Direct Nucleic Acid Amplification Without Extraction for Pathogen Detection
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Solution Overview
Problem
Current methods for detecting viral and bacterial pathogens, such as RT-PCR, are time-consuming and expensive, requiring complex steps like nucleic acid extraction and purification, which hinder rapid diagnosis.
Innovation Solution
A reagent mixture that allows for direct amplification of nucleic acids from biological samples without prior extraction, using DNA polymerase, buffer, and optional reverse transcriptase, with components like KCl, surfactants, and heat to enhance lysis and inhibit amplification inhibitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RT-PCR or standard PCR methods are used for pathogen detection, then sensitivity and specificity are improved, but the complexity of the procedure and time required increase due to nucleic acid extraction and purification steps
Solution Approach 1:
The patent combines the nucleic acid extraction, purification, and amplification steps into a single integrated reaction system. The buffer composition includes components that simultaneously perform cell lysis, nucleic acid purification, and PCR amplification, eliminating the need for separate extraction and purification steps while maintaining detection sensitivity.
Solution Approach 2:
The buffer system is designed to perform multiple functions: it acts as a lysis buffer to break down cells and release nucleic acids, a purification buffer to remove inhibitors and isolate nucleic acids, and a PCR buffer to support amplification. This multi-functional buffer replaces multiple separate reagents and steps.
2Reliability
If nucleic acid extraction and purification steps are performed, then amplification quality is improved, but the time required for diagnosis increases
Solution Approach 1:
The buffer contains pre-formulated components that perform extraction and purification actions during the initial stages of the reaction, before amplification begins. The lysis and purification processes are initiated simultaneously with the amplification setup, eliminating sequential waiting time.
Solution Approach 2:
The reaction proceeds continuously without interruption or intermediate steps. The lysis, purification, and amplification processes overlap in time, with the buffer maintaining optimal conditions for each process simultaneously, eliminating idle time between steps.
3Measurement precision
If traditional PCR methods are used, then detection accuracy is improved, but the cost and technical requirements increase
Solution Approach 1:
The patent uses a disposable, pre-formulated buffer system that can be directly added to samples without requiring complex equipment or specialized technical skills for preparation. The buffer is designed as a ready-to-use reagent that simplifies the workflow and reduces technical barriers.
Solution Approach 2:
The buffer acts as an intermediary that mediates between the crude sample and the amplification reaction. It contains components that neutralize inhibitors, protect nucleic acids, and create optimal reaction conditions, bridging the gap between simple sample collection and accurate detection.
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
Enables rapid and sensitive detection of pathogens like influenza and C. difficile with equivalent or improved sensitivity compared to traditional methods, reducing the need for nucleic acid extraction and purification steps.
Implementation Method 1
contacting the sample with a DNA polymerase and a buffer under conditions suitable for amplification of the target nucleic acid from the sample
Implementation Method 2
The dsDNA is then denaturized at about 95°C, so that the two strands separate
Implementation Method 3
an RNA strand is first reverse transcribed into its DNA complement (cDNA) using the enzyme reverse transcriptase
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Provided herein are methods for identifying the presence or absence of a target nucleic acid from a microorganism using direct amplification without a step of extraction of the nucleic acids, but retaining substantially the same specificity and sensitivity of methods assaying extracted nucleic acids.