PHAGE DISPLAY LIBRARY GENERATION
Scientists insert variable DNA sequences coding for their proteins of interest into plasmids that carry a phage coat protein gene, an antibiotic resistance gene, and a packaging signal. Then they transform the plasmids into a bacterial vector and infect it with a helper phage that supplies the other necessary viral proteins. This generates the phage library, where each virion expresses versions of the protein of interest on its coat protein and carries its genetic sequence in its genome.
AFFINITY PURIFICATION
In the next step, researchers isolate the phages expressing surface proteins using a surface ligand binding assay. The final eluted phages may bear a mix of different surface protein epitopes.
PHAGE AMPLIFICATION
In the amplification step, researchers propagate the eluted phages in a bacterial culture, and may run additional rounds of affinity purification.
CLONE ISOLATION
Researchers infect bacteria with the selected phages and culture them on plates containing antibiotics. In the final step, they pick resistant colonies to isolate the plasmids, which are then sequenced and cloned into the desired protein production vectors for various applications.
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