The presence of HTLV-I proviral DNA in the central nervous system of patients with HTLV-I-associated myelopathy/tropical spastic paraparesis

Human T-lymphotropic virus type 1 (HTLV-I) is a pathogenic retrovirus associated with a chronic progressive myelopathy, termed HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP), as well as adult T-cell leukemia (ATL). A chronic inflammatory process has been implicated in HAM/TSP by a pathological study, but the exact mechanism still remains unknown. To understand better the complex mechanism of disease induction by HTLV-I, I studied the spreading pattern of HTLV-I in both peripheral blood mononuclear cells (PBMNCs) and central nervous system (CNS) tissues in patients with HAM/TSP using a quantitative polymerase chain reaction (PCR) method. My results indicated the primary event to be the efficient replication of HTLV-I in vivo, whereas HTLV-I is likely to be present in the constituent cells of the CNS in addition to the infiltrating mononuclear cells.