scholarly journals Evaluation of the clinical performance of a magnetic force-assisted electrochemical immunoassay for the detection of SARS-CoV-2 antigens

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258394
Author(s):  
Sung Jin Jo ◽  
Sang-hyun Shin ◽  
Jungrok Kim ◽  
Seungok Lee ◽  
Jehoon Lee
Keyword(s):  
Magnetic Force ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Point Of Care ◽  
Electrical Current ◽  
Republic Of Korea ◽  
Nasopharyngeal Swab ◽  
Electrochemical Immunoassay ◽  
Rt Pcr ◽  
Viral Culture

Rapid antigen (Ag) tests for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) provide quick results, do not require specialized technical skills or infrastructure, and can be used as a point-of-care method to prevent the spread of coronavirus disease (COVID-19). The performance of a magnetic force-assisted electrochemical immunoassay-based test, namely the MARK-B COVID-19 Ag test (BBB, Sungnam, Republic of Korea), was evaluated using 170 nasopharyngeal swab specimens and compared to that of RT-PCR and commercial rapid Ag test (STANDARD Q COVID-19 Ag Test, SD Biosensor, Suwon-si, Republic of Korea). The overall sensitivity and specificity of the MARK-B test were 90.0% (95% CI 79.4%–96.2%) and 99.0% (95% CI 95.0%–99.9%), respectively, with a kappa coefficient of 0.908. The correlations between the electrical current values of MARK-B and the Ct values of RT-PCR were −0.898 (E gene, 95% CI −0.938 to −0.834) and −0.914 (RdRp gene, 95% CI −0.948 to −0.860), respectively. The limit of detection of the MARK-B was measured using the viral culture reference samples and found to be 1 x 102 pfu/mL. The magnetic force-assisted electrochemical immunoassay-based Ag test can be used to rapidly detect SARS-CoV-2 infections, and the corresponding fully automated portable device can provide easy readability and semi-quantitative results.

scholarly journals Diagnosis of SARS-Cov-2 Infection by RT-PCR Using Specimens Other Than Naso- and Oropharyngeal Swabs: A Systematic Review and Meta-Analysis

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 363
Author(s):  
Vânia M. Moreira ◽  
Paulo Mascarenhas ◽  
Vanessa Machado ◽  
João Botelho ◽  
José João Mendes ◽  
...  
Keyword(s):  
Systematic Review ◽  
Clinical Performance ◽  
Point Of Care ◽  
Meta Analysis ◽  
High Sensitivity ◽  
Nasopharyngeal Swab ◽  
Sample Collection ◽  
Rt Pcr ◽  
Oropharyngeal Swab ◽  
Nucleic Acid Assays

The rapid and accurate testing of SARS-CoV-2 infection is still crucial to mitigate, and eventually halt, the spread of this disease. Currently, nasopharyngeal swab (NPS) and oropharyngeal swab (OPS) are the recommended standard sampling techniques, yet, these have some limitations such as the complexity of collection. Hence, several other types of specimens that are easier to obtain are being tested as alternatives to nasal/throat swabs in nucleic acid assays for SARS-CoV-2 detection. This study aims to critically appraise and compare the clinical performance of RT-PCR tests using oral saliva, deep-throat saliva/posterior oropharyngeal saliva (DTS/POS), sputum, urine, feces, and tears/conjunctival swab (CS) against standard specimens (NPS, OPS, or a combination of both). In this systematic review and meta-analysis, five databases (PubMed, Scopus, Web of Science, ClinicalTrial.gov and NIPH Clinical Trial) were searched up to the 30th of December, 2020. Case-control and cohort studies on the detection of SARS-CoV-2 were included. The methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS 2). We identified 1560 entries, 33 of which (1.1%) met all required criteria and were included for the quantitative data analysis. Saliva presented the higher accuracy, 92.1% (95% CI: 70.0–98.3), with an estimated sensitivity of 83.9% (95% CI: 77.4–88.8) and specificity of 96.4% (95% CI: 89.5–98.8). DTS/POS samples had an overall accuracy of 79.7% (95% CI: 43.3–95.3), with an estimated sensitivity of 90.1% (95% CI: 83.3–96.9) and specificity of 63.1% (95% CI: 36.8–89.3). The remaining index specimens could not be adequately assessed given the lack of studies available. Our meta-analysis shows that saliva samples from the oral region provide a high sensitivity and specificity; therefore, these appear to be the best candidates for alternative specimens to NPS/OPS in SARS-CoV-2 detection, with suitable protocols for swab-free sample collection to be determined and validated in the future. The distinction between oral and extra-oral salivary samples will be crucial, since DTS/POS samples may induce a higher rate of false positives. Urine, feces, tears/CS and sputum seem unreliable for diagnosis. Saliva testing may increase testing capacity, ultimately promoting the implementation of truly deployable COVID-19 tests, which could either work at the point-of-care (e.g. hospitals, clinics) or at outbreak control spots (e.g., schools, airports, and nursing homes).

