotypes in MS subjects were compared to other inflammatory and noninflammatory neurological diseases controls. We confirmed the presence of EBV type I genome in immortalized peripheral and intrathecal B cell lines. However, no double positive cell lines were identified. Generation of a new type II specific primer enabled us to amplify EBNA-2 type II PCR product in the presence of EBV type I DNA, resulting in identification of three intrathecal and one peripheral B cell line positive for EBNA-2 type II. This result would indicate an endogenous intrathecal EBV type II infection in some MS subjects. Sequencing of the PCR products will be performed in order to confirm these results.

Last updated December 14, 2012