Presence of HTLV-I Tax protein in cerebrospinal fluid from HAM/TSP patients

Infection with human T-cell lymphotropic virus type I (HTLV-I) have been associated with the development of the HTLV-I-associated myelopathy/Tropical Spastic Paraparesis (HAM/TSP). The disease affects the pyramidal tract at the distal segments of spinal cord, generating a spastic paraparesis. We studied the presence of Tax protein in cerebrospinal fluid cells and spinal fluid (CSF) of 35 Chilean patients: 22 HAM/TSP patients (15 HTLV-I-seropositives, and 7 seronegatives), and 13 controls (9 PSP and 4 CJD non-infected patients). Tax antigens were evaluated with monoclonal antibodies reacting with Tax by immunofluorescence and ELISA assays in cerebrospinal fluid cells and CSF, respectively. Proviral was evaluated by PCR of tax gene in cerebrospinal fluid cells. Tax antigen was detected in CSF and lymphocytes of CSF from 4 and 12 HAM/TSP patients, respectively. Lymphocytes of CSF of 8 HAM/TSP (6 seropositives and 2 seronegatives) showed the presence of tax gene. These results show that cells of CSF from HAM/TSP patients are able to express and export Tax protein towards the CSF. This is the first report of the presence of Tax protein in cerebrospinal fluid cells and CSF from HAM/TSP HTLV-I seronegative patients.