scholarly journals Microfluidic Chip with Two-Stage Isothermal Amplification Method for Highly Sensitive Parallel Detection of SARS-CoV-2 and Measles Virus

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1582
Author(s):  
Qin Huang ◽  
Xiaohui Shan ◽  
Ranran Cao ◽  
Xiangyu Jin ◽  
Xue Lin ◽  
...  
Keyword(s):  
Microfluidic Chip ◽  
Measles Virus ◽  
Point Of Care ◽  
Isothermal Amplification ◽  
Molecular Diagnostic ◽  
Nasopharyngeal Swab ◽  
Two Stage ◽  
Parallel Detection ◽  
Amplification Method ◽  
Specificity And Sensitivity

A two-stage isothermal amplification method, which consists of a first-stage basic recombinase polymerase amplification (RPA) and a second-stage fluorescence loop-mediated isothermal amplification (LAMP), as well as a microfluidic-chip-based portable system, were developed in this study; these enabled parallel detection of multiplex targets in real time in around one hour, with high sensitivity and specificity, without cross-contamination. The consumption of the sample and the reagent was 2.1 μL and 10.6 μL per reaction for RPA and LAMP, respectively. The lowest detection limit (LOD) was about 10 copies. The clinical amplification of about 40 nasopharyngeal swab samples, containing 17 SARS-CoV-2 (severe acute respiratory syndrome coronavirus) and 23 measles viruses (MV), were parallel tested by using the microfluidic chip. Both clinical specificity and sensitivity were 100% for MV, and the clinical specificity and sensitivity were 94.12% and 95.83% for SARS-CoV-2, respectively. This two-stage isothermal amplification method based on the microfluidic chip format offers a convenient, clinically parallel molecular diagnostic method, which can identify different nucleic acid samples simultaneously and in a timely manner, and with a low cost of the reaction reagent. It is especially suitable for resource-limited areas and point-of-care testing (POCT).

scholarly journals Microfluidic Chip-Based Detection and Intraspecies Strain Discrimination of Salmonella Serovars Derived from Whole Blood of Septic Mice

2013 ◽  
Vol 79 (7) ◽  
pp. 2302-2311 ◽  
Author(s):  
Adriana S. Patterson ◽  
Douglas M. Heithoff ◽  
Brian S. Ferguson ◽  
H. Tom Soh ◽  
Michael J. Mahan ◽  
...  
Keyword(s):  
Public Health ◽  
Microfluidic Chip ◽  
Whole Blood ◽  
Point Of Care ◽  
The United States ◽  
Isothermal Amplification ◽  
Microbial Pathogens ◽  
Content Type ◽  
Amplification Method ◽  
Single Temperature

ABSTRACTSalmonellais a zoonotic pathogen that poses a considerable public health and economic burden in the United States and worldwide. Resultant human diseases range from enterocolitis to bacteremia to sepsis and are acutely dependent on the particular serovar ofSalmonella entericasubsp.enterica, which comprises over 99% of human-pathogenicS. entericaisolates. Point-of-care methods for detection and strain discrimination ofSalmonellaserovars would thus have considerable benefit to medical, veterinary, and field applications that safeguard public health and reduce industry-associated losses. Here we describe a single, disposable microfluidic chip that supports isothermal amplification and sequence-specific detection and discrimination ofSalmonellaserovars derived from whole blood of septic mice. The integrated microfluidic electrochemical DNA (IMED) chip consists of an amplification chamber that supports loop-mediated isothermal amplification (LAMP), a rapid, single-temperature amplification method as an alternative to PCR that offers advantages in terms of sensitivity, reaction speed, and amplicon yield. The amplification chamber is connected via a microchannel to a detection chamber containing a reagentless, multiplexed (here biplex) sensing array for sequence-specific electrochemical DNA (E-DNA) detection of the LAMP products. Validation of the IMED device was assessed by the detection and discrimination ofS. entericasubsp.entericaserovars Typhimurium and Choleraesuis, the causative agents of enterocolitis and sepsis in humans, respectively. IMED chips conferred rapid (under 2 h) detection and discrimination of these strains at clinically relevant levels (<1,000 CFU/ml) from whole, unprocessed blood collected from septic animals. The IMED-based chip assay shows considerable promise as a rapid, inexpensive, and portable point-of-care diagnostic platform for the detection and strain-specific discrimination of microbial pathogens.

