High ratio of HTLV-1-infected cells in HTLV-1 associated myelopathy (HAM).

Sixteen patients with HTLV-1 associated myelopathy (HAM) were examined for the presence of HTLV-1 provirus genome by Southern blot analysis of genomic DNA from peripheral blood mononuclear (PBM) cells. Random integration of the provirus was detected in 14 of 16 HAM patients. By contrast, the provirus genome could not be detected in 6 non-HAM HTLV-1 carriers, HAM patients were found to have significantly higher antibody titer to HTLV-1 in the sera compared with carriers. These features of HAM patients, i.e., detectable levels of provirus integration in PBM cells and high antibody titer to HTLV-1 in the sera, were noted in 2 wives of HAM patients with neurological signs and abnormalities. High anti-HTLV-1 antibody titer and detection of the provirus genome by Southern hybridizations may be useful for screening subclinical HAM cases and elucidating pathogenesis.