scholarly journals Clinical performance of the point-of-care cobas Liat for detection of SARS-CoV-2 in 20 minutes: A multicenter study

2020 ◽  
Author(s):  
Glen Hansen ◽  
Jamie Marino ◽  
Zi-Xuan Wang ◽  
Kathleen G. Beavis ◽  
John Rodrigo ◽  
...  
Keyword(s):  
Influenza A ◽  
Clinical Performance ◽  
Point Of Care ◽  
Nasopharyngeal Swab ◽  
Molecular Testing ◽  
Rt Pcr ◽  
Percent Agreement ◽  
Individual Care ◽  
Pcr Technology ◽  
Acid Test

Background: Highly accurate testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the point of care (POC) is an unmet diagnostic need in emergency care and time-sensitive outpatient care settings. Reverse transcription-polymerase chain reaction (RT-PCR) technology is the gold-standard for SARS-CoV-2 diagnostics. Methods: We performed a multi-site United States (US) study comparing the clinical performance of the first US Food and Drug Administration (FDA) authorized POC RT-PCR test for detection of SARS-CoV-2 in 20 minutes, the cobas® Liat SARS-CoV-2 & Influenza A/B nucleic acid test, to the most widely used RT-PCR laboratory test, the cobas® 68/8800 SARS-CoV-2 test. Results: Clinical nasopharyngeal swab specimens from 444 patients with 357 evaluable specimens at five US clinical laboratories were enrolled from September 21, 2020 to October 23, 2020. The overall agreement between the Liat and 68/8800 systems for SARS-CoV-2 diagnostics was 98.6% (352/357). Using Liat, positive percent agreement for SARS-CoV-2 was 100% (162/162) and the negative percent agreement was 97.4% (190/195). Conclusion: The Liat is an RT-PCR POC test that provides highly accurate SARS-CoV-2 results in 20 minutes with equivalent performance to high-throughput laboratory molecular testing. Rapid RT-PCR testing at the POC can enable more timely infection control and individual care decisions for Coronavirus Disease 2019.

scholarly journals Development and Evaluation of a new Swiss Made SARS-CoV-2 antigen-detecting rapid test

2021 ◽  
Author(s):  
Percevent J Ducrest
Keyword(s):  
Low Income ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Rapid Test ◽  
Negative Control ◽  
Low Income Countries ◽  
Nasopharyngeal Swab ◽  
Analytical Sensitivity ◽  
Rt Pcr ◽  
Gamma Irradiated

There is an urgent need in rapid diagnostic test (RDT) to detect antigen of SARS-CoV-2 to reduce the spread of COVID-19 outbreak. We have developed a rapid and simple point-of-care lateral flow immunoassay (LFIA) detecting nucleocapsid antigen of SARS-CoV-2 in 10 minutes. The aim of this study is to evaluate the diagnostic performance and analytical sensitivity of this RDT. RT-PCR positive nasopharyngeal swab samples (n=20) for SARS-CoV-2 and 40 negative control samples were studied. Analytical sensitivity was assessed using Gamma-irradiated SARS-CoV-2 and the limit of detection (LOD) was determined at 1.4 x 10^2 TCID50/ml. Overall, RDT diagnostic sensitivity was 90% (95% confidence interval [95%CI]: 67-98%) and specificity 98% (95% CI: 85-100%). The sensitivity was 100% (95% CI: 75-100%) when using only samples with a RT-PCR Cycle threshold lower than 30. This antigen RDT displays a high diagnostic accuracy for SARS‐CoV‐2 antigen detection in high COVID‐19 prevalence settings. Its use could be considered in the absence of routine RT-PCR facilities such in low-income countries.

