Transfusion transmission of human T-lymphotropic virus type I (HTLV-I) from an asymptomatic blood donor: conservation of LTR U3, env, and tax nucleotide sequences in a recipient with HTLV-I-associated myelopathy

BACKGROUND: Transfusion of human T-lymphotropic virus type I (HTLV-I) contaminated blood is sometimes linked with the rapid onset of HTLV-I- associated myelopathy/tropical spastic paraparesis (HAM/TSP) in immunocompromised recipients. STUDY DESIGN AND METHODS: This study addressed the question of whether HTLV-I variants could emerge in an immunocompromised patient who developed HAM/ TSP after the transfusion of blood from an asymptomatic HTLV-I carrier. Base pairs (n = 2327) of the HTLV-I genome located in the LTR U3 region and parts of the env and tax genes were sequenced and compared to the isolated identified in the asymptomatic blood donor and to well-known ATK-1 and H5 strains. The same analysis was performed on another set of samples from an asymptomatic HTLV-I-positive blood donor and a similar blood recipient. RESULTS: No critical changes in nucleotide sequences were identified in the immunosuppressed HAM/TSP patient when compared with the nucleotide sequences of the corresponding blood donor, the other asymptomatic blood donor and recipient or the ATK-1 and H5 strains. CONCLUSION: Immunosuppression does not seem to favor the emergence of particular nucleotide sequences in the genome located in the LTR U3 region or in parts of the env and tax genes in transfused patients who develop HAM/TSP.