Figure 1.

Self-inactivating (SIN) γ-globin lentiviral vectors demonstrate efficient gene transfer into murine sickle cell hematopoietic stem cells (HSCs). (a) Schematic representation of the integrated γ-globin lentiviral vector proviral form. Shown at top is the vector backbone which contains the central polypurine track (cPPT) and the rev responsive element (RRE) and has a SIN design in which the promoter and enhancer of the HIV U3 region have been deleted. Shown below are the V5 and V5m3 globin expression cassettes which are identical with the exception of the 3′-untranslated region (3′-UTR) (hatched rectangle and speckled rectangle). Both vectors contain the same composite 3.1 kb of transcriptional regulatory sequences from the β-globin locus control region with contributions, as indicated, from HS4, HS3, and HS2 (open rectangles). The filled arrowhead represents the 130-bp β-globin promoter while the γ-globin exons are indicated by hatched arrowheads. (b) Bone marrow (BM) vector copy numbers of individual mice transplanted with sickle cell HSCs transduced with the V5 and V5m3 vectors. Four to five months post-transplant, copy numbers were determined by Southern blot analysis of BM DNA from transplanted animals, relative to a cell line known to contain a single proviral copy.