Yanfeng Zhang completed his PhD from Michigan State University and Post-doctoral studies from Pacifi c Northwest National Laboratory and University of Texas Health Science Center at San Antonio. He is Senior Scientist of Process Development of XBiotech, USA, the world’s leading developer of next-generation True Human therapeutic antibodies. He has published more than 20 papers in reputed journals and has been serving as an editorial board member of international journals.


Staphylococcus aureus is gram-positive bacteria that commonly causes human health problem such as skin and respiratory infections, and food poisoning. S. aureus has multiple virulence factors including henolysins, toxins and superantigens, and the strains have high genetic variability. Some strains of S. aureus are also resistant to antibiotics (MRSA and VRSA), resulting in an infection that is diffi cult to control. XBiotech has screened the blood of hundreds of human individuals to fi nd antibodies that directly and specifi cally target S. aureus. One of these true-human antibodies, 514G3, has shown positive results in preclinical studies against S. aureus and is currently being evaluated in a Phase I/II study. During the purifi cation of 514G3 antibody, an unusually high level of protein aggregation (up to 20%) was observed. Th erefore, the protein aggregation problem was fi rst analyzed by a series of analytical methods. Th en, downstream processes were developed to remove the aggregated antibodies. Th is presentation will describe our strategies of resin screen and optimization for the removal of antibody aggregates.

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