Display of a full length IgG antibody on the surface of Escherichia coli: Towards the screening of an antibody library

Dilkaute C, Weckenbrock W, Jose J

Abstract

Phage display is an often used technique to identify new antibody variants. Nevertheless, it isassociated with some drawbacks as the possible discrimination of the most potent binders duringbiopanning, the incompatibility with flow cytometry or the size limitation of the protein displayedon the surface [1]. To circumvent these disadvantages, we presented a full-length antibody on thesurface of Escherichia coli using the autodisplay technique [2,3]. As a proof of principle, the displayof antibody T84.66, which is directed against carcinoembryonic antigen (CEA), was investigated.Based on this antibody a library was generated using a ligation-restriction strategy. The resultinglibrary consists of up to 105 clones which could be analyzed via flow cytometry after incubation witha fluorescently labelled target protein. To examine the optimal conditions for the screening, twodifferent autotransporters in combination with two promoters were investigated: the AIDA-1autotransporter [2] under control of a T7 promoter and the EhaA-autotransporter [3] controlled byan araBAD promoter. Experiments with the T84.66 antibody revealed that the EhaA-araBADcombination suited better with regard to surface presentation and cell survival after sorting. Theseresults indicate that it is possible to generate a full-length antibody library on the surface of E. coli.This library can be screened with the advantageous high-throughput screening system of flowcytometry.Keywords: antibody