High level transient production of recombinant antibodies and antibody fusion proteins in HEK293 cells

Volker Jäger,Konrad Büssow,Andreas Wagner,André Frenzel,Susanne Weber,Michael Hust,Thomas Schirrmann

doi:10.1186/1472-6750-13-52

Abstract

BackgroundThe demand of monospecific high affinity binding reagents, particularly monoclonal antibodies, has been steadily increasing over the last years. Enhanced throughput of antibody generation has been addressed by optimizing in vitro selection using phage display which moved the major bottleneck to the production and purification of recombinant antibodies in an end-user friendly format. Single chain (sc)Fv antibody fragments require additional tags for detection and are not as suitable as immunoglobulins (Ig)G in many immunoassays. In contrast, the bivalent scFv-Fc antibody format shares many properties with IgG and has a very high application compatibility.ResultsIn this study transient expression of scFv-Fc antibodies in human embryonic kidney (HEK) 293 cells was optimized. Production levels of 10-20 mg/L scFv-Fc antibody were achieved in adherent HEK293T cells. Employment of HEK293-6E suspension cells expressing a truncated variant of the Epstein Barr virus (EBV) nuclear antigen (EBNA) 1 in combination with production under serum free conditions increased the volumetric yield up to 10-fold to more than 140 mg/L scFv-Fc antibody. After vector optimization and process optimization the yield of an scFv-Fc antibody and a cytotoxic antibody-RNase fusion protein further increased 3-4-fold to more than 450 mg/L. Finally, an entirely new mammalian expression vector was constructed for single step in frame cloning of scFv genes from antibody phage display libraries. Transient expression of more than 20 different scFv-Fc antibodies resulted in volumetric yields of up to 600 mg/L and 400 mg/L in average.ConclusionTransient production of recombinant scFv-Fc antibodies in HEK293-6E in combination with optimized vectors and fed batch shake flasks cultivation is efficient and robust, and integrates well into a high-throughput recombinant antibody generation pipeline.

Highlights

The demand of monospecific high affinity binding reagents, monoclonal antibodies, has been steadily increasing over the last years
We started with pCMV standard vectors and transient expression in HEK293T cells which already achieved more than 20 mg/L volumetric yields per day
Taken together, transient expression in HEK293-6E combined with optimized expression vectors and fed batch processes provides robust and versatile production of up to 600 mg/L recombinant IgG-like Single chain fragment variable (scFv)-Fc antibodies

Summary

Introduction

The demand of monospecific high affinity binding reagents, monoclonal antibodies, has been steadily increasing over the last years. The increasing demand of monospecific detection reagents, antibodies, for all human gene products is one of the biggest challenges to investigate the protein function and interaction [1,2,3]. We have demonstrated that phage display selection with our universal human naïve antibody gene libraries HAL4/7/8 can Single chain fragment variable (scFv) consisting only of the variable (V) regions of immunoglobulin (Ig) light (L) and heavy (H) chain connected by a soluble and flexible oligopeptide can be fused to the IgG Fc moiety. The resulting scFv-Fc format has properties of IgGs like bivalency, tag-free detection with standard secondary antibody conjugates and Fc-mediated effector functions [6,7]. The generation of high producer cell lines has been dramatically improved and accelerated [26,27], it is still too expensive, time-consuming and laborious for research applications, if large numbers of individual antibodies have to be produced

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