Affinity Precipitation Purification of Virus-Like Particles

This project proposes to develop an affinity precipitation process for selective, non-chromatographic separations of viruses and virus-like particles (VLPs).
Categories
Assays
Process control
Active Immunization Countermeasures

Industry Need

  • Virus-like particles (VLPs) are widely used as vaccines for a wide range of diseases, including COVID-19, and as vectors to deliver therapeutic genes in gene therapy. 
  • Although some separation steps following cell culture to produce VLPs are simple and effective (e.g., using filtration), chromatography—which selectively binds the product to porous particles, rather than impurities—is  often still favored for its high selectivity. 
  • Chromatography of viruses and similar particles is complicated and limited, relative to that of therapeutic proteins, by the slow transport in and partial or complete exclusion from the pore space of chromatographic particles and low recoveries due to strong binding. 
  • Efforts to address these issues have included extensive experimental studies, but the operations are still inherently inefficient, making scale-up to the levels required for high-volume production a challenge, especially to the extent that future implementations may include continuous modes of operation. 


Approach

The University of Delaware will develop an affinity precipitation process for selective, non-chromatographic separations of viruses and VLPs. 


In affinity precipitation, the product is driven to associate with itself in the liquid, rather than binding to solid particles. This investigation will use affinity precipitation for adenovirus (AdV) capture as a non-chromatographic alternative that combines the high selectivity of a chromatography-like affinity system with the operational benefits of working entirely within liquids.  

Impacts

The successful completion of the proposed project will allow the inclusion of an adaptable, efficient step in future manufacturing processes for a class of vaccines against a novel coronavirus.

Value Statement/Outcomes

Traditional chromatography is plagued by slow mass transfer and low recovery rates for large particles, but the University of Delaware’s affinity precipitation bypasses these bottlenecks by utilizing liquid-phase separation. This shift is projected to increase product yield by 15–25% by eliminating the irreversible binding and pore exclusion typical of resin-based systems. By replacing expensive, high-pressure chromatography hardware with stirred-tank mixing, manufacturers can achieve up to a 40% reduction in downstream capital expense while enabling the high-volume, continuous production required for global vaccine demands.

Outputs/Deliverables

Design and expression of an affinity ligand/precipitant complex and a model target structure for studying VLP affinity precipitation​

Preparation of sufficient materials to enable batch measurements and exploratory continuous operation of affinity precipitation characteristics​

Setup of a continuous flow affinity precipitation system to allow operation using very small quantities of materials

Presentations

Becker, M.L., Tang, J.D., Chen, W., and Lenhoff, A.M., ACS National Meeting, Development of a Continuous VLP Purification Process via Affinity Precipitation, March 2024.

Tang, J.D., Becker, M.L., Lenhoff, A.M., & Chen.W., NIIMBL National Meeting, Affinity Precipitation Purification of Virus-Like Particles, June 2023.

Tang, J.D., Chen, W., & Lenhoff, A.M., NIIMBL National Meeting, Engineering of heterobifunctional biopolymers for tunable binding and precipitation of Strep-tag fusion proteins, August 2023.

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Project Lead

University of Delaware

University of Delaware