filamentous phage display PSI-MI MI:0048 filamentous phage Filamentous phages (M13, f1, fd) have been extensively used to develop and implement the technology of phage display. Repertoires of relatively short peptides of random amino acid sequences or cDNA libraries have been constructed and searched successfully. Most experiments have taken advantage of the ability to assemble phages decorated with hybrid versions of the receptor protein pIII or of the major coat protein pVIII. Both systems allow the display of foreign peptides by fusion to the amino-terminus of the capsid protein but differ in the number of peptide copies that can be displayed on each phage particle. Display libraries of very diverse protein fragments have been constructed by fusing either genomic or cDNA fragments to gene III or gene VIII. phage display