Two major subgroups of human T-cell leukemia virus-1 in Japan.

T lymphocytes of patients with human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy (HAM) were cultured. After cultivating for several months, HAM-derived cell lines were tested for the presence of HTLV-1 proviral genome. We have found two major subgroups, the SacI type and the PstI type, of HTLV-1 by the restriction map analysis. They were almost equally distributed among HAM patients. We have also found two types of the provirus in DNA derived from fresh peripheral blood lymphocytes (PBL) or lymph node cells of adult T-cell leukemia/lymphoma (ATL) patients. The PstI type proviruses were predominant in ATL patients. It was concluded that two major subgroups of HTLV-1 exist in Japan and both types have an ability to cause either of two diseases, ATL or HAM.