ERVW-1 and tropical spastic paraparesis: Since strong antibody responses against HTLV-1 antigens have been reported in both serum and CSF of HAM/TSP patients [10,32], we also examined antibody responses for HTLV-1 Gag, Env, Tax and HBZ in both serum and CSF samples of HAM/TSP patients with or without HBZ-specific antibody responses.