As the newest alternative to Protein A chromatography, the camelid antibody ligand provided very good selectivity for IgG-based
molecules. This resin showed similar binding affinity and somewhat comparable dynamic binding capacity to the commonly used
commercial Protein A resins. For antibodies, it did have a lower capacity than the leading agarose-based Protein A resin;
however, this shortcoming might be compensated by the vendor by further optimizing the ligand density and appropriate resin
pricing. This resin does offer the distinct advantage of being base stable. Different from previously reported mixed mode
and Protein A mimetic ligands, this ligand showed as good host cell protein clearance as the Protein A resins used for comparison.
Although the new resin has been primarily marketed for IgG3 purification, the results presented in this study demonstrate
that this can potentially be used very effectively for industrial MAb purification. Parameters that remain to be evaluated
comprehensively before its widespread acceptance and use are column lifetime and viral clearance. Finally, the binding mechanism
exploration studies indicated a difference in ligand–IgG interactions between the two ligands. For IgSelect, medium to high
concentration of kosmotropic salt should be avoided in the background buffer to maximize antibody recovery during purification.
The authors would like to acknowledge the process biochemistry and analytical groups at Bristol-Myers Squibb for their analytical
Jia Liu, PhD, is a process engineer in process sciences downstream, John L. Hickey is associate director of process sciences downstream and project management, and Sanchayita Ghose, PhD, is the manager of the process sciences downstream group, all at Bristol Myers Squibb Company, Syracuse, NY, 315.431.7930,
Aaron Cheung is a chemical engineering student at the Massachusetts Institute of Technology.
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