Nucleic Acid Probe Tm Adjustment for qPCR Variability

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Solution Overview

Problem

Current quantitative PCR (qPCR) methods face challenges due to instrument-to-instrument variability, insufficient quality control, particularly with PCR inhibitors, and high costs, which limit their suitability for diagnostics and require complex workflows and skilled labor, making them expensive and difficult to deploy widely.

Innovation Solution

A method that reduces the effect of hybridization probes on amplification by using probes with a melting temperature less than the PCR amplification temperatures, either by designing probes with mismatched bases or using chemical denaturants, allowing for more accurate and sensitive detection of nucleic acid targets while minimizing the impact of inhibitors and reducing reagent consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional qPCR methods are used with standard hybridization probes, then detection capability is achieved, but instrument-to-instrument variability and insufficient quality control limit diagnostic suitability

Engineering Contradiction:
Improvediagnostic suitabilityVSAvoidinstrument-to-instrument variability
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by modifying the probe melting temperature relative to PCR amplification temperature. Specifically, probes are designed with Tm values below the denaturation, annealing, and extension temperatures used in PCR cycles. This parameter adjustment reduces probe effects on amplification kinetics and minimizes instrument-to-instrument variability, thereby improving reliability for diagnostic applications.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If replicate measurements are used to control for false negative and positive results, then some quality control is achieved, but additional sample consumption is required

Engineering Contradiction:
Improvequality controlVSAvoidsample consumption
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent resolves this contradiction by changing the probe temperature parameter to reduce probe effects on amplification. This allows for more reliable single-replicate measurements with improved quality control, eliminating the need for multiple replicates and thereby reducing sample consumption while maintaining or improving reliability.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If low RNA yield from clinical samples is used, then sample availability is maintained, but the number of assays per test is limited

Engineering Contradiction:
ImproveRNA yieldVSAvoidnumber of assays per test
Core Design Contradiction:
Quantity of substanceVSProductivity

Solution Approach 1:

The patent applies parameter changes to probe design (lower Tm relative to PCR temperatures) that improve amplification efficiency and reduce reagent consumption. This enables more assays to be performed per test with the same low RNA yield from clinical samples, thereby increasing productivity without requiring additional sample input.

Inventive Principle:
Principle #35Parameter changes

4Adaptability or versatility

If more tests are performed to increase diagnostic capability, then comprehensive analysis is achieved, but expensive reagents and complicated workflows increase cost and slow deployment

Engineering Contradiction:
Improvediagnostic capabilityVSAvoidworkflow complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent resolves this contradiction by modifying probe temperature parameters to reduce probe effects on amplification. This improvement in amplification efficiency allows for more comprehensive diagnostic testing with reduced reagent consumption and simplified workflows, thereby increasing adaptability while decreasing complexity and cost.

Inventive Principle:
Principle #35Parameter changes

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 approach enhances the detection of nucleic acid targets, improves analytical sensitivity, and simplifies workflows, making qPCR more deployable and cost-effective for clinical diagnostics by minimizing instrument variability and inhibitor interference.

Implementation Method 1

the nucleic acid probe hybridizes to the target nucleic acid molecule and has a probe: template melting temperature less than the denaturation temperature, the annealing temperature, and the extension temperature used in a polymerase chain reaction (PCR) amplification cycle

Methodology Applied
Scientific EffectHybridization: Chemical Bonding

Implementation Method 2

polymerase chain reaction (PCR) amplification cycle

Methodology Applied
Scientific EffectPolymerase chain reaction: Enzyme

Implementation Method 3

the nucleic acid probe is fluorogenic. In various embodiments of any of the aspects delineated herein, fluorescence is used to generate a melting curve

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 4

a chemical denaturant is used to increase the ΔTm between the annealing temperature and the probe Tm

Methodology Applied
Scientific EffectChemical denaturation:

Data Source

PatentEP2766501B1Quantitative nucleic acid amplification
Publication Date: 2020.01.01 ACCUGENOMICS
  • EP2766501B1 patent drawingFigure 1
  • EP2766501B1 patent drawingFigure 2
  • EP2766501B1 patent drawingFigure 3A~3B

AI summary

The invention features compositions and methods that are useful for the measurement of the quantity of a nucleic acid target in a sample.