Anti-CEA reactivity of the phage clones displaying anti-CEA scFv and GFP. Lambda phage, displaying simultaneously GFP at the C-terminus of gpD and anti-CEA scFv antibody as fusion to the C-terminus of the truncated gpV tail protein (GFP/α-CEA-λ) was tested by ELISA against purified CEA and an irrelevant control protein (GST). Wild type phage λKM4 was tested as a negative control. The phage α-CEA-N-λ and α-CEA-C-λ displaying scFv antibody at the N- or C-terminus of the gpD respectively, were included as positive controls. The bound phage was detected by using rabbit anti-lambda polyclonal antibody. Results are expressed as A=A450-A620. Data reported are the average values of assays performed in duplicate. Error bars represent the standard deviation of the mean.