Lack of Epstein-Barr virus infection in Chinese myasthenia gravis patients

Abstract

There are three recent contradictory reports on the incidence of Epstein-Barr virus in the pathogenesis of myasthenia gravis, with all studies carried out in Caucasian patients. The current study evaluated whether Epstein-Barr virus infection had a role in the pathogenesis of myasthenia gravis in a cohort of 30 Chinese patients. Serial paraffin sections of thymic hyperplasia obtained from myasthenia gravis patients were analyzed for the presence of Epstein-Barr virus-encoded small RNA -1 and Epstein-Barr virus latent membrane protein 1 by in situ hybridization and immunohistochemistry, respectively. Epstein-Barr virus(+) cervical lymph nodes from lymphoma patients and Epstein-Barr virus(-) thymus specimens obtained during cardiac surgery served as the positive and negative control groups, respectively. All the 30 myasthenia gravis specimens were negative for both Epstein-Barr virus-encoded small RNA -1 and Epstein-Barr virus latent membrane protein 1 tests. However, we obtained well-characterized membrane and cytoplasmic immunohistochemical and in situ hybridization staining for both Epstein-Barr virus latent membrane protein 1 and Epstein-Barr virus-encoded small RNA -1, respectively, in the positive control samples. Our results therefore do not support a role of thymic Epstein-Barr virus infection in myasthenia gravis pathogenesis and calls for an integration of methodological and interpretation issues in detecting Epstein-Barr virus incidence in myasthenia gravis patients.