Schematic representation of the humanization and infection procedure according to Tezuka et al. Human CD133⁺ stem cells purified from HLA-A2-positive cord blood donors are injected into the bone marrow of 7-week-old NOG mice. By 24 to 28 weeks of age, irradiated HTLV-1–producing cells were intraperitoneally injected (IPI) into IBMI-huNOG mice. During the following 7 to 25 weeks, proliferation of CD25⁺CD4⁺ T cells and ATL-like features were observed in infected mice. Interestingly, these infected mice developed cytotoxic T lymphocytes as well as antibodies against HTLV-1 antigens.