( Retroviral-mediated Delivery of siRNA ...)Enhanced siRNA Delivery and Long-term Gene Silencing

The pSilencer 5.1 Retro System enables researchers to study the long-term effects of reducing the expression of specific genes in cell culture models. These retroviral vectors make use of H1 or U6 Polymerase III promoters to stably express siRNAs, even in difficult-to-transfect cell types. This technology expands RNA interference research to address long-term alteration of the expression of genes that cause disease phenotypes.

Introduction: Getting siRNAs into Cells with Viruses
The use of siRNAs to induce gene silencing has enormous potential for identifying and understanding gene function and may eventually be used as a therapeutic strategy. Approaches to produce siRNA molecules include chemical synthesis, enzymatic synthesis, and DNA-based expression vectors. In general, production of siRNA in vitro by chemical synthesis is preferred for most transient experiments. However, DNA-based approaches have distinct advantages when performing long-term RNAi studies or when conducting studies in cells or organisms into which siRNAs are particularly difficult to deliver.

The DNA-mediated siRNA expression techniques can be divided into viral and nonviral methods. Both involve the expression of a short hairpin RNA transcript that is processed endogenously to an siRNA. Although the nonviral mediated approach is effective for transient RNA interference
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