/Products/Delivery and Packaging/Retro-X™ Universal Packaging System and Concentrator/Product Overview
The Retro-X™ Universal Packaging System and Retro-X™ Concentrator from Clontech has been validated for high titer virus production with shERWOOD-UltramiR Retroviral shRNA constructs (LMN).  The system provides the GP2-293 packaging cell line optimized for retroviral production and all four commonly used envelopes including VSV-G, eco, ampho and 10A1.  The choice of envelopes provides the broadest range of cell types allowing allow you to choose the tropism that is most appropriate for your RNAi experiment.  Combined with the Retro-X™ concentrator these tools enable easy shRNA-mir delivery with quick access to high titer virus. 

  • Validated 48 hour protocol for high titer MLP retroviral shRNA-mir expressing viral particles 
  • Consistent titers at greater than 106 with VSV-G
  • Easily concentrate up to 10^8 with Retro-X Concentrator
  • All commonly used envelopes for RNAi applications across a large range of cell types

Schematic for retroviral packaging using Retro-X Universal Packaging System. The system consists of the GP2-293 Packaging Cell Line, which expresses viral Gag and Pol proteins, and a set of 4 viral env expression vectors. Cotransfecting an env vector with your retroviral construct allows you to select the ideal tropism for your virus.

Package virus in 48 hours

How the Universal Packaging System Works
The GP2-293 cell line included in the Retro-X Universal Packaging System contains the MMLV gag and pol genes stably integrated in its genome. These two proteins are necessary for viral replication and particle formation, and their stable expression in the GP2-293 cell line contributes to high viral titers (Figure 1). The remaining component of the packaging process, a viral envelope gene, is supplied transiently and expressed to high levels when it is cotransfected with a user-supplied retroviral expression vector bearing the gene of interest.  The co-transfected env gene encodes the viral envelope protein (Env) that determines the host range (tropism) of the virus, while high levels of Env help support the production of high titer supernatants.

Schematic showing simple concentration protocol. Add Retro-X Concentrator reagent to clarified viral supernatant, incubate overnight at 4°C, and spin.

Concentrate MLP shRNA-mir expressing viral particles without ultracentrifugation

Retro-X Concentrator provides a fast, simple, and highly efficient method for concentrating MLP retroviral shRNA-mir viral particles.  Just mix the retroviral supernatant with the Retro-X concentrator, incubate for a short period, and spin the mixture in a standard centrifuge. 

  • Simple mix and spin protocol
  • Easily scaled up for larger volumes
  • No ultracentrifugation required
  • Up to 100X concentration with 90% recovery