scholarly journals Highly performing point-of-care molecular testing for SARS-CoV-2 with RNA extraction and isothermal amplification.

2020 ◽  
Author(s):  
Pierre Garneret ◽  
Etienne Coz ◽  
Elian Martin ◽  
Jean-Claude Manuguerra ◽  
Elodie Brient-Litzler ◽  
...  
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Rna Extraction ◽  
Dna Amplification ◽  
Developed Countries ◽  
Temperature Cycling ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Molecular Testing

In order to respond to the urgent request of massive testing, developed countries perform nucleic acid amplification tests (NAAT) of SARS-CoV-2 in centralized laboratories. Real-time RT - PCR (Reverse transcription - Polymerase Chain Reaction) is used to amplify the viral RNA and enable its detection. Although PCR is 37 years old, it is still considered, without dispute, as the gold standard. PCR is an efficient process, but the complex engineering required for automated RNA extraction and temperature cycling makes it incompatible for use in point of care settings. In the present work, by harnessing progress made in the past two decades in DNA amplification, microfluidics and membrane technologies, we succeeded to create a portable test, in which SARS-CoV-2 RNA is extracted, amplified isothermally by RT - LAMP (Loop-mediated Isothermal Amplification), and detected using intercalating dyes or highly fluorescent probes. Depending on the viral load, the detection takes between twenty minutes and one hour. Using pools of naso-pharyngal clinical samples, we estimated a sensitivity comparable to RT-qPCR (up to a Cycle threshold of 39, equivalent to <0.1 TCID50 per mL) and a 100% specificity, for other human coronaviruses and eight respiratory viruses currently circulating in Europe. We designed and fabricated an easy-to-use portable device called COVIDISC to carry out the test at the point of care. The low cost of the materials along with the absence of complex equipment paves the way towards a large dissemination of this device. The perspective of a reliable SARS-CoV-2 point of care detection, highly performing, that would deliver on-site results in less than one hour opens up a new efficient approach to manage the pandemics.

scholarly journals Performing point-of-care molecular testing for SARS-CoV-2 with RNA extraction and isothermal amplification

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0243712
Author(s):  
Pierre Garneret ◽  
Etienne Coz ◽  
Elian Martin ◽  
Jean-Claude Manuguerra ◽  
Elodie Brient-Litzler ◽  
...  
Keyword(s):  
Real Time ◽  
Limit Of Detection ◽  
Clinical Sample ◽  
Point Of Care ◽  
Rna Extraction ◽  
Temperature Cycling ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Molecular Testing ◽  
Rt Pcr

To respond to the urgent need for COVID-19 testing, countries perform nucleic acid amplification tests (NAAT) for the detection of SARS-CoV-2 in centralized laboratories. Real-time RT—PCR (Reverse transcription—Polymerase Chain Reaction), used to amplify and detect the viral RNA., is considered, as the current gold standard for diagnostics. It is an efficient process, but the complex engineering required for automated RNA extraction and temperature cycling makes it incompatible for use in point of care settings [1]. In the present work, by harnessing progress made in the past two decades in isothermal amplification and paper microfluidics, we created a portable test, in which SARS-CoV-2 RNA is extracted, amplified isothermally by RT—LAMP (Loop-mediated Isothermal Amplification), and detected using intercalating dyes or fluorescent probes. Depending on the viral load in the tested samples, the detection takes between twenty minutes and one hour. Using a set of 16 pools of naso-pharyngal swab eluates, we estimated a limit of detection comparable to real-time RT-PCR (i.e. 1 genome copies per microliter of clinical sample) and no cross‐reaction with eight major respiratory viruses currently circulating in Europe. We designed and fabricated an easy-to-use portable device called “COVIDISC” to carry out the test at the point of care. The low cost of the materials along with the absence of complex equipment will expedite the widespread dissemination of this device. What is proposed here is a new efficient tool to help managing the pandemics.

scholarly journals Loop Mediated Isothermal Amplification: Principles and Applications in Plant Virology

Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 461 ◽  
Author(s):  
Stefano Panno ◽  
Slavica Matić ◽  
Antonio Tiberini ◽  
Andrea Giovanni Caruso ◽  
Patrizia Bella ◽  
...  
Keyword(s):  
Plant Protection ◽  
Point Of Care ◽  
Low Cost ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Plant Virology ◽  
Food Industries ◽  
Loop Mediated Isothermal Amplification ◽  
Application Fields ◽  
Agriculture And Food

