Lentiviral particles overview

We have partnered with Flash Therapeutics to provide ready-made lentiviral particles for use in research applications involving tet-inducible expression or fluorescent reporters. We believe these are the highest-quality ready-made lentiviral particles available due to Flash Therapeutics' unique method of producing high-purity, high-titer particles with superior performance.

What you can expect with lentiviral particles from Flash Therapeutics:

• 100% transduction of many primary cells (including neurons, endothelial cells, and stem cells)
• High expression in primary cells when delivered at a high MOI
• No cytotoxic effects
• Functional titer—not just a particle count

What is different about lentiviral particles produced by Flash Therapeutics and sold by us?

Unlike ready-to-use lentiviral particles from other suppliers, the particles in our catalog are produced via a multi-step purification process which results in very high titers and high purity. The high titer increases transduction efficiency, and the high purity reduces cytotoxicity, so you can successfully transduce a large number of different cell types, including primary, immortalized, adherent, and suspension cells, and retain high cell viability.

State-of-the-art lentivirus production platform

Flash Therapeutics has developed a unique process for the production of high-titer viral supernatant. This process involves generation of virus in 293T cells in a serum-free medium, followed by back-to-back tangential ultrafiltration with diafiltration to concentrate and purify the particles. Finally, after titration and assaying for RCL, safe, high-titer, high-purity lentiviral vectors are ready for transduction of your cells.

Figure 1. Overview of the process for generating high-titer lentiviral particles. Through this proprietary, large-scale process Flash Therapeutics is able to produce very high-titer, high-purity lentiviruses ready for transduction of many different cell types.

We supply a functional titer, not simply a particle count

Not all advertised titers are the same! Most vendors of ready-made viral particles determine their titers using a simple particle count. This count will include free capsid protein, nonfunctional and immature virions, as well as functional virus. For every lot of our lentiviral particles, we provide a functional titer of >1 x 10⁹ transduction units per ml (TU/ml). The functional titer is not just the total particle number; it is a measurement of the total number of virions capable of integrating into cells. Compared to the titration methods of other vendors, Flash Therapeutics' method ensures an accurate count of functional particles. In real terms, this means our viral preps contain up to 100-fold more infectious particles than preps from other vendors.

Why are titer and purity important?

Higher titers increase the speed, ease, and efficiency of lentiviral transductions. Higher lentiviral titers allow you efficiently infect even hard-to-transduce cell types at a lower MOI. The high purity of the lentiviral particles dramatically reduces cytotoxicity further increasing the efficiency of transduction of delicate cells.

Why serum-free medium?

Production in serum-free medium greatly improves the quality of the lentivirus as a vector for gene delivery: eliminating serum from the lentiviral supernatant reduces the levels of contaminating proteins that need to be removed in the purification process. This allows for increased titer (TU/ml), decreased physical particles to transducing units ratio (PP/TU; more effective particles than ineffective particles), and increased transduction efficiency of the virus prep. The Flash Therapeutics particles display higher purity than those concentrated by classic ultracentrifugation methods—even when the Flash Therapeutics particles are loaded at a 10-fold higher concentration.

Products available from Takara Bio

Viral particles for Tet-inducible gene expression

We offer ready-made lentiviral particles to introduce constitutive expression of the Tet-On 3G transactivator in your cells of choice. In the presence of doxycycline (a tetracycline derivative), the Tet-On 3G transactivator binds to and activates transcription of, the P_TRE3G promoter. This allows you to precisely control transcription of any gene cloned downstream of P_TRE3G. Learn more »

Viral particles for subcellular localization studies

Constitutive lentiviral reporter vectors are prepackaged lentiviral particles that deliver fluorescent proteins targeted to specific organelles or subcellular structures. These particles can be used to create reporter cell lines for the study of cytoskeletal and organelle structure and function in living cells or protein localization studies. Learn more »

Schematic maps of expression plasmids used for preparation of pre-packaged, high concentration lentivirus particles. Click on the images to view larger versions.