Importantly, the cumulatively higher number of HBZ- and Tax-1-expressing cells in HAM/TSP patients compared to HTLV-1-infected AC strongly suggests that evolution toward the neuroinflammatory disease modifies only the number of HBZ- and Tax-1-positive cells but not the HBZ- or the Tax-1-specific intracellular localization. Here, HBZ is linked to tropical spastic paraparesis.