scholarly journals Brief Communication: Magnetic Immuno-Detection of SARS-CoV-2 specific Antibodies

2020 ◽  
Author(s):  
Jan Pietschmann ◽  
Nadja Vöpel ◽  
Holger Spiegel ◽  
Hans-Joachim Krause ◽  
Florian Schröper
Keyword(s):  
Magnetic Nanoparticles ◽  
Human Serum ◽  
Point Of Care ◽  
Lateral Flow ◽  
Antibody Detection ◽  
Diagnostic Systems ◽  
Antibody Testing ◽  
Detection Range ◽  
Specific Antibodies ◽  
Detection Technology

AbstractSARS-CoV-2 causes ongoing infections worldwide, and identifying people with immunity is becoming increasingly important. Available point-of-care diagnostic systems as lateral flow assays have high potential for fast and easy on-site antibody testing but are lacking specificity, sensitivity or possibility for quantitative measurements. Here, a new point-of-care approach for SARS-CoV-2 specific antibody detection in human serum based on magnetic immuno-detection is described and compared to standard ELISA. For magnetic immuno-detection, immunofiltration columns were coated with a SARS-CoV-2 spike protein peptide. SARS-CoV-2 peptide reactive antibodies, spiked at different concentrations into PBS and human serum, were rinsed through immunofiltration columns. Specific antibodies were retained within the IFC and labelled with an isotype specific biotinylated antibody. Streptavidin-functionalized magnetic nanoparticles were applied to label the secondary antibodies. Enriched magnetic nanoparticles were then detected by means of frequency magnetic mixing detection technology, using a portable magnetic read-out device. Measuring signals corresponded to the amount of SARS-CoV-2 specific antibodies in the sample. Our preliminary magnetic immuno-detection setup resulted in a higher sensitivity and broader detection range and was four times faster than ELISA. Further optimizations could reduce assay times to that of a typical lateral flow assay, enabling a fast and easy approach, well suited for point-of-care measurements without expensive lab equipment.

scholarly journals A Paper-based Immunofluorescent Device for the Detection of SARS-CoV-2 Humanized Antibody

2021 ◽  
Author(s):  
Surasak Kasetsirikul ◽  
Muhammad Umer ◽  
Narshone Soda ◽  
Kamalalayam Rajan Sreejith ◽  
Muhammad J. A. Shiddiky ◽  
...  
Keyword(s):  
Human Serum ◽  
Point Of Care ◽  
Serum Samples ◽  
Igg Antibody ◽  
Healthy Human ◽  
Specific Antibodies ◽  
Human Serum Samples ◽  
Humanized Antibody ◽  
Relative Standard ◽  
Humanized Antibodies

We report on an immunofluorescent paper-based assay for the detection of severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) humanized antibody. The paper-based device was fabricated by using lamination technique for easy and optimized handling. Our approach utilises a two-step strategy that involves (i) initial coating of the paper-electrode with recombinant SARS-CoV-2 nucleocapsid antigen to capture the target SARS-CoV-2 specific antibodies, and (ii) subsequent detection of SARS-CoV-2 antibodies using fluorophore-conjugated IgG antibody. The fluorescence readout was observed with fluorescence microscopy. The images were processed and quantified using a MATLAB program. The assay can selectively detect SARS-CoV-2 humanized antibodies spiked in PBS and healthy human serum samples with the relative standard deviation of approximately 6.4% (for n = 3). It has broad dynamic ranges (1 ng to 50 ng/µL in PBS and 5 to 100 ng/µL in human serum samples) for SARS-CoV-2 humanized antibodies with the detection limits of 2 ng/µL (0.025 IU/mL) and 10 ng/µL (0.125 IU/mL) in PBS and human serum samples, respectively. We believe that our assay has the potential to be used as a simple, rapid, and inexpensive paper-based diagnostic device with a portable fluorescent reader to provide point-of-care diagnosis. This assay can be used for rapid examination of a large batch of samples toward clinical screening of SARS-CoV-2 specific antibodies as a confirmed infected active case or to evaluate the immune response to a SARS-CoV-2 vaccine.

scholarly journals Engineering luminescent biosensors for point-of-care SARS-CoV-2 antibody detection

2020 ◽  
Author(s):  
Susanna K. Elledge ◽  
Xin X. Zhou ◽  
James R. Byrnes ◽  
Alexander J. Martinko ◽  
Irene Lui ◽  
...  
Keyword(s):  
Whole Blood ◽  
Point Of Care ◽  
Low Cost ◽  
Lateral Flow ◽  
Antibody Detection ◽  
Lateral Flow Assays ◽  
Quantitative Results ◽  
Development And Validation ◽  
Antibody Tests ◽  
Split Luciferase

