Competitive injection of SCID-X1 dogs with EF1α and PGK FV vectors. (A) Dogs R2258 and R2260 were injected with a combination of FV vectors PGK.γC.FV and EF1α.γC.FV containing the fluorophores eGFP or mCherry. (B) Kinetics of lymphocyte reconstitution (lymphocytes per microliter of peripheral blood) in R2258 and R2260. Range of lymphocyte counts in healthy dogs is shown by horizontal dashed lines. (C) Long-term analysis of gene marking in peripheral blood lymphocytes from R2258 and R2260 for the PGK and EF1α FV vectors based on fluorophore expression. Lymphocyte population was defined based on forward and side scatter. T2A, thosea asigna virus 2A self-cleaving peptide.