CD8A and Epstein-Barr virus infection: Collectively, muscle fatigue is a common clinical manifestation of EBV infection and reactivation and there exist multiple potential molecular pathways that may underlie clinical symptoms including the infiltration of peripheral EBV-infected CD4+ T cells followed by reactive microgliosis, oligodendroglial demyelination, the direct infiltration of CD8 + T cells and the subsequent cytotoxic response that might cause the weakness in in skeletal muscle tissues (Fig. 3).