Current serology tests for SARS-CoV-2 antibodies mainly take the form of enzyme-linked immunosorbent assays or lateral flow assays, with the former being laborious and the latter being expensive and often lacking sufficient sensitivity and scalability. Here we present the development and validation of a rapid, low-cost solution-based assay to detect antibodies in serum, plasma, whole blood, and saliva, using rationally designed split luciferase antibody biosensors (spLUC). This new assay, which generates quantitative results in as short as 5 minutes, substantially reduces the complexity and improves the scalability of COVID-19 antibody tests for point-of-care and broad population testing.

scholarly journals Acceptability, usability and performance of lateral flow immunoassay tests for SARS-CoV-2 antibodies: REACT-2 study of self-testing in non-healthcare key workers

2021 ◽  
Author(s):  
Bethan Davies ◽  
Marzieh Araghi ◽  
Maya Moshe ◽  
He Gao ◽  
Kimberly Bennet ◽  
...  
Keyword(s):  
Point Of Care ◽  
Venous Blood ◽  
Fire Service ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Antibody Testing ◽  
Prevalence Studies ◽  
Similar Performance ◽  
Self Test ◽  
The Uk

Abstract Background Seroprevalence studies are essential to understand the epidemiology of SARS-CoV-2. Various technologies, including laboratory assays and point-of-care self-tests, are available for antibody testing. The interpretation of seroprevalence studies requires comparative data on the performance of antibody tests. Methods In June 2020, current and former members of the UK Police forces and Fire service performed a self-test lateral flow immunoassay (LFIA), had a nurse-performed LFIA and provided a venous blood sample for ELISA . We present the prevalence of antibodies to SARS-CoV-2; the acceptability and usability of self-test LFIAs; and determine the sensitivity and specificity of LFIAs compared to laboratory ELISA. Results In this cohort of 5189 current and former members of the Police service and 263 members of the Fire service, 7.4% (396/5,348; 95% CI, 6.7-8.1) were antibody positive. Seroprevalence was 8.9% (6.9-11.4) in those under 40 years, 11.5% (8.8-15.0) in those of non-white ethnicity and 7.8% (7.1-8.7) in those currently working. Self-test LFIA had an acceptability of 97.7% and a usability of 90.0%. There was substantial agreement between within-participant LFIA results (kappa 0.80; 0.77-0.83). The LFIAs had a similar performance: compared to ELISA, sensitivity was 82.1% (77.7-86.0) self-test and 76.4% (71.9-80.5) nurse-performed with specificity of 97.8% (97.3-98.2) and 98.5% (98.1-98.8) respectively. Conclusion A greater proportion of this non-healthcare key worker cohort showed evidence of previous infection with SARS-CoV-2 than the general population at 6.0% (5.8-6.1) following the first wave in England. The high acceptability and usability reported by participants and similar performance of self-test and nurse-performed LFIAs indicate that the self-test LFIA is fit for purpose for home-testing in occupational and community prevalence studies.

scholarly journals Evaluation of Serological SARS-CoV-2 Lateral Flow Assays for Rapid Point of Care Testing

2020 ◽  
Author(s):  
Steven E Conklin ◽  
Kathryn Martin ◽  
Yukari C Manabe ◽  
Haley A Schmidt ◽  
Morgan Keruly ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Symptom Onset ◽  
Point Of Care ◽  
Negative Control ◽  
Lateral Flow ◽  
Point Of Care Testing ◽  
Specific Antibodies ◽  
Testing Performance ◽  
Lateral Flow Assays ◽  
Point Of Care Tests

Background. Rapid point-of-care tests (POCTs) for SARS-CoV-2-specific antibodies vary in performance. A critical need exists to perform head-to-head comparison of these assays. Methods. Performance of fifteen different lateral flow POCTs for the detection of SARS-CoV-2-specific antibodies was performed on a well characterized set of 100 samples. Of these, 40 samples from known SARS-CoV-2-infected, convalescent individuals (average of 45 days post symptom onset) were used to assess sensitivity. Sixty samples from the pre-pandemic era (negative control), that were known to have been infected with other respiratory viruses (rhinoviruses A, B, C and/or coronavirus 229E, HKU1, NL63 OC43) were used to assess specificity. The timing of seroconversion was assessed on five POCTs on a panel of 272 longitudinal samples from 47 patients of known time since symptom onset. Results. For the assays that were evaluated, the sensitivity and specificity for any reactive band ranged from 55%-97% and 78%-100%, respectively. When assessing the performance of the IgM and the IgG bands alone, sensitivity and specificity ranged from 0%-88% and 80%-100% for IgM and 25%-95% and 90%-100% for IgG. Longitudinal testing revealed that median time post symptom onset to a positive result was 7 days (IQR 5.4, 9.8) for IgM and 8.2 days (IQR 6.3 to 11.3). Conclusion. The testing performance varied widely among POCTs with most variation related to the sensitivity of the assays. The IgM band was most likely to misclassify pre-pandemic samples. The appearance of IgM and IgG bands occurred almost simultaneously.

