scholarly journals Comparative evaluation of rapid isothermal amplification and antigen assays for screening testing of SARS-CoV-2

2021 ◽  
Author(s):  
Nol Salcedo ◽  
Brena F Sena ◽  
Xiying Qu ◽  
Bobby Brooke Herrera
Keyword(s):  
High Throughput Screening ◽  
Limit Of Detection ◽  
Low Cost ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Peak Period ◽  
Percent Agreement ◽  
Flow Test ◽  
Lateral Flow Test

Human transmission of SARS-CoV-2 and emergent variants of concern has continued to occur globally, despite mass vaccination campaigns. Public health strategies to reduce virus spread should therefore rely, in part, on frequent screening with rapid, inexpensive, and sensitive tests. We evaluated two digitally integrated rapid tests and assessed their performance using stored nasal swab specimens collected from individuals with or without COVID-19. An isothermal amplification assay combined with a lateral flow test had a limit of detection of 10 RNA copies per reaction, and a positive percent agreement (PPA)/negative percent agreement (NPA) during the asymptomatic and symptomatic phases of 100%/100% and 95.83/100%, respectively. Comparatively, an antigen-based lateral flow test, had a limit of detection of 30,000 copies, and a PPA/NPA during the asymptomatic and symptomatic phases of 82.86%/98.68% and 91.67/100%, respectively. Both the isothermal amplification and antigen-based lateral flow tests had optimized detection of SARS-CoV-2 during the peak period of transmission; however, the antigen-based test had reduced sensitivity in clinical samples with qPCR Ct values greater than 29.8. Low-cost, high-throughput screening enabled by isothermal amplification or antigen-based techniques have value for outbreak control.

A Loop-Mediated Isothermal Amplification (LAMP) Assay for the Detection of Treponema pallidum subsp. pertenue

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S128-S128
Author(s):  
Laud Anthony Basing
Keyword(s):  
Gold Standard ◽  
Limit Of Detection ◽  
Treponema Pallidum ◽  
Lamp Assay ◽  
Test Strip ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Flow Test ◽  
Lateral Flow Test

Abstract Objectives The eradication of yaws, a childhood disease caused by Treponema pallidum subsp. pertenue, is constrained by the lack of rapid, accurate diagnosis. We sought to develop a molecular point-of-care test for the diagnosis of yaws. Methods A loop-mediated isothermal amplification (LAMP) assay with primers targeting the conserved gene, tp0967, with visual detection by lateral flow test strip was developed. The assay was optimized by varying the concentrations of reagents as well as the temperature and time of the reaction. The limit of detection and selectivity of the assay were evaluated. Subsequently, 63 clinical samples from yaws-infected lesions were used to determine the sensitivity of the assay from both unextracted and DNA extracted swab samples as compared to the current molecular testing protocol (CDC PCR assay) as the gold standard. A further five clinical samples from lesions containing PCR-confirmed syphilis pathogen (Treponema pallidum subsp. pallidum) were tested to ensure specificity of the assay for yaws alone. Results The developed LAMP assay was found to be optimal when run at 65oC for 30 minutes. The limit of detection was 2.7*104 copies DNA per mL. Out of the 63 yaws samples tested, the CDC assay, extracted DNA LAMP assay, and unextracted DNA using the LAMP assay resulted in 12, 14, and 8 positive results, respectively. None of the syphilis samples tested positive in any of the assays. Conclusion We show the development of a fast and sensitive LAMP assay for Treponema pallidum subsp. pertenue detected by lateral flow test strip. Using extracted DNA, the assay sensitivity is on par with gold standard detection. Further, the assay can be adapted to minimal sample processing required for in-field detection without DNA extraction.

scholarly journals A low-cost smartphone-based platform for highly sensitive point-of-care testing with persistent luminescent phosphors

Lab on a Chip ◽  
2017 ◽  
Vol 17 (6) ◽  
pp. 1051-1059 ◽  
Author(s):  
Andrew S. Paterson ◽  
Balakrishnan Raja ◽  
Vinay Mandadi ◽  
Blane Townsend ◽  
Miles Lee ◽  
...  
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Test Strip ◽  
Lateral Flow ◽  
Point Of Care Testing ◽  
Flow Test ◽  
Highly Sensitive ◽  
Lateral Flow Test ◽  
Gated Imaging

Time-gated imaging on a smartphone of a lateral flow test strip run with persistent luminescent nanophosphors.

