1. Background and purpose of the procedure
Lentiviral transduction is an effective method for creating a stable cell line with a DNA cassette of interest integrated into its genomic DNA. The second-generation system has one packaging plasmid which includes all the important packaging components: Gag, Pol, Rev, and Tat. To produce virus, it requires a single packaging plasmid, an envelope plasmid, and a transfer vector (i.e., with the gene of interest to be expressed).
2. Materials and equipment
- HEK293T cells (ATCC, CRL-3216)
- Complete cell culture medium (DMEM, Gibco11995073) with FBS (FB Essence, VWR, 10803-034) and antibiotics (Penicillin/Streptomycin, Corning, 30-002-CI)
- D-PBS, without Ca++ and Mg++ (Gibco, 14190144)
- Opti-MEM Serum-free media (Gibco, 11995)
- Lentiviral packaging vector psPAX2 (Addgene, 12260)
- VSV-G envelope vector pMD2.G (Addgene, 12259)
- pLV transfer vector containing the gene of interest
- T75 TC-treated Flask
- 15 mL and 50 mL polypropylene tubes
- Cell counter/Hemacytometer
3. Method
Day 1
- For each plasmid to be transfected, plate 3 x 106 HEK293T cells in 10-15 mL of media in a T75 TC-treated flask
- Incubate the cells at 37˚C, 5% CO2 overnight
Day 2
- Perform the transfection in the late afternoon, transfection mix should only be incubated with the cells for 8 – 12h maximum
- In a 1.5 mL microcentrifuge tube, mix:
- 1 mL of Opti-MEM
- 10 µg of transfer vector (pLV)
- 10 µg of packaging vector (psPAX2)
- 5 µg of envelope vector (pMD2.G)
- 75 µL of Lipofectamine reagent (3 µL:1 µg of DNA) [yellow cap tube]
- 50 µL of Lipofectamine 3000 (2 µL:1 µg of DNA) [red cap tube]
- Vortex for 10 sec
- Incubate the mix for 15-30 min at room temperature
- Gently add the DNA:Lipofectamine 3000 mix to the cells being careful to not detach the cells from the flask
- Swirl the flask gently to disperse the mixture evenly
- Incubate the cells for 15-18 h at 37˚C, 5% CO2
Day 3
- In the morning, change the media to remove the transfection reagent. Replace with 20 mL of fresh complete DMEM. Be careful to not detach the cells from the flask
- Incubate the cells for 48 h at 37˚C, 5% CO2
Day 5
- Harvest media containing the lentiviral particles and transfer to a 50 mL polypropylene tube
- Spin media at 1,500 rpm for 5 min any cells or cells debris that were collected during harvesting
- Viruses may be stored at 4˚C for short-term storage (1 day to 1 week) or frozen at -80˚C for long term-storage (up to 1 year, aliquots into smaller tubes to minimize freeze/thaw cycles)
- Add 10 mL of fresh complete DMEM. Be careful to not detach the cells from the flask [optional]
- Incubate the cells for 48 h at 37˚C, 5% CO2 [optional]
Day 6
- Harvest media containing the lentiviral particles and transfer to a 15 mL polypropylene tube
- Spin media at 1,500 rpm for 5 min any cells or cells debris that were collected during harvesting
- Viruses may be combined with the viruses harvested on Day 5 and stored at 4˚C for short-term storage (1 day to 1 week) or frozen at -80˚C for long term-storage (up to 1 year, aliquots into smaller tubes to minimize freeze/thaw cycles)
4. References
Chu C, Xin A, Zhou Y, Zhang Y. A simple protocol for producing high-titer lentivirus. Acta Biochim Biophys Sin (Shanghai). 2013 Dec;45(12):1079-82. doi: 10.1093/abbs/gmt112. Epub 2013 Oct 10. PMID: 24113089.
Producing lentivirus in HEK293T cells using a 2nd Generation lentiviral system, from David P. Turner, Medical University of South Carolina, Hollings Cancer Center