CTRL and Immunodeficiency: Also, when we injected bdLV.CTRL in neonatal NOD/SCID mice, which have a severe combined immunodeficiency affecting T- and B-lymphocyte development, we still observed a consistent ≈30% decrease in the percentage of GFP+ cells within the first 3 weeks of age (6.2 ± 0.9, 4.4 ± 0.3 and 4.2 ± 0.8% of GFP+ cells at PND10, PND21 and PND40, respectively; mean ± SEM, n = 3–4 mice/group; Fig. 2J).