WARF TECHNOLOGIES

In vivo phage display is a protein library development and screening tool that has proven to be a powerful means of identifying new peptide ligands for specific targeting of organs by drugs and gene therapy vectors.  This display system works by incorporating protein libraries into the genome of a bacteriophage, a virus that only infects bacteria.  The proteins are incorporated into the coat protein of the virus.  Upon expression of the fusion proteins, the phage displays one member of the protein library on its surface.  The phage library then can be screened for interaction of the protein library with a selection target. 

Although commercially available systems can be useful for identifying full-length proteins and protein domains, they are not useful for identifying peptides that may be structurally hindered or peptides that could be used internally in a protein scaffold while retaining the functional activity for which they were selected.  In addition, current phage display systems cannot be used effectively to screen for liver-specific peptides.

A UW–Madison researcher has previously shown that the p17 tail protein of the T7 phage may be used for tagging the virus with a cellular internalization signaling peptide.  This engineered virus can be used as a delivery vehicle for delivering therapeutics to hepatocytes.

UW–Madison researchers have developed a phage display system that utilizes the p17 tail protein of the T7 virus as the fusion target for expressing a library of peptides.  These peptides may include peptides useful for targeting and internalizing the phage into specific cells such as liver cells.  In addition to screening for liver-targeting peptides, the display system can be used to identify ligands with high binding affinities or establish pharmacophores useful in rational drug design.

• Screening families of peptides, including those not previously amenable to phage display
• Screening for two target peptides at one time (one expressed on the coat protein and one on the tail)
• Screening for liver-specific peptides

• Provides a means of screening families of peptides previously not amenable to phage display selection
• Prevents recognition of displayed sequences by natural antibodies
• Enables screening of conformationally constrained peptide libraries
• Allows for the display of a high copy number of candidate peptides or a low copy number of larger peptides

The researchers have used this system to express several libraries and have identified peptides that target endothelial and parenchymal liver cells.

Publications

• Ludtke J.J., Sokoloff A.V., Wong S., Zhang G., Strickland D.K. and Wolff J.A. 2009. Peptide-Mediated Targeting of Hepatocytes Via Low Density Lipoprotein Receptor-Related Protein (LRP). Drug Deliv. 16, 268-273.

Tech Fields

• Drug Discovery & Development : Compound libraries