Promoter Evaluation in the Cellca CHO DG44 Expression System
4th December 2017
Category: Cell Line Development
By: Ann-Catherin Leroux - Scientist, Dr Christoph Zehe - Lead Scientist,
One key component of the powerful Cellca Expression Platform is the expression vector. We have carefully selected its genetic elements to allow:
- freedom to operate
- high level expression of monomeric and dimeric products (e.g. IgG-type antibodies, Fc-Fusion, bispecifics)
- enhanced, stable expression by optimized S/MAR elements
- increased secretion by optimized signal peptide
As a next step in enhancing our platform, we have evaluated several viral and mammalia promoters with regards to their impact on antibody titers and productivity.
First, we designed eight vector variants, each carrying a different promoter. We then transfected our robust CHO DG44 host and screened the resulting pools for titers in batch experiments. Out of the eight variants, the four promoters yielding the highest titers on pool level were chosen for fed-batch experiments. The single promoter allowing highest titer and productivity was selected for expression of four model antibodies. Compared to the previously used promoter, titers were 46 to 212% higher and the final clones showed excellent stability. Hence, we were able to identify a promoter which will allow up to threefold higher titers.