Production of Antibody Fab Fragments in Escherichia coli

Tachibana, Hiroshi; Takekoshi, Masataka

A phage-display library is the most broadly used platform for preparation of recombinant human monoclonal antibody Fab fragments. Panning is effective for the selection of immunoglobulin genes from naïve and immune libraries. However, it is possible to bypass the phage display system if human peripheral lymphocytes are obtained from seropositive patients with infectious diseases as a source of immunoglobulin genes. Direct screening of bacterial colonies producing Fab fragments by colony blotting using filter membranes is practical for the isolation of human Fab fragments to major antigens of pathogens. An oligoclonal culture can also be used, and is a partial application of Epstein-Barr virus transformation of peripheral lymphocytes. Using these procedures, neutralizing antibody Fab fragments to various antigens can be obtained with a sufficient level of cloning efficacy. Chain shuffling and site-directed mutagenesis are also useful ways to improve the quality of the cloned antibody Fab fragments.