scholarly journals IsoPCR: An Analytically Sensitive, Nested, Multiplex Nucleic Acid Amplification Method

2013 ◽  
Vol 59 (2) ◽  
pp. 436-439 ◽  
Author(s):  
Martin Jensen Søe ◽  
Mikkel Rohde ◽  
Jens Mikkelsen ◽  
Peter Warthoe
Keyword(s):  
Nucleic Acid ◽  
Candida Glabrata ◽  
Simultaneous Detection ◽  
Lamp Assay ◽  
Isothermal Amplification ◽  
Qpcr Assay ◽  
Nucleic Acid Amplification ◽  
Molecular Diagnostic ◽  
Nucleic Acid Detection ◽  
Amplification Method

BACKGROUND Nucleic acid tests that can simultaneously detect multiple targets with high sensitivity, specificity, and speed are highly desirable. To meet this need, we developed a new approach we call the isoPCR method. METHODS The isoPCR method is a 2-stage nested-like nucleic acid amplification method that combines a single multiplex preamplification PCR with subsequent distinct detection of specific targets by use of isothermal amplification. We compared isoPCR to nested quantitative PCR (qPCR), loop-mediated isothermal amplification (LAMP), and nested LAMP (PCR followed by LAMP), for detection of DNA from Candida glabrata. We evaluated the method's multiplex capability for detecting low copy numbers of pathogens commonly involved in sepsis. RESULTS IsoPCR provided detection of 1 copy of Candida glabrata, an LOD that was 5-fold lower than a nested qPCR assay (5 copies), while the amplification time was simultaneously halved. Similarly, the LOD for isoPCR was lower than that for a LAMP assay (1000 copies) and a nested LAMP assay (5 copies). IsoPCR required recognition of 6 regions for detection, thereby providing a theoretically higher specificity compared to nested qPCR (4 regions). The isoPCR multiplexing capability was demonstrated by simultaneous detection of 4 pathogens with individual LODs of 10 copies or fewer. Furthermore, the specificity of isoPCR was demonstrated by successful pathogen detection from samples with more than 1 pathogen present. CONCLUSIONS IsoPCR provides a molecular diagnostic tool for multiplex nucleic acid detection, with an LOD down to 1 copy, high theoretical specificity, and halving of the amplification time compared to a nested qPCR assay.

scholarly journals Multiplex logic processing isothermal diagnostic assays for an evolving virus

2018 ◽  
Author(s):  
Sanchita Bhadra ◽  
Miguel A. Saldaña ◽  
Hannah Grace Han ◽  
Grant L. Hughes ◽  
Andrew D. Ellington
Keyword(s):  
Point Of Care ◽  
Direct Analysis ◽  
Human Saliva ◽  
Ease Of Use ◽  
Molecular Diagnostic ◽  
One Pot ◽  
Diagnostic Assays ◽  
Specificity And Sensitivity ◽  
Isothermal Assay ◽  
Fail Safe

AbstractWe have developed a generalizable ‘smart molecular diagnostic’ capable of accurate point-of-care (POC) detection of variable nucleic acid targets. Our one-pot isothermal assay relies on multiplex execution of four loop-mediated isothermal amplification reactions, with primers that are degenerate and redundant, thereby increasing the breadth of targets while reducing the probability of amplification failure. An easy-to-read visual answer is computed directly by a multi-input Boolean OR gate signal transducer that uses degenerate strand exchange probes to assess any combination of amplicons. We demonstrate our platform by using the same assay to detect divergent Asian and African lineages of the evolving Zika virus (ZIKV), while maintaining selectivity against non-target viruses. Direct analysis of biological specimens proved possible, with 20 virions / µl being directly detected in human saliva within 90 minutes, and crudely macerated ZIKV-infected Aedes aegypti mosquitoes being identified with 100% specificity and sensitivity. The ease-of-use with minimal instrumentation, broad programmability, and built-in fail-safe reliability make our smart molecular diagnostic attractive for POC use.

