A novel baculovirus based display method for the generation of monoclonal antibodies (BacDimAb)

• Applicant: Dr. Maren Schubert
• Subject Area: Biochemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517704262

Monoclonal antibodies belong to the most important therapeutics worldwide and are irreplaceable as significant research tools. Phage display is currently the most successful technique to generate such monoclonal antibodies. While phage display indeed can select highly affine antibodies very efficiently, additional important parameters like produciblity and developability are not covered by this prokaryotic system. Therefore, a selection method using both the final drug format and production system right from the start would be very valuable. Consequently, a display on mammalian cells is optimal, but such systems cannot be compared so far to phage display in respect of library diversity or time expanse. We aim to develop a novel baculovirus based display method, which eliminates the disadvantages of both phage display and mammalian cell display but combines their advantages all in one integrated selection pipeline. A baculovirus system is optimal suited as an antibody identification system as baculovirus infection by more than one baculovirus per cell is restricted by biological mechanism what allows the required coupling of pheno- and genotype. Simultaneously, baculovirus libraries with a very high diversity can be obtained in a reasonable amount of time. Hereto, former approaches relied on the rare events of homologous recombination for bacmid generation, what did not lead to a convincing technology. In contrast, we will employ the transposon based Bac-to-Bac system to generate larger recombinant bacmid libraries more efficiently. The in E.coli obtained high recombinant bacmid diversity will be preserved during conversion to baculovirus by an optimized highly efficient transfection of the large bacmid (~120 kbp) into Sf21 insect cells. Sf21 cells will produce the respective baculovirus library that can be stored over long time using cryoprotectants and is the starting point for the panning process. For panning Sf21 cells might be used in the first selection rounds, as they in parallel produce an enriched baculovirus library simplifying the process. In the final panning round the use of Expi293F cells will be favored, what is possible as baculovirus can infect (but not replicate in) mammalian cells. Finally, we will evaluate our system and hereto compare our method directly to phage display, what is possible by our validated phage display platform. In summary, our envisioned baculovirus based display will aim to allow screening of the antibodies in the drug format (IgG) of a >1010 library with at least one selection round in the final production system (mammalian cells) in ~1-2 weeks.In total, our proposed baculovirus based display will have a very broad positive impact on future drug development by optimizing and speeding up therapeutic antibody development against any target.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Stefan Dübel; Professor Dr. Michael Hust