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 Development and validation of direct RT-LAMP for SARS-CoV-2

2020 ◽  
Author(s):  
Abu Naser Mohon ◽  
Jana Hundt ◽  
Guido van Marle ◽  
Kanti Pabbaraju ◽  
Byron Berenger ◽  
...  
Keyword(s):  
Sindbis Virus ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Extraction Procedure ◽  
Lamp Assay ◽  
Cold Chain ◽  
Clinical Samples ◽  
Lamp Method ◽  
Rt Pcr ◽  
Percent Agreement

AbstractWe have developed a reverse-transcriptase loop mediated amplification (RT-LAMP) method targeting genes encoding the Spike (S) protein and RNA-dependent RNA polymerase (RdRP) of SARS-CoV-2. The LAMP assay achieves comparable limit of detection as commonly used RT-PCR protocols based on artificial targets, recombinant Sindbis virus, and clinical samples. Clinical validation of single-target (S gene) LAMP (N=120) showed a positive percent agreement (PPA) of 41/42 (97.62%) and negative percent agreement (NPA) of 77/78 (98.72%) compared to reference RT-PCR. Dual-target RT-LAMP (S and RdRP gene) achieved a PPA of 44/48 (91.97%) and NPA 72/72 (100%) when including discrepant samples. The assay can be performed without a formal extraction procedure, with lyophilized reagents which do need cold chain, and is amenable to point-of-care application with visual detection.

scholarly journals 369. Alternative Workflow for SARS-CoV-2 Testing Using a Heat Lysis Protocol for Respiratory Specimens

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S287-S287
Author(s):  
Meghna Yadav ◽  
Tiffany Martinez ◽  
Isabel Regoli ◽  
Osvaldo Hernandez ◽  
Phuong Le ◽  
...  
Keyword(s):  
Molecular Biology ◽  
Influenza A ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Extraction System ◽  
Nasopharyngeal Swab ◽  
Biomedical Sciences ◽  
Direct Extraction ◽  
Computational Molecular Biology ◽  
Extraction Protocol

Abstract Background The SARS-CoV-2 pandemic has demonstrated the need for streamlined workflows in high-throughput testing. In extraction-based testing, limited extraction reagents and required proprietary instrumentation may pose a bottleneck for labs. As a solution, ChromaCode developed a Direct Extraction protocol for the HDPCR™ SARS-CoV-2 Assay, distributed in accordance with the guidance on Policy for Coronavirus Disease-2019 Tests During the Public Health Emergency, Section IV.C., which allows for the processing of specimens without an extraction system. In lieu of an extraction system, the Direct Extraction protocol uses a thermal cycler to lyse and inactivate specimens which are directly added to the Polymerase Chain Reaction (PCR). Methods The Limit of Detection (LoD), Clinical Performance, and effect of Interfering Substances was determined for the Direct Extraction protocol. The LoD was established on 6 PCR platforms with dilutions of inactivated SARS-CoV-2 virus spiked into residual, negative nasopharyngeal swab (NPS) matrix. Clinical performance was assessed with 48 positive and 50 negative frozen retrospective samples using the Direct Extraction protocol compared to an external Emergency Use Authorized (EUA) comparator assays (cobas® Liat® SARS-CoV-2 & Influenza A/B assay and the Hologic Panther Fusion® SARS-CoV-2 Assay respectively) on three PCR platforms. The Direct Extraction protocol was evaluated for performance in the presence of 13 potentially interfering substances that can be present in a respiratory specimen. Results The LoD of the Direct Extraction protocol ranges from 1000 – 3000 genomic equivalents (GE)/mL. The clinical performance of the assay was 95.8% positive agreement (95% CI of 84.6% - 99.3%) and 100% negative agreement (95% CI of 90.9% - 100% or 91.1% – 100%) across all three PCR platforms tested. The viral target was detected at 3X LoD for all interferents tested. Conclusion The Direct Extraction protocol of ChromaCode’s SARS-CoV-2 Assay is a sensitive test that eliminates the need for sample extraction and performs very well against traditional extraction-based workflows. The inclusion of this protocol can reduce costs, reliance on extraction systems, and time associated with extraction-based protocols. Disclosures Meghna Yadav, Ph.D. Molecular Biology, ChromaCode Inc. (Employee, Shareholder) Tiffany Martinez, n/a, ChromaCode (Employee, Shareholder) Isabel Regoli, MS, Bioinformatics, ChromaCode (Employee, Shareholder) Osvaldo Hernandez, B.S., Molecular Biology, ChromaCode (Employee, Shareholder) Phuong Le, B.S., Biochemistry, ChromaCode (Employee, Shareholder) Heather Carolan, Masters, Computational Molecular Biology, ChromaCode (Employee, Shareholder) Brad Brown, Ph.D Biomedical Sciences, ChromaCode (Employee, Shareholder) Karen Menge, Ph.D. Biochemistry, ChromaCode (Employee, Shareholder)ChromaCode (Employee, Shareholder)