In the last decades, the evolution of molecular diagnosis methods has generated different advanced tools, like loop-mediated isothermal amplification (LAMP). Currently, it is a well-established technique, applied in different fields, such as the medicine, agriculture, and food industries, owing to its simplicity, specificity, rapidity, and low-cost efforts. LAMP is a nucleic acid amplification under isothermal conditions, which is highly compatible with point-of-care (POC) analysis and has the potential to improve the diagnosis in plant protection. The great advantages of LAMP have led to several upgrades in order to implement the technique. In this review, the authors provide an overview reporting in detail the different LAMP steps, focusing on designing and main characteristics of the primer set, different methods of result visualization, evolution and different application fields, reporting in detail LAMP application in plant virology, and the main advantages of the use of this technique.

scholarly journals Direct diagnostic testing of SARS-CoV-2 without the need for prior RNA extraction

2020 ◽  
Author(s):  
Shan Wei ◽  
Esther Kohl ◽  
Alexandre Djandji ◽  
Stephanie Morgan ◽  
Susan Whittier ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Diagnostic Testing ◽  
Rna Extraction ◽  
Nucleic Acid Amplification ◽  
Nasopharyngeal Swab ◽  
Viral Transport ◽  
Extraction Step ◽  
Highly Sensitive

AbstractThe COVID-19 pandemic has resulted in an urgent global need for rapid, point-of-care diagnostic testing. Existing methods for nucleic acid amplification testing (NAAT) require an RNA extraction step prior to amplification of the viral RNA. This step necessitates the use of a centralized laboratory or complex and costly proprietary cartridges and equipment, and thereby prevents low-cost, scalable, point-of-care testing. We report the development of a highly sensitive and robust, easy-to-implement, SARS-CoV-2 test that utilizes isothermal amplification and can be run directly on viral transport media following a nasopharyngeal swab without the need for prior RNA extraction. Our assay provides visual results in 30 min with 85% sensitivity, 100% specificity, and a limit of detection (LoD) of 2.5 copies/μl, and can be run using a simple heat block.

scholarly journals Detection of SARS-CoV-2 RNA by a Multiplex Reverse-Transcription Loop-Mediated Isothermal Amplification Coupled with Melting Curves Analysis

2021 ◽  
Vol 22 (11) ◽  
pp. 5743
Author(s):  
Igor P. Oscorbin ◽  
Georgiy Yu. Shevelev ◽  
Ksenia A. Pronyaeva ◽  
Andrey A. Stepanov ◽  
Darya V. Shamovskaya ◽  
...  
Keyword(s):  
Internal Control ◽  
Reverse Transcription ◽  
Control Sample ◽  
Dna Amplification ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Single Tube ◽  
Loop Mediated Isothermal Amplification ◽  
Amplification Process

Loop-mediated isothermal amplification (LAMP) is a method of nucleic acid amplification that is more stable and resistant to DNA amplification inhibitors than conventional PCR. LAMP multiplexing with reverse transcription allows for the single-tube amplification of several RNA fragments, including an internal control sample, which provides the option of controlling all analytical steps. We developed a method of SARS-CoV-2 viral RNA detection based on multiplex reverse-transcription LAMP, with single-tube qualitative analysis of SARS-CoV-2 RNA and MS2 phage used as a control RNA. The multiplexing is based on the differences in characteristic melting peaks generated during the amplification process. The developed technique detects at least 20 copies of SARS-CoV-2 RNA per reaction on a background of 12,000 MS2 RNA copies. The total time of analysis does not exceed 40 min. The method validation, performed on 125 clinical samples of patients’ nasal swabs, showed a 97.6% concordance rate with the results of real-time (RT)-PCR assays. The developed multiplexed LAMP can be employed as an alternative to PCR in diagnostic practice to save personnel and equipment time.

scholarly journals Isothermal Amplification of Nucleic Acids: The Race for the Next “Gold Standard”

2021 ◽  
Vol 2 ◽  
Author(s):  
Beatriz B. Oliveira ◽  
Bruno Veigas ◽  
Pedro Viana Baptista
Keyword(s):  
High Throughput ◽  
Gold Standard ◽  
Dna Amplification ◽  
Standard Technique ◽  
Isothermal Amplification ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
High Throughput Analysis ◽  
Throughput Analysis

Nucleic acid amplification technologies (NAATs) have become fundamental tools in molecular diagnostics, due to their ability to detect small amounts of target molecules. Since its development, Polymerase Chain Reaction (PCR) has been the most exploited method, being stablished as the “gold standard” technique for DNA amplification. However, the requirement for different working temperatures leads to the need of a thermocycler machine or complex thermal apparatus, which have been preventing its application in novel integrated devices for single workflow and high throughput analysis. Conversely, isothermal amplification methods have been gaining attention, especially for point-of-care diagnosis and applications. These non-PCR based methods have been developed by mimicking the in vivo amplification mechanisms, while performing the amplification with high sensitivity, selectivity and allowing for high-throughput analysis. These favorable capabilities have pushed forward the implementation and commercialization of several platforms that exploit isothermal amplification methods, mostly against virus, bacteria and other pathogens in water, food, environmental and clinical samples. Nevertheless, the future of isothermal amplification methods is still dependent on achieving technical maturity and broader commercialization of enzymes and reagents.

