Efficiency of scFv display on the phage capsid. Lambda phage clones, displaying scFv at the N-terminus of gpD (α-CEA-N-λ), at the C-terminus of gpD (α-CEA-C-λ), or double displaying scFv fused to truncated gpV and GFP at the C-terminus of gpD (GFP/α-CEA-λ) and double displaying scFv fused to truncated gpV and AP at the C-terminus of gpD (AP/α-CEA-λ), were evaluated for the scFv/FLAG display efficiency. On the abscissa are indicated the amount of wild type phage measured in pfu. The amounts of the phage used in ELISA have been normalized relative to wild type phage in order to have identical number of physical particles per well. ELISA was performed by using anti-lambda antibody-coated plates and the displayed scFv co-expressed with FLAG peptyide was revealed by using an anti-FLAG AP-conjugated antibody. Results are expressed as A=A405-A620.