Nested Fluorescent Microarray for Low Viral Load Detection
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Solution Overview
Problem
Current COVID-19 diagnostic methods, particularly Q-RT-PCR, face challenges with high false negative rates, especially at low viral loads, and are inefficient for early detection of asymptomatic carriers, necessitating the development of more sensitive and specific tools for respiratory virus detection across diverse sampling locations.
Innovation Solution
A method involving RNA isolation from samples, followed by amplification using fluorescent labeled primers and hybridization to nucleic acid probes on a microarray, allowing for the detection of COVID-19 and other respiratory pathogens with enhanced sensitivity and specificity, capable of distinguishing between positive and negative signals near the lowest limit of detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Q-RT-PCR is used for COVID-19 detection, then the method is widely adopted and standardized, but the false negative rate increases to 15-30% especially at low viral loads
Solution Approach 1:
The patent segments the detection process into two distinct amplification stages: first amplification generates initial amplicons from viral RNA, and second amplification generates fluorescently labeled amplicons from the first amplicons. This segmentation allows cumulative amplification across stages, achieving detection sensitivity at 10^-6 to 10^-9 molar concentrations, far exceeding single-stage PCR capabilities and eliminating false negatives at low viral loads.
Solution Approach 2:
The patent implements nested amplification where the second amplification reaction is performed using amplicons from the first amplification as templates. This nested structure enables exponential amplification of the original viral RNA signal through multiple generations, providing the sensitivity needed to detect asymptomatic carriers with minimal viral RNA while maintaining the reliability of standardized PCR methodology.
2Measurement precision
If standard PCR amplification is used, then the process is simple and quick, but the detection sensitivity is insufficient for early detection of asymptomatic carriers
Solution Approach 1:
The first amplification reaction serves as a preliminary action that generates sufficient amplicon templates before the second amplification stage. This preliminary amplification ensures that even trace amounts of viral RNA are amplified to detectable levels in the first stage, enabling the second stage to further amplify these signals with fluorescent labeling, thereby achieving ultra-sensitive detection without overwhelming system complexity.
Solution Approach 2:
The first amplicons act as intermediaries between the original viral RNA and the final fluorescently labeled detection products. These intermediate amplicons bridge the two amplification stages, allowing the system to accumulate amplification power across stages while maintaining manageable reaction conditions at each step, thus achieving high sensitivity without excessive complexity.
3Adaptability or versatility
If multiple respiratory pathogens need to be detected simultaneously, then comprehensive diagnostic coverage is achieved, but the test complexity and resource requirements increase
Solution Approach 1:
The patent employs universal primers and probes that can detect multiple respiratory pathogens including SARS-CoV-2, influenza A, influenza B, and other coronaviruses within a single amplification system. The first amplification uses universal primers targeting conserved regions, while the second amplification uses pathogen-specific fluorescently labeled probes, enabling one system to perform multiple diagnostic functions simultaneously without requiring separate tests for each pathogen.
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 significantly reduces false negative rates, enables early detection of low viral loads, and allows for simultaneous detection of multiple respiratory pathogens, improving diagnostic accuracy and scalability for large-scale screening.
Implementation Method 1
at least one fluorescent labeled primer pair selective for COVID-19 virus RNA to generate fluorescent labeled COVID-19 virus specific amplicons
Implementation Method 2
These amplicons are hybridized to a plurality of nucleic acid probes, each attached at specific positions on a solid microarray support. The sequence of the nucleic acid probes corresponds to a sequence determinant in the COVID-19 virus RNA.
Data Source
AI summary
Provided herein is a method for detecting the presence of a COVID-19 virus in a human sample or an environmental sample having one or more viral and bacterial pathogens. Samples processed to obtain total nucleic acids. The nucleic acids are used as a template in a reverse transcription-amplification reaction to obtain cDNA, which is used in a PCR amplification reaction to obtain fluorescent COVID-19 virus specific amplicons. These amplicons are detected by microarray hybridization near the lowest limit of detection. Also provided is a method for detecting in addition to the COVID-19 virus, the presence of respiratory disease-causing pathogens including viruses, bacteria and fungus in a single assay using the above method.