With the combined effects of sEV, Epstein–Barr nuclear antigen 1(EBNA1)–DNA complexes, EBNA1–IgG–complement immune complexes, HERV-W/K sAg elements, and the early reactivation induced by other herpesvirus infections, the inflammatory cascade continuously amplifies, ultimately resulting in MS onset. Here, SAG is linked to Herpesviridae infectious disease.