A novel strategy for proteome-wide ligand screening using cross-linked phage matrices.

To find a suitable ligand from a complex antigen system is still a mission to be accomplished. Here we have explored a novel "library against proteome" panning strategy for ligand screening and antigen purification from a complex system using phage-displayed antibody technology. Human plasma proteome was targeted for phage library panning. During the process, the panning was carried out in solution, using a biotin/streptavidin beads separation system, for three rounds. Nine monoclonal phages, bound tightly to a number of unknown plasma proteins, were selected from the last round, six of which were directly employed as cross-linked matrices to purify their corresponding antigens from the plasma. The proteins isolated by G5 and E1 matrices were identified as amyloid protein and apolipoprotein A-I precursor, respectively. The results demonstrated that it was feasible to simultaneously obtain a number of ligand phages for various antigens, including low abundant proteins in a non-comparative proteome-wide system.