IL2RA and severe combined immunodeficiency: In the first set of experiments, we extended the studies to determine the clearance rate of cda1∆2∆3∆ at a vaccination dose of 1 × 107 colony-forming unit (CFU) for CBA/J, BALB/c, C57BL/6, and non-obese diabetic, severe combined immunodeficiency, IL-2R common gamma-chain deficient (NSG) mice.