We transduced rhesus CD34+ cells with the optimized reverse-oriented vector and forward-oriented vector including a GFP or enhanced yellow fluorescent protein (YFP) gene at a multiplicity of infection (MOI) 50 in a competitive repopulation assay following 10 Gy total body irradiation (Fig. 2a and Supplementary Fig. 5B). Here, CD34 is linked to infection.