As control, HTLV-I-specific antibodies to Gag, Env and Tax were also able to be detected in memory B cell pools of both HAM/TSP patients with and without HBZ-specific antibody response, but HBZ-specific antibody production was not detected in the memory B cell cultures of HAM/TSP patients without HBZ-specific antibody response (data not shown). This evidence concerns the gene ERVW-1 and tropical spastic paraparesis.