Viral Vector Manufacturing 101

Downstream: Purifying the Product

At harvest, the vector particles are present in a mixture along with cell debris, proteins, and DNA. Downstream processing isolates and concentrates the functional vector. Typical steps include:

Clarification - removing cells and debris by filtration or centrifugation
Purification - using chromatography (affinity, ion-exchange, or size-based) to separate vector from impurities (e.g. host cell proteins)
Concentration and Buffer Exchange - often via tangential flow filtration (TFF) to reach the final formulation

Note: While ultracentrifugation is still often used for purification and/or concentration, this unit operation is difficult to scale and generally replaced by chromatography for larger-scale clinical manufacturing.

Downstream viral vector purification workflow illustrating clarification, chromatography, and filtration steps used to purify AAV and or lentiviral vectors for cell and gene therapy manufacturing.

Downstream processing removes impurities and concentrates functional vector. Typical steps include clarification, chromatography, and filtration.

Details to think about:

Process choices depend on vector type: AAV vs. lentiviral vector (LVV) require different chromatography resins and filtration steps
Empty/full particle separation: critical for improving AAV quality
Scalability: each purification step must balance yield, purity, and cost