Nucleic Acid Amplification Bias Reduction via Modified Nucleotides
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nucleic acid amplification methods, such as PCR, suffer from sequence-specific biases, particularly in multiplex reactions, leading to uneven amplification of AT-rich and GC-rich sequences, which results in inaccurate sequence representation and increased costs due to the need for higher coverage and more extensive sequencing.
Innovation Solution
The method involves adjusting nucleotide concentrations and using nucleotide analogues to normalize amplification efficiencies, specifically by reducing AT-rich sequence amplification and enhancing GC-rich sequence amplification, thereby achieving balanced cluster sizes and intensities on solid supports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard PCR amplification is used, then amplification speed and productivity are improved, but sequence-specific bias occurs leading to unequal representation of different sequence types
Solution Approach 1:
The patent modifies the chemical parameters of the amplification reaction by incorporating modified nucleotides (such as dUTP, dITP, or other non-canonical nucleotides) in place of standard dNTPs. These modified nucleotides change the polymerase incorporation kinetics and cluster formation characteristics, thereby reducing sequence-specific bias while maintaining amplification efficiency. The modified nucleotides alter the biochemical parameters of the reaction to achieve more uniform amplification across different sequence compositions.
2Manufacturing precision
If higher coverage sequencing is performed to compensate for bias, then sequence representation accuracy is improved, but sequencing costs and time increase
Solution Approach 1:
The patent applies modified nucleotides during the amplification step to preemptively correct sequence-specific bias before sequencing occurs. By modifying the nucleotide incorporation during cluster generation, the method ensures more uniform representation of different sequence types in the initial amplification products, eliminating the need for subsequent over-sequencing to compensate for under-represented regions. This preliminary correction at the amplification stage reduces the total sequencing depth required.
3Productivity
If AT-rich sequences are amplified more efficiently, then amplification productivity is improved, but GC-rich sequences become under-represented
Solution Approach 1:
The patent introduces modified nucleotides as intermediaries that mediate the polymerase reaction to achieve more balanced amplification. These modified nucleotides (e.g., dUTP, dITP, or other analogs) serve as intermediaries that alter the polymerase's interaction with the template, reducing the inherent bias toward AT-rich sequences. The modified nucleotides act as a buffering mechanism that equalizes incorporation rates across different sequence compositions, ensuring GC-rich sequences are adequately represented.
4Productivity
If cluster density is increased on solid support, then productivity is improved, but sequence-specific bias in cluster size increases
Solution Approach 1:
The patent modifies the nucleotide incorporation parameters by using modified nucleotides that change the kinetics and efficiency of cluster formation. These modified nucleotides alter the amplification dynamics to produce more uniform cluster sizes even at high densities. The chemical modification of nucleotides affects the polymerase extension rate and cluster growth characteristics, thereby reducing size variation among clusters of different sequence compositions while maintaining high productivity.
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 reduces sequence-specific biases, ensuring more equal representation of AT-rich and GC-rich sequences, leading to improved sequencing accuracy and reduced costs by maintaining polymerase fidelity and increasing cluster density without over-amplifying certain sequences.
Implementation Method 1
The PCR reaction is a DNA synthesis reaction that depends on the extension of the forward and reverse primers annealed to opposite strands of a dsDNA template
Implementation Method 2
a molar excess of a forward and reverse primer which bind to the target nucleic acid molecule
Implementation Method 3
a dsDNA template that has been denatured (melted apart) at high temperature (90° C. to 100° C.)
Data Source
AI summary
Methods for amplifying nucleic acids are provided. The methods can be used to minimize sequence specific bias caused by the preferential amplification of certain nucleic acid sequences. Methods are described which can lower the efficiency of AT rich templates relative to GC rich templates, thereby minimizing GC bias during amplification reactions with multiple templates of different sequence. The methods are suited to solid phase amplification, for example, utilizing flow cells.