High-efficiency transduction of myeloid and lymphoid leukemic cells with the DISC-HSV β-GAL vector. The x-axis denotes the intensity of β-GAL staining 48 hours after transduction with the DISC-HSV vector at various pfu/cell. Blast cell populations are defined by appropriate gating using forward-versus-side scatter. Representative results of one AML and one ALL patient are shown from the patients presented in Table 1. *pfu/cell:- for details of titering see Materials and Methods.