DETECTION OF HUMAN T-LYMPHOTROPHIC VIRUS TYPE-I (HTLV-I) PROVIRAL DNAAND ANALYSIS OF T-CELL RECEPTOR V-BETA CDR3 SEQUENCES IN SPINAL-CORD LESIONS OF HTLV-I-ASSOCIATED MYELOPATHY TROPICAL SPASTIC PARAPARESIS/

Identification of the localization of human T lymphotrophic virus type I (HTLV-I) proviral DNA in the central nervous system (CNS) is crucia l to the understanding of the pathogenesis of HTLV-I-associated myelop athy (HAM)/tropical spastic paraparesis (TSP) pathogenesis. We have de veloped a sensitive detection method, called two-step polymerase chain reaction (PCR) in situ hybridization, which enabled us to detect the HTLV-I proviral DNA in paraffin-embedded spinal cord tissue sections f rom HAM/TSP patients. HTLV-I proviral DNA was detected only in the nuc leus of lymphocytes that had infiltrated into the spinal cord. However , no proviral DNA was amplified in any neuronal cells, including neuro ns and glial cells. This indicates that the demyelination of the spina l cord by HTLV-I as a result of viral infection of oligodendrocytes or neuronal cells is unlikely. The T cell receptor VP gene sequence from lymphocytes in the spinal cord lesions taken from the same HAM/TSP au topsy cases revealed unique and restricted CDR3 motifs, CASSLXG(G) (on e-letter amino acid. X is any amino acid), CASSPT(G), and CASSGRL whic h are similar to those described in T cells from brain lesions of mult iple sclerosis (MS) and in a rat T cell clone derived from experimenta l allergic encephalomyelitis (EAE) lesions. The present results sugges t that T cells containing restricted V beta CDR3 motifs, which are als o found in MS and EAE, become activated upon HTLV-I infection and infi ltrate into the spinal cord lesions of HAM/TSP patients.