Southern blot analysis of MSCV-m91Neo integration in long-term reconstituted transplant recipients. Genomic DNA from wild-type (WT) and X-CGD control mice was obtained from bone marrow (BM), spleen (S), and thymus (T) for X-CGD mice 11 months posttransplantation with MSCV-m91–transduced BM. Ten micrograms of DNA was digested with either Kpn I (A) or EcoRI (B), and after agarose gel electrophoresis, Southern blots were prepared and probed with radiolabeled neomycin phosphotransferase cDNA. The band derived from a Neo gene in the X-CGD mice (present in the endogenous gp91^phox gene as a result of homologous recombination20) is marked by an arrow on the left. Sizes of molecular weight markers are as indicated. Data is representative of seven mice analyzed at ≥10 months posttransplantation with MSCV-m91Neo–transduced BM. (A) DNA was digested with Kpn I, which cleaves within the 5′ and 3′ LTR of the approximately 4.5-kb MSCV-m91Neo provirus. (B) DNA was digested with EcoRI, which cleaves at a single site in MSCV-m91Neo just 5′ to the murine gp91^phox cDNA. Asterisks and dots indicate junctional fragments detected in bone marrow DNA samples, at least one of which was also detected in multiple hematopoietic tissues.