Inclusion of an upstream transcriptional terminator in phage display vectors abolishes background expression of toxic fusions with coat protein g3p.

Expression of toxic gene products affects bacterial cell growth and phage display, causing a strong selection against plasmid maintenance and integrity. During phage propagation steps, in particular, phagemid instability can dramatically affect diversity of antibody libraries or even lead to the deletion of antibody genes. We constructed a modified phage display vector by introducing a strong transcriptional terminator upstream of the lac promoter, which together with glucose suppression of its CAP-dependent activation, very efficiently represses product formation before induction.