ERVW-1 and myeloid sarcoma: Further linking this HERV-W expression with MS, successive studies have evidenced that MSRV env protein was found in the serum of 73% of MS patients and not in controls [1] and MSRV/HERV-W pol and env RNAs were significantly elevated in autopsied brain tissue and peripheral blood mononuclear cells (PBMCs) from MS patients versus controls [17], [18].