scholarly journals An enhanced isothermal amplification assay for viral detection

2020 ◽  
Author(s):  
Jason Qian ◽  
Sarah A. Boswell ◽  
Christopher Chidley ◽  
Zhi-xiang Lu ◽  
Mary E. Pettit ◽  
...  
Keyword(s):  
Rna Isolation ◽  
Isothermal Amplification ◽  
Molecular Diagnostic ◽  
Nucleic Acid Detection ◽  
Sample Collection ◽  
Amplification Method ◽  
Current State ◽  
Highly Sensitive ◽  
Amplification Assay ◽  
Molecular Diagnostic Test

AbstractRapid, inexpensive, robust diagnostics are essential to control the spread of infectious diseases. Current state of the art diagnostics are highly sensitive and specific, but slow, and require expensive equipment. We developed a molecular diagnostic test for SARS-CoV-2, FIND (Fast Isothermal Nucleic acid Detection), based on an enhanced isothermal recombinase polymerase amplification reaction. FIND has a detection limit on patient samples close to that of RT-qPCR, requires minimal instrumentation, and is highly scalable and cheap. It can be performed in high throughput, does not cross-react with other common coronaviruses, avoids bottlenecks caused by the current worldwide shortage of RNA isolation kits, and takes ~45 minutes from sample collection to results. FIND can be adapted to future novel viruses in days once sequence is available.One sentence summarySensitive, specific, rapid, scalable, enhanced isothermal amplification method for detecting SARS-CoV-2 from patient samples.

scholarly journals Development of a dual-gene loop-mediated isothermal amplification (LAMP) detection assay for SARS-CoV-2: A preliminary study

2020 ◽  
Author(s):  
Azeem Mehmood Butt ◽  
Shafiqa Siddique ◽  
Xiaoping An ◽  
Yigang Tong
Keyword(s):  
Point Of Care ◽  
Lamp Assay ◽  
Cross Reactivity ◽  
Isothermal Amplification ◽  
Nasopharyngeal Swab ◽  
Loop Mediated Isothermal Amplification ◽  
Qualitative Detection ◽  
Detection Assay ◽  
Testing Protocols ◽  
Positive Results

AbstractSevere acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) has emerged as a rapidly spreading global pathogen stressing the need for development of rapid testing protocols ever than before. The aim of present study was to develop a SARS-CoV-2 detection protocol which can be performed within minimal resources and timeframe. For this purpose, we implemented the reverse transcription loop-mediated isothermal amplification (RT-LAMP) methodology for the qualitative detection of SARS-CoV-2 RNA. In order to improve the detection capability, the RT-LAMP assay was developed to simultaneously amplify two viral genes: ORF1a and N. A total of 45 SARS-CoV-2 associated coronavirus disease 2019 (COVID-19) and 25 non-COVID-19 cases were enrolled. Viral RNA was extracted from the nasopharyngeal swab samples and analyzed simultaneously using PCR and RT-LAMP protocols. Overall, our SARS-CoV-2 dual gene RT-LAMP assay was found to be 95% accurate in detecting positive cases and showed no cross-reactivity or false-positive results in non-COVID-19 samples. Further evaluation on larger and multi-centric cohorts is currently underway to establish the diagnostic accuracy and subsequent implementation into clinical practice and at point-of-care settings.

scholarly journals Fast and Parallel Detection of Four Ebola Virus Species on a Microfluidic-Chip-Based Portable Reverse Transcription Loop-Mediated Isothermal Amplification System

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 777 ◽  
Author(s):  
Xue Lin ◽  
Xiangyu Jin ◽  
Bin Xu ◽  
Ruliang Wang ◽  
Rongxin Fu ◽  
...  
Keyword(s):  
Microfluidic Chip ◽  
Reverse Transcription ◽  
Ebola Virus ◽  
Limit Of Detection ◽  
Isothermal Amplification ◽  
Diagnostic Methods ◽  
Virus Species ◽  
Fluorescence Detector ◽  
Parallel Detection ◽  
Loop Mediated Isothermal Amplification