Development of a monoclonal antibody for the detection of xylazine in milk and its use in an immunochromatographic strip

2021 ◽  
Author(s):  
Mengjia Chao ◽  
Liqiang Liu ◽  
Aihong Wu ◽  
Shanshan Song ◽  
Xinxin Xu ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Gold Nanoparticle ◽  
Limit Of Detection ◽  
Lateral Flow ◽  
Immunochromatographic Strip ◽  
Naked Eye ◽  
Milk Samples ◽  
Flow Test ◽  
Lateral Flow Test

A gold nanoparticle-based lateral-flow test (GNT) strip was developed to detect xylazine (XYL) in milk. And the limit of detection (LOD) and cut-off value of the GNT assay were evaluated to be 20 and 200 ng mL−1 in milk samples by the naked eye.

scholarly journals Rapid and Visual Detection of SARS-CoV-2 Using Multiplex Reverse Transcription Loop-Mediated Isothermal Amplification Linked With Gold Nanoparticle-Based Lateral Flow Biosensor

2021 ◽  
Vol 11 ◽  
Author(s):  
Xu Chen ◽  
Qingxue Zhou ◽  
Shijun Li ◽  
Hao Yan ◽  
Bingcheng Chang ◽  
...  
Keyword(s):  
Reverse Transcription ◽  
Prevention And Control ◽  
Limit Of Detection ◽  
Rna Extraction ◽  
Lateral Flow ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Loop Mediated Isothermal Amplification ◽  
The World ◽  
And Control

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that has caused the outbreak of coronavirus disease 2019 (COVID-19) all over the world. In the absence of appropriate antiviral drugs or vaccines, developing a simple, rapid, and reliable assay for SARS-CoV-2 is necessary for the prevention and control of the COVID-19 transmission.MethodsA novel molecular diagnosis technique, named multiplex reverse transcription loop-mediated isothermal amplification, that has been linked to a nanoparticle-based lateral flow biosensor (mRT-LAMP-LFB) was applied to detect SARS-CoV-2 based on the SARS-CoV-2 RdRp and N genes, and the mRT-LAMP products were analyzed using nanoparticle-based lateral flow biosensor. The mRT-LAMP-LFB amplification conditions, including the target RNA concentration, amplification temperature, and time were optimized. The sensitivity and specificity of the mRT-LAMP-LFB method were tested in the current study, and the mRT-LAMP-LFB assay was applied to detect the SARS-CoV-2 virus from clinical samples and artificial sputum samples.ResultsThe SARS-CoV-2 specific primers based on the RdRp and N genes were valid for the establishment of mRT-LAMP-LFB assay to detect the SARS-CoV-2 virus. The multiple-RT-LAMP amplification condition was optimized at 63°C for 30 min. The full process, including reaction preparation, viral RNA extraction, RT-LAMP, and product identification, could be achieved in 80 min. The limit of detection (LoD) of the mRT-LAMP-LFB technology was 20 copies per reaction. The specificity of mRT-LAMP-LFB detection was 100%, and no cross-reactions to other respiratory pathogens were observed.ConclusionThe mRT-LAMP-LFB technique developed in the current study is a simple, rapid, and reliable method with great specificity and sensitivity when it comes to identifying SARS-CoV-2 virus for prevention and control of the COVID-19 disease, especially in resource-constrained regions of the world.

A rapid DNA lateral flow test for the detection of transgenic maize by isothermal amplification of the 35S promoter

2015 ◽  
Vol 7 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Claudia Kolm ◽  
Robert L. Mach ◽  
Rudolf Krska ◽  
Kurt Brunner
Keyword(s):  
Genetically Modified Organisms ◽  
Genetically Modified ◽  
Lateral Flow ◽  
Transgenic Maize ◽  
Isothermal Amplification ◽  
35S Promoter ◽  
Flow Test ◽  
Lateral Flow Test ◽  
Strip Test

A novel DNA strip test enables the detection of low amounts of the 35S promoter of genetically modified organisms.

scholarly journals Development of immunochromatographic lateral flow test for rapid detection of Clostridium perfringens α, β and ε toxins in clinical samples

