Myelin oligodendrocyte glycoprotein antibody-associated disease presenting as encephalitis and concurrent Epstein-Barr virus detection: a case series.

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an autoimmune disorder affecting the central nervous system (CNS), characterized by the presence of autoantibodies against MOG (MOG-IgG) in serum or cerebrospinal fluid (CSF). While Epstein-Barr virus (EBV) is implicated in multiple sclerosis (MS), its role in MOGAD remains unclear. Here, we report five cases of newly diagnosed MOGAD manifesting as encephalitis, in whom concurrent EBV-related laboratory findings were detected. All patients tested positive for serum MOG-IgG by live cell-based assay (CBA). Regarding therapeutic response, three patients exhibited transient improvement in CSF parameters following initial antiviral therapy. However, clinical recovery was observed only after administration of corticosteroids (either high- or low-dose). In refractory cases, additional interventions with intravenous immunoglobulin (IVIG) or tocilizumab were applied. In conclusion, this case series suggests that EBV-associated immune activation may coexist with some MOGAD patients presenting as encephalitis, which requires validation in larger prospective and mechanistic studies in the future.