scholarly journals What was behind the first recognition and characterization of autochthonous SARS-CoV-2 transmission in Italy: who opened Pandora’s Box in Europe?

2021 ◽  
Author(s):  
Valeria Micheli ◽  
Alessandro Mancon ◽  
Annalisa Malara ◽  
Davide Mileto ◽  
Piergiorgio Villani ◽  
...  
Keyword(s):  
Emergency Room ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Respiratory Impairment ◽  
Viral Culture

An Italian male with no link to China SARS-CoV-2 epidemic presented at Emergency Room with severe respiratory impairment. The RT-PCR on 20th February, 2020, nasopharyngeal swab revealed SARS-CoV-2 infection, confirmed with viral culture and sequencing. This was the first identified autochthonous SARS-CoV-2 transmission in Italy, that unveiled global pathogen diffusion.

scholarly journals Rapid Isothermal Amplification and Portable Detection System for SARS-CoV-2

2020 ◽  
Author(s):  
A. Ganguli ◽  
A. Mostafa ◽  
J. Berger ◽  
M. Aydin ◽  
F. Sun ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Detection System ◽  
Point Of Care ◽  
Rna Extraction ◽  
Clinical Diagnostics ◽  
Isothermal Amplification ◽  
Sample Collection ◽  
Rt Pcr ◽  
Point Of Use ◽  
Viral Transport Medium

AbstractThe COVID-19 pandemic provides an urgent example where a gap exists between availability of state-of-the-art diagnostics and current needs. As assay details and primer sequences become widely known, many laboratories could perform diagnostic tests using methods such as RT-PCR or isothermal RT-LAMP amplification. A key advantage of RT-LAMP based approaches compared to RT-PCR is that RT-LAMP is known to be robust in detecting targets from unprocessed samples. In addition, RT-LAMP assays are performed at a constant temperature enabling speed, simplicity, and point-of-use testing. Here, we provide the details of an RT-LAMP isothermal assay for the detection of SARS-CoV-2 virus with performance comparable to currently approved tests using RT-PCR. We characterize the assay by introducing swabs in virus spiked synthetic nasal fluids, moving the swab to viral transport medium (VTM), and using a volume of that VTM for performing the amplification without an RNA extraction kit. The assay has a Limit-of-Detection (LOD) of 50 RNA copies/μL in the VTM solution within 20 minutes, and LOD of 5000 RNA copies/μL in the nasal solution. Additionally, we show the utility of this assay for real-time point-of-use testing by demonstrating detection of SARS-CoV-2 virus in less than 40 minutes using an additively manufactured cartridge and a smartphone-based reader. Finally, we explore the speed and cost advantages by comparing the required resources and workflows with RT-PCR. This work could accelerate the development and availability of SARS-CoV-2 diagnostics by proving alternatives to conventional laboratory benchtop tests.Significance StatementAn important limitation of the current assays for the detection of SARS-CoV-2 stem from their reliance on time- and labor-intensive and laboratory-based protocols for viral isolation, lysis, and removal of inhibiting materials. While RT-PCR remains the gold standard for performing clinical diagnostics to amplify the RNA sequences, there is an urgent need for alternative portable platforms that can provide rapid and accurate diagnosis, potentially at the point-of-use. Here, we present the details of an isothermal amplification-based detection of SARS-CoV-2, including the demonstration of a smartphone-based point-of-care device that can be used at the point of sample collection.

