In this model, rats inoculated with ILT-M1, an IL-2-dependent HTLV-1-infected T cell line derived from an HAM/TSP patient, transmitted HTLV-1 to their offspring at a high rate (50–100%), and the rate of transmission correlated with the PVL of the infected mother rats [131]. The gene discussed is IL2; the disease is tropical spastic paraparesis.