CD8A and Epstein-Barr virus infection: Virus-specific CD8+ T cell responses play an essential role in the control of EBV infection [45] and have been investigated in previous studies in MS using mainly IFN-γ ELISPOT analysis in PBMCs stimulated in vitro with EBV+ lymphoblastoid cells [20], [22], viral lysates [21], individual [19] or pooled [21] EBV lytic and latent peptides, and more recently using MHC-peptide tetramer staining [23].