scholarly journals Clinical Performance of the Luminex NxTAG CoV Extended Panel for SARS-CoV-2 Detection in Nasopharyngeal Specimens from COVID-19 Patients in Hong Kong

2020 ◽  
Vol 58 (8) ◽  
Author(s):  
Jonathan Hon-Kwan Chen ◽  
Cyril Chik-Yan Yip ◽  
Jasper Fuk-Woo Chan ◽  
Rosana Wing-Shan Poon ◽  
Kelvin Kai-Wang To ◽  
...  
Keyword(s):  
Hong Kong ◽  
High Throughput ◽  
Clinical Performance ◽  
Diagnostic System ◽  
Molecular Diagnostic ◽  
N Gene ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Gene Target ◽  
E Gene

ABSTRACT In December 2019, the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was first reported in the Hubei province of China and later spread all over the world. There was an urgent need of a high-throughput molecular test for screening the COVID-19 patients in the community. The Luminex NxTAG CoV extended panel is a high-throughput FDA emergency use-authorized molecular diagnostic assay for SARS-CoV-2 detection. This system targets three genes (ORF1ab, N, and E genes) of SARS-CoV-2, the ORF1ab region of SARS-CoV, and the ORF5 region of MERS-CoV. In this study, we evaluated the diagnostic performance of this system with nasopharyngeal swab specimens of 214 suspected COVID-19 patients in Hong Kong. The results were compared with our routine COVID-19 reverse transcription-PCR (RT-PCR) protocol with a LightMix SarbecoV E-gene kit and an in-house RdRp/Hel RT-PCR assay. The NxTAG CoV extended panel demonstrated 97.8% sensitivity and 100% specificity to SARS-CoV-2 in nasopharyngeal specimens. On low-viral load specimens, the sensitivity of the NxTAG panel could still maintain at 85.71%. Strong agreement was observed between the NxTAG panel and the routine COVID-19 RT-PCR protocol (kappa value = 0.98). Overall, the E gene target of the NxTAG panel demonstrated the highest sensitivity among the three SARS-CoV-2 targets, while the N gene targets demonstrated the least. In conclusion, the NxTAG CoV extended panel is simple to use, and it has high diagnostic sensitivity and specificity to SARS-CoV-2 in nasopharyngeal specimens. We recommend this diagnostic system for high-throughput COVID-19 screening in the community.

scholarly journals Analytical validation of a highly sensitive point-of-care system for cardiac troponin I determination

2019 ◽  
Vol 58 (1) ◽  
pp. 138-145 ◽  
Author(s):  
Federica Braga ◽  
Elena Aloisio ◽  
Andrea Panzeri ◽  
Takahito Nakagawa ◽  
Mauro Panteghini
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Point Of Care ◽  
Total Error ◽  
Method Comparison ◽  
Reference Limit ◽  
Highly Sensitive ◽  
Limit Of Quantitation

Abstract Background Highly sensitive cardiac troponin assays (hs-cTn) are not available as point-of-care (POC) measurements. As rapid testing cannot be achieved at the expense of clinical performance, there is an urgent need to develop and rigorously validate POC hs-cTn. Konica Minolta (KM) has recently developed a surface plasmon-field enhanced fluorescence spectroscopy-based POC hs-cTn I system. Methods We validated the analytical characteristics of the KM POC system according to the international guidelines. Results Limit of blank (LoB) and limit of detection (LoD) were 0.35 and 0.62 ng/L, respectively, hs-cTn I concentrations corresponding to a total CV of 20%, 10% and 5% were 1.5, 3.9 and 11.0 ng/L, respectively. Method comparison studies showed that KM calibration was successfully traced to higher-order references. Limit of quantitation (LoQ), i.e. the hs-cTn I concentration having a total error of measurement of ≤34%, was 10.0 ng/L. The upper reference limit (URL) for 600 healthy blood donors was calculated at 12.2 ng/L (90% confidence interval [CI]: 9.2–39.2), while sex-partitioned URLs were 20.6 (males) and 10.7 ng/L (females), respectively (p < 0.0001). KM assay measured hs-cTn I concentrations >LoD in 65.7% of all reference individuals, in 76.7% of males and in 54.7% of females, respectively. Conclusions The KM system joins the characteristics of POC systems to the analytical performance of hs-cTn.

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