In the present study, we evaluated the ex vivo and in vitro effects of AA and IFN-α treatment on peripheral blood mononuclear cells (PBMCs) of seronegative normal donors, HTLV-1-infected asymptomatic carriers and HAM/TSP patients and HTLV-1-infected cell lines, respectively. The gene discussed is IFNA2; the disease is tropical spastic paraparesis.