phagedisplayed

Phagedisplayed, commonly referred to in the literature as phage display, is a molecular biology technique that enables the presentation of peptides or proteins on the surface of bacteriophages, typically filamentous phages such as M13. The displayed product is genetically fused to a phage coat protein, linking the phenotype (the displayed molecule) to its genotype (the corresponding DNA inside the phage). This platform supports libraries encoding short peptides, antibody fragments, and other protein scaffolds, making it a versatile tool for studying interactions and selecting binding partners.

In practice, DNA sequences encoding displayed molecules are inserted into a phage coat protein gene (most often pIII or pVIII) so that each phage particle carries the encoded peptide or protein on its surface. The library is exposed to a target immobilized on a surface; phages that bind are retained while non-binders are washed away. Bound phages are eluted, amplified in bacteria, and subjected to several rounds of selection (panning) to enrich high-affinity binders. After several rounds, individual phage clones are characterized and sequenced to identify the binding molecules.

Applications of phage display include discovery and optimization of antibodies and antibody fragments, ligands for receptors, enzymes, and diagnostic reagents. It is used for epitope mapping, vaccine design, and affinity maturation in directed evolution experiments. The technique has played a significant role in therapeutic antibody development and in exploring protein–protein interactions, often complementing other display platforms and screening approaches.

Limitations and considerations include biases in library representation, constraints of the display format, and difficulties displaying conformationally complex or membrane-associated proteins. Phage display is typically conducted in bacterial systems, which lack certain eukaryotic post-translational modifications, potentially affecting selection outcomes. Variants include alternative phage platforms and other display methods (for example, yeast or T7 display) that address specific research needs.