Retroviral and Lentiviral Transduction Protocol

Retrovirus production was performed as described previously^{11 (link)}. Briefly, transfections of the retroviral constructs together with pHIT60 (gag-pol) and pHIT123 (env) were performed using Lipofectamine 2000 (Invitrogen). 10 mM sodium butyrate was used for induction. The virus supernatant was collected, filtered through a 0.45 μm filter. For lentivirus, PCD/NL-BH (gag-pol) and pMN-VSV-G (env) were used for virus packaging. The lentivirus was concentrated by centricon centrifugal filters from EMD Millipore (Billerica, MA). For transduction, non-tissue culture treated 6-well plates were coated with 50 μg/ml retronectin (Takara, Madison, WI), and virus was loaded by centrifugation (2000 × g, 90 min at 32 °C). Then virus was discarded and 2 × 10⁶ pre-B cells were transduced per well by centrifugation at 600 × g for 30 minutes. Details of retroviral and lentiviral vectors used were provided in Supplementary Table 5.