Our RNA interference lentiviral vectors contain siRNAs. We employ a dual convergent promoter system where the sense and antisense strands of the siRNA are expressed by two different promoters rather than in a hairpin loop - to avoid any possible recombination events that can occur. 
   Gentaur guarantees that at least one out of the four siRNA Lentivector constructs purchased in a set will result in over 70% knockdown of gene expression within target cells showing >80% transfection efficiency. If this is not the case, we will provide a one-time replacement of four new constructs with alternative siRNA sequences. To qualify for this replacement, the vectors must be transfected at ≥5 nM and assayed 48 hours post-transfection. Customers must provide adequate data to show >80% transfection efficiency with a positive control, plus additional qPCR data or a western blot to evaluate the level of gene expression. The replacement set will not covered by the same guarantee, and if these constructs are also considered to be ineffective then it is most likely the gene is not susceptible to siRNA knockdown.
   Gentaur limits its obligation and liability for the success of this technology to providing one replacement of any siRNA lentivector product only. Before sending your inquiry, please make sure you have optimized your experiments as far as possible, this includes (where applicable) increasing your MOI and the duration of infection (up to 72 hours), and carrying out clone screening before assaying for knockdown.