Phage display is a laboratory technique for the study of protein–protein, protein–peptide, and protein–DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes them. This technology lies on the fact that the gene encoding the displayed molecule is packed within the same virion as a single-strained DNA (ssDNA) and the displayed peptides or proteins are expressed in fusion with phage coat protein.

The phage display technique allows the creation of libraries containing up to 10^12 different variants and could be used for affinity screening of combinatorial peptide libraries to study protein-ligand interactions and to characterize these ligands, receptor and antibody-binding sites, define epitopes for monoclonal antibodies, select enzyme substrates and screen cloned antibody repertoires. One of the most widely used library methodologies is based on the use of filamentous phage (e.g., M13), a virus that lives on E. coli and one of the most successful applications of phage display has been the isolation of monoclonal antibodies using large phage antibody libraries.

By using the phage display technology, Alpha Lifetech Inc. can offer the scientist an advanced platform to produce a high-affinity and high-specificity antibodies, including nanoantibody, diabody, chimeric antibody (such as humanized antibody), VHH single domain antibody and special monoclonal antibody (which can't be produced by hybridoma), in a very short turnaround time. Alpha Lifetech Inc. produces various antibodies based on M13 phage display system for clients, but also accepts customers' requests to yield antibodies or proteins in T4 phage display system or T7 phage display system.