We also demonstrated that the transcription levels of HERV-H and HERV-K (HML-6) Env genes in ATLL-derived cells and Peripheral Blood Mononuclear Cells (PBMCs) from acute ATLL patients were significantly higher than those in HTLV-1 asymptomatic carriers, showing that the occurrence of ATLL can be associated with the expression of these HERV genes, further supporting that antibodies against HERV Env proteins may be potential biomarkers for the earliest diagnosis of ATLL. Here, ERVW-1 is linked to adult T-cell leukemia/lymphoma.