Phage Display Selection of Antibody Libraries: Screening of Selected Binders

Phage display selection of antibody libraries is a powerful method for generating and evolving monoclonal antibodies. The pComb3 phagemid family of phage display vectors facilitates the mining of antibody libraries in Fab format from human and nonhuman antibody repertoires. Here, we describe the screening for monoclonal Fab binders after selection of a polyclonal pool of Fab binders to an antigen of interest, with the goal of identifying and sequencing monoclonal antibodies that bind the antigen with high affinity and specificity. The screening cascade involves a phage ELISA, followed by a crude Fab ELISA and DNA fingerprinting and sequencing. The protocol outlines phage and crude Fab ELISAs using purified antigen immobilized on microplates, native antigen expressed on eukaryotic cells, or both.