PROBING THE BASIS OF ANTIBODY REACTIVITY WITH A PANEL OF CONSTRAINED PEPTIDE LIBRARIES DISPLAYED BY FILAMENTOUS PHAGE

The structural requirements for peptide binding to an antibody may be elucidated by probing it with a variety of peptides having different c onstraints. To this end, we have constructed and screened a panel of p eptide libraries displayed by filamentous bacteriophage. The peptides in most of the libraries have the potential for constraint by fixed Cy s residues, which have been placed at different sites within a randomi zed amino acid sequence of varying length. When taken together, the bi nding data obtained from screening the panel with a given antibody all ow one to determine the types of constraints that promote binding, as well as the residues that are critical for binding. We describe the co nstruction of 11, pVIII-displayed, peptide libraries, whose sizes rang e from 150 million to 10 billion clones. The libraries were screened w ith a number of polyclonal and monoclonal antibodies against peptides, proteins and carbohydrates. Cross-reactivity with peptides was always found for antibodies produced against peptides, linear epitopes on fo lded proteins and, surprisingly, carbohydrates, whereas antibodies aga inst discontinuous epitopes on proteins were found less frequently The implications of these results are discussed in terms of the structura l basis for cross-reactivity with peptides. (C) 1996 Academic Press Li mited