Fig. 1.

Dual-display for the identification of antibody–antigen pairs by library-against-library selection. A library of antigens (or antibodies) is displayed on phage, and a library of antibodies (or antigens) is displayed on yeast. The two libraries are mixed, and phage that are not bound to yeast cells are washed away. Phage that are bound to yeast cells are labeled with a fluorescence reagent, and flow cytometry sorting is used to select yeast cells bound to phage. The yeast and phage are separated for amplification, and the selection round is repeated until significant enrichment of pairs has been achieved. During the final round of selection, single cells of phage-positive yeast are sorted into 96-well plates. By eluting the phage from a single yeast cell, the information link between the platforms is maintained, and clonal pairs of antigens and antibodies are isolated.