ERVW-1 and myeloid sarcoma: Human herpesvirus 6 (HHV-6) infection has long been suspected of playing a role in the pathogenesis of multiple sclerosis (MS) and neuroinflammation, and recently it has been demonstrated that HHV-6A induces the expression of HERV-W/MSRV Env protein that in turn may play a role in the inflammatory process [66].