scholarly journals Developing a Low-Cost, Simple-to-Use Electrochemical Sensor for the Detection of Circulating Tumour DNA in Human Fluids

Biosensors ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 156
Author(s):  
Bukola Attoye ◽  
Chantevy Pou ◽  
Ewen Blair ◽  
Christopher Rinaldi ◽  
Fiona Thomson ◽  
...  
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Dna Amplification ◽  
Response To Therapy ◽  
Clinical Samples ◽  
Wild Type ◽  
Point Of Care Test ◽  
Improved Outcomes ◽  
Circulating Tumour Dna ◽  
Amplification Reaction

It is well-known that two major issues, preventing improved outcomes from cancer are late diagnosis and the evolution of drug resistance during chemotherapy, therefore technologies that address these issues can have a transformative effect on healthcare workflows. In this work we present a simple, low-cost DNA biosensor that was developed specifically to detect mutations in a key oncogene (KRAS). The sensor employed was a screen-printed array of carbon electrodes, used to perform parallel measurements of DNA hybridisation. A DNA amplification reaction was developed with primers for mutant and wild type KRAS sequences which amplified target sequences from representative clinical samples to detectable levels in as few as twenty cycles. High levels of sensitivity were demonstrated alongside a clear exemplar of assay specificity by showing the mutant KRAS sequence was detectable against a significant background of wild type DNA following amplification and hybridisation on the sensor surface. The time to result was found to be 3.5 h with considerable potential for optimisation through assay integration. This quick and versatile biosensor has the potential to be deployed in a low-cost, point-of-care test where patients can be screened either for early diagnosis purposes or monitoring of response to therapy.

scholarly journals Visual and Rapid Diagnosis of Neisseria gonorrhoeae Using Loop-Mediated Isothermal Amplification Combined With a Polymer Nanoparticle–Based Biosensor in Clinical Application

2021 ◽  
Vol 8 ◽  
Author(s):  
Xu Chen ◽  
Qingxue Zhou ◽  
Xueli Wu ◽  
Shuoshi Wang ◽  
Rui Liu ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Point Of Care ◽  
Low Cost ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Global Public Health ◽  
Fixed Temperature ◽  
Polymer Nanoparticle ◽  
Loop Mediated Isothermal Amplification

Neisseriagonorrhoeae is a host-adapted human pathogen that causes sexually transmitted gonorrhea and remains to be a serious global public health challenge, especially in low- and middle-income regions. It is vital to devise a reliable, simple, cost-saving, and easy-to-use assay for detecting the N. gonorrhoeae agent. In the current study, we firstly report a novel approach, loop-mediated isothermal amplification linked with a polymer nanoparticle–based biosensor (LAMP-PNB), that was used for identifying N. gonorrhoeae in clinical samples. The results showed that the LAMP primers based on the orf1 gene were valid for development of the N. gonorrhoeae-LAMP-PNB assay. The detection system with optimal conditions could be performed at a fixed temperature of 64°C for 40 min. The whole process, including genomic DNA preparation (approximately 10 min), LAMP reaction (40 min), and PNB reporting (approximately 2 min), could be accomplished within 60 min. The limit of detection (LoD) of the N. gonorrhoeae-LAMP-PNB assay was 50 copies per test. The specificity of the current assay was 100%, and no cross-reactions to non–N. gonorrhoeae isolates were observed. These results confirmed that the N. gonorrhoeae-LAMP-PNB technique is a reliable, specific, sensitive, rapid, low-cost, and easy-to-use method for detecting gonococci isolates. More importantly, this assay has great potential to develop a point-of-care (POC) testing method in clinical practice, especially in resource-constrained regions.

Clinical assessment of the Roche SARS-CoV-2 rapid antigen test

Diagnosis ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gian Luca Salvagno ◽  
Gianluca Gianfilippi ◽  
Damiano Bragantini ◽  
Brandon M. Henry ◽  
Giuseppe Lippi
Keyword(s):  
Clinical Assessment ◽  
Clinical Performance ◽  
Point Of Care ◽  
High Viral Load ◽  
Rapid Screening ◽  
Clinical Samples ◽  
Molecular Testing ◽  
Antigen Test ◽  
Community Screening ◽  
Final Study

