Outline of several filamentous phage display strategies. A) pVII and pIX display: interacting proteins fused to their N-termini (signal sequences upstream, wild type pVII and pIX provided); pVIII display: large proteins fused to the N-terminus of pVIII displayed at low copy only (wild type pVIII provided); pVI display: proteins fused to the C-terminus displayed, though inefficiently (wild type pVI provided); pIII display: short peptides at the N-terminus of pIII can be uniformly displayed without disrupting infectivity.  B) pVIII display: short peptides at the N-terminus of pVIII can be uniformly displayed without disrupting virus assembly; pIII display: large proteins fused to the N-terminus of pIII (wild type pIII provided). C) Fos-Jun C-terminal display: a Fos-protein X(N) fusion associates with N-terminally displayed Jun-pIII in the periplasm, and the entire sandwich incorporates into virions that contain the X(N) DNA sequence; selectively infective phage (SIP): proteinX(a) fused to the N-terminus of the C-domain of pIII and protein Y(a) fused to the C-terminus of the N1-N2 domains of pIII; X(a)Y(a) interaction makes particles infectious.