ERVW-1 and myeloid sarcoma: Now, using their newly constructed PCR assay, Mameli and colleagues were able to compare and contrast the expressions of HERV-W generic env, MRSV env and ERVWE1 env (syncytin-1) expression in the plasma, in cultured PBMCs and in the supernatant of the cultured cells, in four MS patients who had not yet been treated, in four MS patients who had been treated and in six healthy blood donors acting as controls.