Transduction efficiency of BM cells in vitro by lentiviral vectors expressing GalT. (A) Specific integration in the genome assessed by PCR at 5 days after transduction. Genomic DNA was isolated from GalT and REV-transduced cells. Gene-specific primers were used to demonstrate the presence of the GalT and REV genes in transduced cells. The electrophoresis results from representative data are shown. – indicates not transduced, +; transduced. (B) Surface expression of αGal on transduced cells as assessed by flow cytometry using lectin-IB4 to identify αGal⁺ cells. The boldface line indicates nontransduced bone marrow; the thin line, GalT-transduced bone marrow.