The removal of viruses from process streams is an extremely important problem to the pharmaceutical industry, as more products are being produced from human or cell-based sources. Commonly, nanofiltration or chemical deactivation is used to remove viruses from therapeutic produces. A less frequently used method is affinity absorption in a chromatographic format. Most ligands for affinity adsorption are antibodies, which can be difficult and expensive to produce in large quantities, and which may become contaminated with viruses during their production. Small peptides as short as three amino acids in length have been discovered that bind to porcine parvovirus (PPV) and can remove PPV from samples containing 7.5% human blood plasma. PPV is often used as a model virus for virus removal due to its small size and its ability to withstand chemical deactivation by surfactants or changes in pH.

The trimeric peptides were found from the screening of a combinatorial library that was produced on the same chromatographic support that is used for the actual separation process. This screening method is superior to other methods because it reduces the chance that the peptide may not bind the virus when transferred to a different support, as often happens when screening peptides with phage display libraries. This method has been used to find ligands that bind to many different proteins, including the staphylococcal enterotoxin B.

The discovered trimer peptides that bind to PPV are being optimized to increase their binding affinity under processing conditions. The optimization includes determining if the presence or absence of a spacer arm improves binding of the peptide ligands and by varying the peptide density on the surface of the resin bead to find the optimal binding conditions.

There are also many other uses for these small peptides, including the removal of viruses from process streams, concentration of viral vectors for gene therapy, and molecular surface detection for use in a sensor. These small peptide ligands have promising uses in many areas of virus capture, and the use will be determined by the ease of elution that is needed for each application.