Abstract Objectives Novel point-of-care antigen assays present a promising opportunity for rapid screening of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. The purpose of this study was the clinical assessment of the new Roche SARS-CoV-2 Rapid Antigen Test. Methods The clinical performance of Roche SARS-CoV-2 Rapid Antigen Test was evaluated vs. a reverse transcription polymerase chain reaction (RT-PCR) laboratory-based assay (Seegene AllplexTM2019-nCoV) in nasopharyngeal swabs collected from a series of consecutive patients referred for SARS-CoV-2 diagnostics to the Pederzoli Hospital (Peschiera del Garda, Verona, Italy) over a 2-week period. Results The final study population consisted of 321 consecutive patients (mean age, 46 years and IQR, 32–56 years; 181 women, 56.4%), with 149/321 (46.4%) positive for SARS-CoV-2 RNA via the Seegene AllplexTM2019-nCoV Assay, and 109/321 (34.0%) positive with Roche SARS-CoV-2 Rapid Antigen Test, respectively. The overall accuracy of Roche SARS-CoV-2 Rapid Antigen Test compared to molecular testing was 86.9%, with 72.5% sensitivity and 99.4% specificity. Progressive decline in performance was observed as cycle threshold (Ct) values of different SARS-CoV-2 gene targets increased. The sensitivity was found to range between 97–100% in clinical samples with Ct values <25, between 50–81% in those with Ct values between 25 and <30, but low as 12–18% in samples with Ct values between 30 and <37. Conclusions The clinical performance of Roche SARS-CoV-2 Rapid Antigen Test is excellent in nasopharyngeal swabs with Ct values <25, which makes it a reliable screening test in patients with high viral load. However, mass community screening would require the use of more sensitive techniques.

scholarly journals Direct diagnostic testing of SARS-CoV-2 without the need for prior RNA extraction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shan Wei ◽  
Esther Kohl ◽  
Alexandre Djandji ◽  
Stephanie Morgan ◽  
Susan Whittier ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Diagnostic Testing ◽  
Rna Extraction ◽  
Cost Effective ◽  
Clinical Samples ◽  
Nasopharyngeal Swab ◽  
Percentage Agreement ◽  
Testing Method ◽  
Viral Transport

AbstractThe COVID-19 pandemic has resulted in an urgent need for a rapid, point of care diagnostic testing that could be rapidly scaled on a worldwide level. We developed and tested a highly sensitive and robust assay based on reverse transcription loop mediated isothermal amplification (RT-LAMP) that uses readily available reagents and a simple heat block using contrived spike-in and actual clinical samples. RT-LAMP testing on RNA-spiked samples showed a limit of detection (LoD) of 2.5 copies/μl of viral transport media. RT-LAMP testing directly on clinical nasopharyngeal swab samples in viral transport media had an 85% positive percentage agreement (PPA) (17/20), and 100% negative percentage agreement (NPV) and delivered results in 30 min. Our optimized RT-LAMP based testing method is a scalable system that is sufficiently sensitive and robust to test for SARS-CoV-2 directly on clinical nasopharyngeal swab samples in viral transport media in 30 min at the point of care without the need for specialized or proprietary equipment or reagents. This cost-effective and efficient one-step testing method can be readily available for COVID-19 testing world-wide, especially in resource poor settings.

scholarly journals Essential properties and pitfalls of colorimetric Reverse Transcription Loop-mediated Isothermal Amplification as a point-of-care test for SARS-CoV-2 diagnosis

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Bruna de Oliveira Coelho ◽  
Heloisa Bruna Soligo Sanchuki ◽  
Dalila Luciola Zanette ◽  
Jeanine Marie Nardin ◽  
Hugo Manuel Paz Morales ◽  
...  
Keyword(s):  
Viral Load ◽  
Internal Control ◽  
Reverse Transcription ◽  
Color Change ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
False Negative ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Loop Mediated Isothermal Amplification

Abstract Background SARS-CoV-2 Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) colorimetric detection is a sensitive and specific point-of-care molecular biology technique used to detect the virus in only 30 min. In this manuscript we have described a few nuances of the technique still not properly described in the literature: the presence of three colors clusters; the correlation of the viral load with the color change; and the importance of using an internal control to avoid false-negative results. Methods To achieve these findings, we performed colorimetric RT-LAMP assays of 466 SARS-CoV-2 RT-qPCR validated clinical samples, with color quantification measured at 434 nm and 560 nm. Results First we determinate a sensitivity of 93.8% and specificity of 90.4%. In addition to the pink (negative) and yellow (positive) produced colors, we report for the first time the presence of an orange color cluster that may lead to wrong diagnosis. We also demonstrated using RT-qPCR and RT-LAMP that low viral loads are related to Ct values > 30, resulting in orange colors. We also demonstrated that the diagnosis of COVID-19 by colorimetric RT-LAMP is efficient until the fifth symptoms day when the viral load is still relatively high. Conclusion This study reports properties and indications for colorimetric RT-LAMP as point-of-care for SARS-CoV-2 diagnostic, reducing false results, interpretations and optimizing molecular diagnostics tests application.

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