Epitope mapping using libraries of random peptides displayed on phage

Abstract

Abstract In 1985 Young et al. (1) introduced a method for cloning immunoreactive sequences, such as bacterial surface antigens, by expressing the proteins in X. plaques and identifying the clones of interest by probing with the appropriate antibodies. This method relied on the co-localization of the reactive peptide with the cloned DNA in a plaque or colony. This is a powerful technique, but it is difficult to screen more than a few million clones by this approach. Alternative methods, relying on the physical linkage of the protein and DNA, have recently become practical. These methods are known as peptide display techniques, and comprise the cloning of sequences that are expressed as peptides or proteins fused to a carrier protein and displayed on the outer surface of microorganisms. The surface peptide is immunoreactive, and the encoding DNA is carried within the microorganism. The clones of interest are isolated by affinity purification of the exposed peptides on a matrix of immobilized antibody or other binding protein. This approach, because it provides for the efficient isolation of individual microorganisms from a complex mixture, allows the screening of extraordinarily large numbers of clones.