Phage display services for antibody discovery

Antibody library generation is a vital first step in all phage display projects. The process encompasses the recovery of the naïve or immune antibody repertoire from specific host species by harvesting their B lymphocytes (B cells) or isolating PBMCs (peripheral blood mononuclear cells) by density gradient centrifugation of blood samples. The diversity of these repertoires is subsequently seized by mRNA extraction, cDNA synthesis, and PCR-mediated amplification of antibody-encoding genes.

Naïve libraries are prized for their versatility (adaptability to different projects/antigens) while immune libraries are considered more labor-intensive and reserved for especially challenging projects aiming to boost antibody affinity and selectivity.

Interested in our naïve library screening service or in constructing an immune library? Please feel free to contact our dedicated account manager.

ProteoGenix developed a large choice of proprietary phage display libraries that you can adapt to all your projects. Our goal is to fulfill all your unique requirements and to always push the boundaries of innovation by creating new and better phage display libraries. Whether you need a fully human antibody or a nanobody for therapeutic applications or a high-affinity rabbit antibody for diagnostic applications, our libraries will help you overcome your most difficult challenges. Feel free to contact our account manager for more information.

“All three of the antibodies you delivered were reformatted into IgGs and worked well. Interestingly two were d1 binders, and one was a d1/d2 binder when we domain mapped them here. They were good “protein X” blocking antibodies. But none were “protein Y” blockers. They express reasonably well. Overall we are quite happy with them.”

“ProteoGenix has been generous and sincere in supporting an academic laboratory like ours. They were able to identify several antibody sequences via phage display against a protein antigen and they screened twice more phages than initially planned to help us succeed in our project. ProteoGenix team was reactive and diligent in their replies and services.”

“We are developing a novel immunotherapy and needed a highly potent monoclonal antibody. Currently the development of a novel antibody requires lengthy and expensive humanization process. We thus decided to screen for binders a human antibody library via phage display screening instead of humanizing a murine antibody. Proteogenix proposed just that. We provided our purified target antigen and in only one month several high affinity binders were obtained. We were able to quickly clone and produce a monoclonal antibody from the sequences provided. What should have taken 6 to 8 months was done in 2 for a fraction of the cost and for an equivalent quality.”

The phage display technology encompasses the determination of interaction partners of a specific protein (protein-protein, protein-DNA, or protein-peptide). These interactions can subsequently be used as “bait” to capture phages displaying peptides, proteins, or antibodies encoded in high diversity DNA libraries. Through the interactions, it becomes possible to determine the function of a specific peptide or protein.

Phage display cycle: phage display library, panning/biopanning and validation by ELISA

The phage display technique commonly employs filamentous phages such as phage M13 from Escherichia coli. This method has proven to be a powerful way to interrogate libraries containing billions of different proteins or peptides.

The application of phage display on large antibody libraries has led to real success in the isolation of highly selective and specific monoclonal antibodies.

The use of libraries composed of billions of antibodies displayed on phages offers a highly valuable and effective alternative to traditional methods of antibody generation by allowing the quick selection of the most relevant candidates for your research.

All ProteoGenix’s antibody phage display libraries are made using the filamentous phage M13, a virus infecting the bacterium E. coli. M13 is a lysogenic phage, comprised of a circular and single-stranded DNA encased in a thin flexible tube coated by about 2700 copies of protein pVIII, the major coat protein, and about 5 copies of pIII, the minor coat protein, present at the ends of the tube.

Infection with M13 plasmids is not lethal for bacteria and they are used for many recombinant DNA processes. Antibodies are generally displayed as fragments such as single-chain variable fragments (scFv), antigen-binding fragments (Fab), or variable heavy-chain antibody fragments (VHH or nanobodies).

These fragments are typically fused to protein pIII and cloned into a phagemid vector, comprising a simplified version of phage M13 containing only the pIII-antibody fusion protein, an origin of replication, and a selection marker (e.g., antibody resistance gene).

The phagemid vector is used in conjugation with a helper phage which, in turn, contains all essential elements of phage M13 except for a slightly defective origin of replication and no antibody fragments. The co-transformation of these two elements in E. coli results in the expression of hybrid phage particles generally displaying a single pIII-antibody fusion protein alongside native pIII proteins (essential for infection).

The reduced abundance of antibodies displayed per phage particle ensures only the binders with the highest affinity are selected during the process of biopanning.