Although the relative contribution of the above mentioned costimulatory and coinhibitory factors to the observed dysregulation of chronically activated HTLV-1-specific CD8+ T cells in HAM/TSP patients remains to be determined, restoration or modulation of virus-specific CD8+ T cells in HAM/TSP patients may be important to prevent further tissue damage in the CNS and progression of HAM/TSP. This evidence concerns the gene CD8A and tropical spastic paraparesis.