Flow-Through Capsid Polishing for Full and Empty AAV Separation

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Solution Overview

Problem

The separation of full and empty viral capsids, particularly adeno-associated virus (AAV) particles, is challenging due to their identical capsid structure, leading to inefficiencies in existing methods like immunoaffinity chromatography, and current techniques such as density gradient centrifugation and anion exchange chromatography are time-consuming and require expensive equipment.

Innovation Solution

A novel flow-through polishing method using a stationary phase that allows full capsids to bind while empty capsids do not, followed by a one-step elution with a higher salt concentration, enabling separation without complex equipment like FPLC systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If density gradient centrifugation or anion exchange chromatography is used to separate full and empty capsids, then separation is achieved, but the process is time-consuming and requires expensive equipment

Engineering Contradiction:
Improveseparation efficiencyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The invention changes the salt concentration parameter to achieve separation. Full capsids bind to the stationary phase at low salt concentration and are eluted at high salt concentration, while empty capsids flow through. This parameter-based separation eliminates the need for time-consuming centrifugation or complex chromatography equipment.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention extracts the binding capability from the capsid-DNA complex by using a stationary phase that specifically binds full capsids. This allows separation without requiring the complex equipment of density gradient centrifugation or anion exchange chromatography systems.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If density gradient centrifugation or anion exchange chromatography is used to separate full and empty capsids, then separation is achieved, but expensive equipment like FPLC systems is required

Engineering Contradiction:
Improveseparation efficiencyVSAvoidequipment complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention uses a simple stationary phase that can be disposed of or regenerated, eliminating the need for expensive FPLC systems. The method achieves separation using basic laboratory equipment, making it accessible for research and development without requiring costly instrumentation.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention replaces the mechanical centrifugation system or complex chromatography system with a simple binding-elution process. The stationary phase provides the separation mechanism through chemical binding rather than mechanical forces, simplifying the equipment requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If immunoaffinity chromatography is used for capture, then purification is achieved, but separation of full and empty capsids remains inefficient

Engineering Contradiction:
Improvepurification reliabilityVSAvoidseparation precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention applies local quality by using a stationary phase with specific binding properties that differentiate between full and empty capsids. The stationary phase is designed to bind only full capsids at specific salt concentrations, creating a localized separation mechanism that complements the immunoaffinity capture step.

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method provides a rapid, easy, and cost-effective way to separate full and empty capsids, preserving their functional potency and structural integrity, suitable for research and development of gene therapies.

Implementation Method 1

contacting the viral capsid preparation with a stationary phase surface allowing binding of the full viral capsids to the stationary phase surface

Methodology Applied
Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

conducting an one-step elution and/or linear salt gradient elution in which the full capsids are eluted by contacting the stationary phase obtained in step (ii) with an elution solution comprising a second salt concentration

Methodology Applied
Scientific EffectSalt gradient elution: Ion Exchange

Data Source

PatentEP4670812A1Flow-through polishing of viral capsids
Publication Date: 2025.12.31 SARTORIUS STEDIM BIOTECH GMBH
  • EP4670812A1 patent drawingFigure 1A~1B
  • EP4670812A1 patent drawingFigure 1C~1D
  • EP4670812A1 patent drawingFigure 2A~2B

AI summary

The invention relates to a method of separating empty viral capsids and full viral capsids, the method comprising: providing a viral capsid preparation comprising the empty viral capsids and the full viral capsids, wherein the viral capsid preparation comprises a first salt concentration; contacting the viral capsid preparation with a stationary phase surface allowing binding of the full viral capsids to the stationary phase surface, wherein the empty viral capsids at least partially do not bind to the stationary phase surface; and conducting a one-step and/or linear elution in which the full capsids are eluted by contacting the stationary phase obtained in step (ii) with an elution solution comprising a second salt concentration, wherein the first salt concentration is lower than the second salt concentration.