TCR transfer results in the formation of chimeric TCRs. Sorted AV2BV2 and AV18BV13 CMV-specific T cells (> 98% pure) were transduced with the HA-2–AV15-GFP and the HA-2–BV18-NGFR retroviral vectors. Seven days after transduction, the single- and double-transduced subsets were gated on bases of marker gene expression (A), the HA-2–AV15 single-positive cells were gated on bases of GFP⁺NGFR⁻ (gate 1), the HA-2–BV18 single-positive cells were gated on bases of GFP⁻NGFR⁺ (gate 2) and HA-2–AV18BV13 double-positive cells were gated on bases of GFP⁺NGFR⁺ (gate 3). Cells were analyzed for CMV-TCR expression using CMV^A2 tetramers (B) and mAbs directed against the CMV-TCR β-chains BV2 or BV13 (C); in addition, total TCRαβ cell-surface expression was measured (D). In the figures the MFI of the staining is indicated as the percentage of control-transduced cells (100%) of 2 independent experiments. Error bars indicate SD.