Expression of Recombinant Antibodies

Frenzel, André; Hust, Michael; Schirrmann, Thomas

The yield of functional scFv fragments has been improved by co-or overexpression of GroES/L, peptidyl prolyl-cis,transisomerase FkPa, or other folding helper proteins (62-66). Functional expression can also be increased by optimization of cultivation parameters, such as temperature, media, or additives. Here, the optimal parameters are dependent on the individual antibody fragment (58, 67). The production system itself influences the production rate. Very high yields of antibody fragments produced in E. coli are mainly provided by high-cell density fermentation in bioreactors: the expression of a hapten-specific scFv produced in a bioreactor (68) lead to yields up to 1.2 g/L compared to 16.5 mg/L yield of the same antibody obtained by optimized shake flask production (69), which can be mostly addressed to the over 100-fold higher cell density in the bioreactor. A recent production system is the LEX bubble column bioreactor. Yields in the LEX system of an anti-MUC1 scFv was ∼30-40× higher and yields of an anti-lysozyme antibody was about 2× higher compared to shake flask incubation (67, 70). E. coli strain optimization, e.g., plasmid stability, can additionally improve production yield (71).