AAV Potency Measurement Using ELISA and CryoTEM

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Solution Overview

Problem

Current methods for measuring the quality attributes of gene therapy vector preparations, such as quantitative PCR (qPCR), are limited by variability and inaccuracies due to issues like inefficient primers, calibration standards, and DNA tertiary structures, leading to potential immune responses and therapeutic inefficacies.

Innovation Solution

The use of an AAV-specific enzyme-linked immunosorbent assay (ELISA) in combination with cryogenic transmission electron microscopy (CryoTEM) to quantify the total number of AAV capsids and determine the ratio of full to empty capsids, providing a more accurate and reliable measurement of concentration, dose, and potency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If quantitative PCR (qPCR) is used to measure AAV preparation, then vector genome concentration can be determined, but measurement precision and reliability deteriorate due to variability from inefficient primers, calibration standards, and DNA tertiary structures

Engineering Contradiction:

Improvevector genome concentrationVSAvoiddose measurement accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent replaces the biochemical qPCR system with a physical measurement system (analytical ultracentrifugation) that directly measures capsid concentration without relying on DNA amplification, thereby eliminating errors from primers, calibration standards, and DNA tertiary structures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces capsid protein concentration as an intermediary measurement that correlates with vector genome concentration, using analytical ultracentrifugation to measure capsid physical properties as a more reliable proxy for dosing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If qPCR measures total DNA including empty capsids, then total vector genome signal is obtained, but potency determination becomes inaccurate due to inclusion of non-functional capsids

Engineering Contradiction:

Improvetotal vector genome signalVSAvoidpotency determination accuracy

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent segments the measurement into two independent components: capsid concentration (measured by analytical ultracentrifugation) and genome-to-capsid ratio (measured by qPCR), allowing separate evaluation of functional vs. non-functional particles

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts the capsid measurement from the DNA measurement by using analytical ultracentrifugation to directly quantify capsid physical properties, separating this function from the DNA-based qPCR measurement to eliminate cross-contamination of empty capsid signals

Inventive Principle:

Principle #2Taking out (Extraction)

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 significantly reduces variability in measuring the concentration, dose, and potency of AAV preparations, achieving coefficients of variation between 10% to 80% less compared to qPCR methods, ensuring consistent and accurate clinical dosing.

Implementation Method 1

an AAV-specific enzyme-linked immunosorbent assay (ELISA) to quantify the total number of AAV capsids

Methodology Applied

Scientific EffectAntigen-antibody binding:

Implementation Method 2

cryogenic transmission electron microscopy (CryoTEM) to quantify the total number of AAV capsids and determine the ratio of full to empty capsids

Methodology Applied

Scientific EffectElectron microscopy imaging:

Data Source

PatentEP3589956B1Methods for determining potency of adeno-associated virus preparations

Publication Date: 2025.04.23 TAKEDA PHARMA CO LTD

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AI summary

Provided herein are methods of measuring the qualitative and/ or quantity attributes of gene therapy vector preparations. In certain embodiments, the gene therapy vector preparations are Adeno-associated virus (AAV) preparations (e.g., AAV8). In certain embodiments the methods comprise determining the potency or dose of the AAV preparation using ELISA, or ELISA in combination with cryogenic transmission electron microscopy (CryoTEM).