FIG. 1.

Biotin-dependent capture of 293T-derived lentiviral vectors. For LV.bla vector supernatants from 293T (VSV-G) and 293T-Ampho (amphotropic, stable transfection of the murine leukemia virus 4070A amphotropic envelope-encoding pALF [13] into 293T) cells without (C) and with (B) biotinylation, titers were immediately determined on K562 cells in 4 μg/ml Polybrene. Alternatively, the vectors were captured and magnetically concentrated 100-fold with streptavidin-PMP prior to titration (C conc and B conc). The remaining supernatant following removal of the PMP (B Dep) was also used to infect target cells as an estimate of the efficiency of capture.