Considering the lack of official vaccines and medicines for Ebola virus infection, reliable diagnostic methods are necessary for the control of the outbreak and the spread of the disease. We developed a microfluidic-chip-based portable system for fast and parallel detection of four Ebola virus species. The system is based on reverse transcription loop-mediated isothermal amplification (RT-LAMP) and consists of four specific LAMP primers, a disc microfluidic chip, and a portable real-time fluorescence detector. It could specifically and parallelly distinguish four species of the Ebola virus after only one sampling, including the Zaire Ebola virus, the Sudan Ebola virus, the Bundibugyo Ebola virus, and the Tai Forest Ebola virus, without cross-contamination. The limit of detection was as small as 10 copies per reaction, while the total consumption of sample and reagent was 0.94 μL per reaction. The final results could be obtained in 50 min after one addition of sample and reagent mixture. This approach provides simplicity, high sensitivity, and multi-target parallel detection at a low cost, which could enable convenient and effective on-site detections of the Ebola virus in the outdoors, remote areas, and modern hospitals.

scholarly journals Simultaneous Detection of Different Zika Virus Lineages via Molecular Computation in a Point-of-Care Assay

Viruses ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 714 ◽  
Author(s):  
Sanchita Bhadra ◽  
Miguel Saldaña ◽  
Hannah Han ◽  
Grant Hughes ◽  
Andrew Ellington
Keyword(s):  
Zika Virus ◽  
Point Of Care ◽  
Logic Gate ◽  
Simultaneous Detection ◽  
Direct Analysis ◽  
Ease Of Use ◽  
Molecular Diagnostic ◽  
Specificity And Sensitivity ◽  
Isothermal Assay ◽  
Fail Safe

We have developed a generalizable “smart molecular diagnostic” capable of accurate point-of-care (POC) detection of variable nucleic acid targets. Our isothermal assay relies on multiplex execution of four loop-mediated isothermal amplification reactions, with primers that are degenerate and redundant, thereby increasing the breadth of targets while reducing the probability of amplification failure. An easy-to-read visual answer is computed directly by a multi-input Boolean OR logic gate (gate output is true if either one or more gate inputs is true) signal transducer that uses degenerate strand exchange probes to assess any combination of amplicons. We demonstrate our methodology by using the same assay to detect divergent Asian and African lineages of the evolving Zika virus (ZIKV), while maintaining selectivity against non-target viruses. Direct analysis of biological specimens proved possible, with crudely macerated ZIKV-infected Aedes aegypti mosquitoes being identified with 100% specificity and sensitivity. The ease-of-use with minimal instrumentation, broad programmability, and built-in fail-safe reliability make our smart molecular diagnostic attractive for POC use.

scholarly journals Comparative Diagnostic Performance of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) Kit for the Rapid Detection of SARS-CoV-2

Pathogens ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1629
Author(s):  
Alexander Domnich ◽  
Andrea Orsi ◽  
Donatella Panatto ◽  
Vanessa De Pace ◽  
Valentina Ricucci ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Diagnostic Performance ◽  
Point Of Care ◽  
Lamp Assay ◽  
Laboratory Diagnosis ◽  
Isothermal Amplification ◽  
Molecular Diagnostic ◽  
Rt Pcr ◽  
Laboratory Equipment ◽  
Loop Mediated Isothermal Amplification

Although the reverse transcription-polymerase chain reaction (RT-PCR) is considered a standard-of-care assay for the laboratory diagnosis of SARS-CoV-2, several limitations of this method have been described. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) is an alternative molecular assay and is potentially able to overcome some intrinsic shortcomings of RT-PCR. In this study, we evaluated the diagnostic performance of the novel HG COVID-19 RT-LAMP assay. In this retrospective analysis, a total of 400 routinely collected leftover nasopharyngeal samples with a known RT-PCR result were tested by means of the HG COVID-19 RT-LAMP assay. The overall sensitivity and specificity values of HG COVID-19 RT-LAMP versus RT-PCR were 97.0% (95% CI: 93.6–98.9%) and 98.5% (95% CI: 95.7–99.7%), respectively. Inter-assay agreement was almost perfect (κ = 0.96). Concordance was perfect in samples with high viral loads (cycle threshold < 30). The average time to a positive result on RT-LAMP was 17 min. HG COVID-19 RT-LAMP is a reliable molecular diagnostic kit for detecting SARS-CoV-2, and its performance is comparable to that of RT-PCR. Shorter turnaround times and the possibility of performing molecular diagnostics in the point-of-care setting make it a valuable option for facilities without sophisticated laboratory equipment.

