ERVW-1 and myeloid sarcoma: Env-antigen expression is again confirmed to occur in MS lesions, particularly within infiltrated perivascular macrophages, which is also consistent with previous observations of cultured macrophages, isolated from MS blood.3,6 These results thereby support the parallel between early results showing retroviral expression in MS1,3,17,53 and this pathogenic HERV-W expression of MSRV subtype sequences and Env.