Since many neurological diseases caused by viruses, including HAM, involve the infiltration of CD8+ CTLs into the CNS, it is possible that EVPs originating from activated CD8+ T-cells may play important functional roles in the neural proinflammatory response, both through antigen presentation and activation of other immune cell types, and/or by inducing inflammation, cytokine production, and cell death in neural lineage cells. This evidence concerns the gene CD8A and tropical spastic paraparesis.