Fig. 6.
High fGly conversion yields can be obtained from stably transduced cell lines under high titer cell culture conditions. Stable transduction of DNA encoding FGE, antibody light chain, and antibody heavy chain bearing one (CT only) or two (CH1 and CT) aldehyde tags was performed with viral retrovector transduction into CHO cells (GPEx® technology). The resulting stable pools were cultured in three types of media +/- supplementation with copper(II) sulfate (n = 3). Titers (a) and fGly conversion (b) of CT-tagged antibodies were assessed. Then, the stable pools were cloned by limiting dilution and clone performance was assessed in fed batch cultures (c and d; shake flask, n = 5 clones; bioreactor, n = 3 clones single tag, n = 1 clone double tag). The top performing stable single-tagged clonal cell line produced antibody in very high titer (5.2 g/L) with 98 % conversion of Cys to fGly (c and d). The specific productivity (75 pg/cell/d) of this top clone demonstrates the capabilities of the GPEx® technology for efficient production of highly converted antibody. The generation of fGly in single- and doubly-tagged antibodies scaled successfully to bioreactors (2 L cultures; c and d). Error bars indicate standard deviation