In this context, if infiltrating cells infected with HTLV-1 express low levels of viral antigens, Tax 301–309-specific CTLs restricted to HLA-A*24 may recognize the antigens more efficiently than Tax 11–19-specific CTLs restricted to HLA-A*02, resulting in stronger inflammation and leading to the immunopathology of HAM/TSP. The gene discussed is HLA-A; the disease is tropical spastic paraparesis.