 Premade inducible lentiviral particles can be used for transient or stable gene expression in dividing and non-dividing cells without using any transfection reagents. Gentarget provide premade particles generated from two types of lentivecors, the SureTiter lentiviral system and this Tet induction lentiviral system.
What is Gentarget's inducible expression lentiviral particles? 
Constitutive expression of some human gene may be toxic or unwanted. Therefore, a controlled expression is desirable. Gentarget generated inducible ready-to-use lentiviral particles to satisfy this need. Those particles contains sequence fully verified genes, expressed under a tetracycline regulated suCMV promoter in which two copies of tetracycline (tet) operator sequences was integrated (see the lentivector map scheme above). In the presence of a repressor protein [the tetracycline regulator (tetR)], the transcription of suCMV was repressed by the binding of tetR to the tet operator sequences. Once the tet or Doxycycline (Dox), a derivative of tetracycline is added, the tetR protein switch binding to tet and released from promoter, and the transcription started (see the induction mechanism figure below).
 How to deliver the repressor regulator for inducible expression? The repressor protein (tetR) must be pre-existence in order to use those particles as tet induction system. The presence of tetR can be achieved by the following methods: - Particles are used in a tetR expression stable cell line that constantly express tetR protein;
- Transfect a tetR expression plasmid before transduce lentiviral particles;
- Co-transduce both the tetR repressor particles and the gene expression virus into the sample cell line (applied with equal MOI);
How much tetracycline used for induction and how many fold induction? Tetracycline regulator has low basal and very high induction folds. The expression is induced in the presence of Tetracycline or Doxycycline (Dox), a derivative of tetracycline. The amount of tetracycline to use is dependent upon cell types, a common used final concentration is 1ug/ml. Please be advised that many bovine sera used in culture are contaminated with tetracycline or its derivatives which can affect basal expression. Depend upon the cell lines and the repressor protein expression levels, normally a 20-fold to 1000-fold can be obtained after the induction. The following picture demonstrated the GFP expression from premade inducible GFP lentiviral particles (Cat#: LVP024) before and after induction. 
Please see our premade particles production page for inducible human gene expression. References: - Annu Rev Microbiol. 1994;48:345-69.
- Microbiol Mol Biol Rev. 2005 Jun;69(2):326-56.
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Expression lentiviral particles->
