Intriguingly, it turned out that anti-HERV-W Env mAb 6A2B2 (detecting an antigen in MS brain lesions, see above) was raised against a 379 amino acid sequence encoded by MSRV env clone AF127228, which, except for two C-terminal amino acid exchanges, is identical to the Xq22.3 HERV-W Env amino acid sequence [11,24]. This evidence concerns the gene ERVW-1 and myeloid sarcoma.