RNA-DNA Chimeric Primers for PCR Specificity
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Solution Overview
Problem
DNA-dependent DNA polymerase amplification reactions, such as PCR and qPCR, suffer from non-specific amplification products like primer dimers and probe dimers due to weak interactions, leading to reduced sensitivity and specificity, especially in multiplex reactions and High Resolution Melt analysis, where these artifacts mask target sequences and complicate interpretation.
Innovation Solution
Incorporating ribonucleotides into DNA primers and probes in a non-random manner, scattered along their length, creates RNA/DNA chimeric molecules that impede the initiation of DNA synthesis at sites with RNA modifications while allowing elongation beyond these sites, thereby reducing non-specific amplification products without requiring special enzymatic or chemical manipulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard DNA primers are used in PCR amplification reactions, then amplification efficiency is maintained, but non-specific amplification products such as primer dimers and probe dimers form due to weak interactions between primers or primers and probes
Solution Approach 1:
The patent applies local quality by modifying only specific positions within the primer sequence (positions 3-10 from the 5' end) with ribonucleotides, while leaving other positions as standard deoxyribonucleotides. This localized modification approach prevents non-specific amplification products at critical regions while maintaining overall primer functionality and amplification efficiency.
Solution Approach 2:
The patent creates composite primers consisting of both ribonucleotides and deoxyribonucleotides within the same oligonucleotide sequence. This composite structure combines the benefits of RNA (reduced non-specific binding) and DNA (stable hybridization and efficient amplification) to eliminate primer dimers while maintaining target-specific amplification.
2Object-generated harmful factors
If careful primer design and stringent PCR protocols are used to reduce non-specific amplification products, then primer dimer formation is reduced, but the complexity of the PCR protocol increases
Solution Approach 1:
The patent changes the chemical composition parameter of the primer by incorporating ribonucleotides at specific positions, which inherently reduces non-specific binding affinity. This parameter change eliminates the need for complex protocol modifications such as extended annealing times or multiple temperature steps, simplifying the overall PCR protocol while effectively reducing primer dimer formation.
3Object-generated harmful factors
If modified nucleotides are used at the 3' end of primers to reduce non-specific amplification products, then primer dimer formation is reduced, but amplification efficiency may be compromised
Solution Approach 1:
The patent applies local quality by strategically placing ribonucleotides at positions 3-10 from the 5' end, which are not at the 3' terminus. This localized modification reduces non-specific binding in regions prone to dimer formation while preserving the 3' end functionality for efficient DNA polymerase extension and maintaining high amplification efficiency.
Solution Approach 2:
The patent uses partial action by incorporating ribonucleotides at only 1-5 specific positions within the primer sequence rather than modifying the entire primer or using excessive modifications. This partial modification approach is sufficient to prevent non-specific amplification products while avoiding over-modification that could interfere with primer function and amplification efficiency.
Data Source
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AI summary
Methods are provided for amplification of a nucleic acid sequence. The method use RNA/DNA chimeric oligonucleotides as primers. The primers have RNA residues scattered along their length and no two ribonucleotides in the prime are adjacent to one another. The methods are useful for reducing non-specific amplification products, such as primer dimers. The invention also provides kits comprising RNA/DNA chimeric oligonucleotide primers for practicing the amplification methods.