ERVW-1 and tropical spastic paraparesis: Analysis of HTLV-1 specific antibodies in CSF of HAM/TSP against synthetic peptides of HTLV-1 Gag and Env proteins demonstrated that a diverse intrathecal immune response to several HTLV-1 synthetic peptides, most frequently against Gag p19 (100–130), Env gp21 (458–488), and Env gp46 (175–199 and 288–317) [102, 103].