scholarly journals iSCAN: An RT-LAMP-coupled CRISPR-Cas12 module for rapid, sensitive detection of SARS-CoV-2

2020 ◽  
Author(s):  
Zahir Ali ◽  
Rashid Aman ◽  
Ahmed Mahas ◽  
Gundra Sivakrishna Rao ◽  
Muhammad Tehseen ◽  
...  
Keyword(s):  
Point Of Care ◽  
Human Life ◽  
Virus Detection ◽  
Turnaround Time ◽  
Nucleic Acid Amplification ◽  
Molecular Diagnostic ◽  
Amplification Method ◽  
Single Temperature ◽  
User Friendly ◽  
And Control

AbstractThe COVID-19 pandemic caused by SARS-CoV-2 affects all aspects of human life. Detection platforms that are efficient, rapid, accurate, specific, sensitive, and user friendly are urgently needed to manage and control the spread of SARS-CoV-2. RT-qPCR based methods are the gold standard for SARS-CoV-2 detection. However, these methods require trained personnel, sophisticated infrastructure, and a long turnaround time, thereby limiting their usefulness. Reverse transcription-loop-mediated isothermal amplification (RT-LAMP), a one-step nucleic acid amplification method conducted at a single temperature, has been used for colorimetric virus detection. CRISPR-Cas12 and CRISPR-Cas13 systems, which possess collateral activity against ssDNA and RNA, respectively, have also been harnessed for virus detection. Here, we built an efficient, rapid, specific, sensitive, user-friendly SARS-CoV-2 detection module that combines the robust virus amplification of RT-LAMP with the specific detection ability of SARS-CoV-2 by CRISPR-Cas12. Furthermore, we combined the RT-LAMP-CRISPR-Cas12 module with lateral flow cells to enable highly efficient point-of-care SARS-CoV-2 detection. Our iSCAN SARS-CoV-2 detection module, which exhibits the critical features of a robust molecular diagnostic device, should facilitate the effective management and control of COVID-19.

scholarly journals A Novel Isothermal Amplification Method for Detecting Mouse Source Component in Meat

2019 ◽  
Vol 102 (3) ◽  
pp. 872-877 ◽  
Author(s):  
Xinnan Li ◽  
Xueqin Gao ◽  
Yifu Guan
Keyword(s):  
Isothermal Amplification ◽  
New Method ◽  
Simple Method ◽  
New Approach ◽  
Safety Issues ◽  
Amplification Method ◽  
Specificity And Sensitivity ◽  
Great Specificity ◽  
Nonspecific Amplification ◽  
Dna Template

Abstract Background: The problem of adulterated meat has become one of the greatest food safety issues in the world. It is reported that the meat used for adulteration includes fox meat, raccoon meat, mink meat, mouse meat, and so on. Although this kind of meat is edible in some areas, such meat is potentially harmful to human health because it is easy to carry bacteria, viruses, and harmful substances. The harm of mouse meat is most frightening. Therefore, it is urgent to develop a fast, accurate, and simple method to effectively identify mouse meat. Methods: In the present study, a new method of isothermal amplification based on the 16S ribosomal RNA gene of the mitochondrial DNA of the mouse was developed. The method is meant to improve the loop-mediated isothermal amplification (LAMP), separating the forward inner primers and backward inner primers, greatly reducing the nonspecific amplification of the method. Results: We have successfully obtained a set of best primers. The developed system allowed for the detection of 0.5% mouse meat from meat mixture effectively and specifically. The best ratio of the primers (F3: F2: F1: RF) was 1:2:2:8, and the optimum concentration of DNA template was 0.35 ng/μL. Conclusions: The assay has great specificity and sensitivity for detecting mouse meat and could provide specific positive results within 1 h. Highlights: We found a new approach of isothermal amplification to detect mouse source components. The LOD is determined to be 0.5 mg/mg. This new method is easy to perform and is able to provide rapid results in the specific detection of mouse meat sources.

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