2021 ◽  
Vol 24 (4) ◽  
pp. 497-507
Author(s):  
R Soliman ◽  
M. M. Magdy ◽  
A. Samir ◽  
Y. A. Abdalla ◽  
R. H. Sayed
Keyword(s):  
Guinea Pigs ◽  
Rapid Detection ◽  
Polyclonal Antibodies ◽  
Lateral Flow ◽  
Clinical Samples ◽  
Immunochromatographic Test ◽  
Flow Test ◽  
Faecal Samples ◽  
Lateral Flow Test ◽  
Sensitivity Specificity

In the present work a lateral flow immunochromatographic test (LFT) for rapid detection of Clostri­dium perfringens toxins types, alpha (α), beta (β) and epsilon (ε) in clinical samples was developed. C. perfringens toxins were prepared, purified and inactivated with 0.2% formalin. Polyclonal antibodies specific to C. perfringens toxins types α, β and ε toxoids were prepared in rabbits and guinea pigs. The toxoid specific polyclonal antibodies prepared in rabbits were labelled with gold chloride nanoparticles. The prepared toxin specific rabbit and guinea pigs antibodies and goat anti-rabbit antibodies were utilised in development of a lateral flow immunochromatographic test and the latter - evaluated for detection of C. perfringens α, β and ε toxins in clinical samples. The sensitivity and specificity and accuracy of the developed LFT were determined by comparison with a commercially available ELISA used for detection of these toxins. The prepared LFT was capable to detect C. perfringens α, β and ε toxins in quantities of 2 μg/ml, 250 ng/ml and 60 ng/ml, respectively. One hundred poultry suspected faecal samples was examined both with the prepared LFT and commercial ELISA to test the validity of developed LFT. The sensitivity, specificity and accuracy of the LFT for detection of C. perfringens toxins were 81%, 95.2% and 90%, respectively, for α toxin, 76.6%, 98.5% and 72%, respectively, for β toxin and 66.6%, 98.8% and 95%, respectively, for ε toxin.

Validation of a Rapid Lateral Flow Test for the Simultaneous Determination of β-Lactam Drugs and Flunixin in Raw Milk

2012 ◽  
Vol 75 (7) ◽  
pp. 1270-1277 ◽  
Author(s):  
DAVID DOUGLAS ◽  
KATIE BANASZEWSKI ◽  
RIMA JUSKELIS ◽  
FADWA AL-TAHER ◽  
YANG CHEN ◽  
...  
Keyword(s):  
Simultaneous Determination ◽  
Limit Of Detection ◽  
Agricultural Practices ◽  
Raw Milk ◽  
Lateral Flow ◽  
Penicillin G ◽  
Screening Programs ◽  
Flow Test ◽  
Lateral Flow Test

β-Lactam antibiotics are the most commonly used drugs on dairy farms. β-Lactam residues in milk are kept out of the human milk supply with good agricultural practices and mandatory truck screening performed by the dairy industry under Appendix N of the Pasteurized Milk Ordinance. Flunixin, a nonsteroidal and anti-inflammatory drug, appears in dairy cattle tissue residues with a frequency similar to the occurrence of penicillin G. This creates concern that flunixin residues could be in milk and would go undetected under current milk screening programs. A single test that combines mandatory β-lactam screening with voluntary flunixin screening is an economical approach for monitoring and controlling for potential flunixin or 5-hydroxyflunixin, the primary flunixin metabolite marker in milk. The objective of this study was to validate a β-lactam and flunixin rapid lateral flow test (LFT) and compare the results obtained with a liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of flunixin and 5-hydroxyflunixin in raw milk with a limit of detection of <1 ppb, equivalent to 1 ng/ml. Using the LFT, three combined manufactured lots of test strips detected penicillin G at 2.0 ppb, ampicillin at 6.8 ppb, amoxicillin at 5.9 ppb, cephapirin at 13.4 ppb, ceftiofur (total metabolites) at 63 ppb, and 5-hydroxyflunixin at 1.9 ppb at least 90% of the time with 95% confidence. The LFT also detected incurred flunixin milk samples that were analyzed with the LC-MS/MS and diluted to tolerance in raw milk. The detection levels for the LFT are lower than the U.S. safe levels or tolerances and qualify the test to be used in compliance with U.S. milk screening programs.

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.

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