Jamil Shanagar
GE Healthcare, Bio Sciences, 751 84 Uppsala Sweden
Abstract:
Use of alternative bioprocessing techniques gain in notoriety, even as the efficiency of chromatographic and filtration methods increase. Two popular alternative approaches for target capture, or contaminant removal, are polymer aided precipitation (flocculation) and partition between the phases formed by some polymers in aqueous solutions. Cell debris is often rapidly transported to the phase interface in such phase systems. Partition may therefore effect primary clarification and target purification. However, it is challenged by low capacities (often <2 g/L) and high polymer costs. Precipitation methods face challenges related to target dilution on resuspension and polymer removal. GE Healthcare is investigating alternative methods to condition process streams prior to chromatography. A novel inexpensive phase system offering better than 25 g/L antibody (Ab) capacity was formed directly in 10L fermentation feed (5 g/L Ab). It was used to effect both primary clarification and upper phase (UP) recovery of >95% of Ab target in a vertically suspended 20L WaveÔ bag. The UP, which still contained host cell protein (HCP), was filtered and could either be applied directly to an affinity column, or subjected to polymer-assisted, target-selective precipitation (TSP). Over 90% of antibody (Ab) precipitated with TSP, while 95% of both HCP and DNA were in the supernatant. Precipitated Ab could be easily re-dissolved at concentrations and buffer conditions suitable for direct processing by affinity chromatography. Further research is needed to evaluate these approaches, which hold may increase process flexibility while reducing clarification costs.
