Expression of a Self-Assembling Antigen-Targeting Fusion Protein

Cassidy Brady

August 1, 2012

3 Min Read


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The Pfēnex Expression Technology™ platform is a very powerful protein expression technology based on the microorganism, Pseudomonas fluorescens. The Pfenex platform can deliver a robust production strain with unprecedented speed and a success rate that transcends legacy production hosts. Traditional recombinant protein expression hosts such as E. coli, insect cells, and yeast tend to have high failure rates regarding their ability to produce high titers of soluble, full-length, active target protein. In addition, the time required to identify the optimal expression strain in these systems is protracted due to a linear and iterative approach to strain engineering, resulting in significant opportunity cost for the drug developer. Pfēnex Expression Technology™ dramatically reduces strain development time and hence product development time through robotically enabled high-throughput, parallel expression strain screening. The resultant selected production strain delivers a lower overall cost of goods associated with rapid fermentation cycle times, higher cell densities, and low cost media. The combination of speed, success rate, and reduced cost of goods has established Pfēnex Expression Technology™ as the premier technology for recombinant protein production.

Overview: The following case study, presented by Mark C. Poznansky, MD, PhD, director of the Vaccine and Immunotherapy Center at Massachusetts General Hospital, outlines the improved expression and purification of a fusion protein using Pfēnex Expression Technology™, after bacterial and insect cell systems were attempted with limited success. Expression with the legacy hosts resulted in inclusion bodies, denatured protein, additional and challenging refolding steps, as well as low recovery of active protein. Within a matter of weeks using Pfēnex Expression Technology™, a scalable production strain was identified that was capable of producing approximately 1.4 g/L of soluble and active target protein (Figures 1 and 2).


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Pfenex Expression of Fusion Protein

The Pfēnex Expression Technology™ platform offers a robust solution to the real and opportunity costs incurred through the maintenance of several recombinant expression platforms. The value to the drug developer is clear; there are significant opportunity and real costs associated with using the antiquated linear, and iterative approach to production strain engineering. Even with smaller-scale programs, there is still the utmost importance placed on speed, while not sacrificing quality and quantity of protein delivered. Using the Pfēnex Expression Technology™ platform in discovery and throughout the development program provides tangible benefits in expediting programs by efficient protein production, allowing programs to avoid attrition due to inability to produce product. The platform also delivers a reduced long-term cost of goods that will have a sustainable competitive advantage against other competing products, including biosimilars.

About the Author

Author Details
Cassidy Brady is marketing and business development manager at Pfenex Inc., 10790 Roselle Street, San Diego, CA 92121; 1-858-352-4400, fax 1-858-352-4602; [email protected];

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