Baculovirus-free insect cell expression system for high yield antibody and antigen production

Janin Korn,Esther Veronika Wenzel,Dorina Schäckermann,Kristian Daniel Ralph Roth,Michael Hust,Maren Schubert,Janyn Heisig,Joop Van Den Heuvel,Stephan Steinke,Gertrudis Rojas,Marlies Becker,Nora Langreder,Stefan Dübel,Federico Bertoglio,Doris Meier,Toni Kirmann,Maximilian Ruschig

doi:10.1038/s41598-020-78425-9

Abstract

Antibodies are essential tools for therapy and diagnostics. Yet, production remains expensive as it is mostly done in mammalian expression systems. As most therapeutic IgG require mammalian glycosylation to interact with the human immune system, other expression systems are rarely used for production. However, for neutralizing antibodies that are not required to activate the human immune system as well as antibodies used in diagnostics, a cheaper production system would be advantageous. In our study, we show cost-efficient, easy and high yield production of antibodies as well as various secreted antigens including Interleukins and SARS-CoV-2 related proteins in a baculovirus-free insect cell expression system. To improve yields, we optimized the expression vector, media and feeding strategies. In addition, we showed the feasibility of lyophilization of the insect cell produced antibodies. Furthermore, stability and activity of the antibodies was compared to antibodies produced by Expi293F cells revealing a lower aggregation of antibodies originating from High Five cell production. Finally, the newly established High Five expression system was compared to the Expi293F mammalian expression system in regard of yield and costs. Most interestingly, all tested proteins were producible in our High Five cell expression system what was not the case in the Expi293F system, hinting that the High Five cell system is especially suited to produce difficult-to-express target proteins.

Highlights

Antibodies are essential tools for therapy and diagnostics
We compared antibody quality in regard of stability and aggregation behaviour when produced in insect cells to those produced in the mammalian Expi293F cell system
The influence of the Kozak sequence, the insertion of an intron inside the secretion signal and two different secretion signal peptides were tested resulting in four different expression vectors

Summary

Introduction

Antibodies are essential tools for therapy and diagnostics. Yet, production remains expensive as it is mostly done in mammalian expression systems. The baculovirus expression vector system (BEVS) still is not optimal for the production of secreted proteins as the virus infection negatively affects the secretory pathway of its host c ells[15]. This impairs both yield and protein quality, in particular when the highly active but very late promoters polH or p10 are u sed[16]. We tested whether media supplements increase expression of antibodies After this optimization of the system towards secreted proteins, we confirmed the possibility to lyophilize antibodies produced in insect cells. We compared production yields of different secreted proteins in our insect cell expression system to those obtained using Expi293F cells

Methods

Results

Conclusion