Detection of HTLV-I in Peripheral Blood Lymphocytes from Patients with Chronic HTLV-I-Associated Myelopathy/Tropical Spastic Paraparesis and Asymptomatic Carriers by PCR-in Situ Hybridization

Less than 5% of people infectcd with human T-lymphotropic virus type I (HTLV-I) develop HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic progressive neurologic disease. A number offactors have bcen implicated in the development ofHAM/TSP including heterogeneity of viral sequences, host-genctic background, viral-specific cellular immune responses and viral load. This study examined the presence of HTLV-1 tax DNA in peripheral blood lymphocytes (PBL) from 2 chronic HAM/TSP patients and 2 asymptomatic HTLV-I carriers by using PCR-in situ hybridization (PCR-ISH) for the in situ presence ofproviral HTLV-I tax DNA. By this technique, rare PBL from thesc HTLV-I-infected individuals contained HTLV-1 DNA. PCR-ISH did not detect any difference in the number of infected cells between HAM/TSP patients and asymptomatic carriers.