scholarly journals Evaluation of Serological SARS-CoV-2 Lateral Flow Assays for Rapid Point of Care Testing

2020 ◽  
Author(s):  
Steven E. Conklin ◽  
Kathryn Martin ◽  
Yukari C Manabe ◽  
Haley A Schmidt ◽  
Jernelle Miller ◽  
...  
Keyword(s):  
Sensitivity And Specificity ◽  
Symptom Onset ◽  
Point Of Care ◽  
Negative Control ◽  
Lateral Flow ◽  
Point Of Care Testing ◽  
Specific Antibodies ◽  
Testing Performance ◽  
Lateral Flow Assays ◽  
Point Of Care Tests

Background. Rapid point-of-care tests (POCTs) for SARS-CoV-2-specific antibodies vary in performance. A critical need exists to perform head-to-head comparison of these assays. Methods. Performance of fifteen different lateral flow POCTs for the detection of SARS-CoV-2-specific antibodies was performed on a well characterized set of 100 samples. Of these, 40 samples from known SARS-CoV-2-infected, convalescent individuals (average of 45 days post symptom onset) were used to assess sensitivity. Sixty samples from the pre-pandemic era (negative control), that were known to have been infected with other respiratory viruses (rhinoviruses A, B, C and/or coronavirus 229E, HKU1, NL63 OC43) were used to assess specificity. The timing of seroconversion was assessed on five LFAs on a panel of 272 longitudinal samples from 47 patients of known time since symptom onset. Results. For the assays that were evaluated, the sensitivity and specificity for any reactive band ranged from 55%-97% and 78%-100%, respectively. When assessing the performance of the IgM and the IgG bands alone, sensitivity and specificity ranged from 0%-88% and 80%-100% for IgM and 25%-95% and 90%-100% for IgG. Longitudinal testing revealed that median time post symptom onset to a positive result was 7 days (IQR 5.4, 9.8) for IgM and 8.2 days (IQR 6.3 to 11.3) for IgG. Conclusion. The testing performance varied widely among LFAs with most variation related to the sensitivity of the assays. The IgM band was most likely to misclassify pre-pandemic samples. The appearance of IgM and IgG bands occurred almost simultaneously.

scholarly journals User experience analysis of AbC-19 Rapid Test via lateral flow immunoassays for self-administrated SARS-CoV-2 antibody testing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Min Jing ◽  
Raymond Bond ◽  
Louise J. Robertson ◽  
Julie Moore ◽  
Amanda Kowalczyk ◽  
...  
Keyword(s):  
User Experience ◽  
General Public ◽  
Latent Dirichlet Allocation ◽  
Point Of Care ◽  
Rapid Test ◽  
Lateral Flow ◽  
Free Text ◽  
Antibody Testing ◽  
Kappa Score ◽  
Allocation Model

AbstractLateral flow immunoassays are low cost, rapid and highly efficacious point-of-care devices, which have been used for SARS-CoV-2 antibody testing by professionals. However, there is a lack of understanding about how self-administered tests are used by the general public for mass testing in different environmental settings. The purpose of this study was to assess the user experience (UX) (including usability) of a self-testing kit to identify COVID-19 antibodies used by a representative sample of the public in their cars, which included 1544 participants in Northern Ireland. The results based on 5-point Likert ratings from a post-test questionnaire achieved an average UX score of 96.03% [95% confidence interval (CI) 95.05–97.01%], suggesting a good degree of user experience. The results of the Wilcoxon rank sum tests suggest that UX scores were independent of the user’s age and education level although the confidence in this conclusion could be strengthened by including more participants aged younger than 18 and those with only primary or secondary education. The agreement between the test result as interpreted by the participant and the researcher was 95.85% [95% CI 94.85–96.85%], Kappa score 0.75 [95% CI 0.69–0.81] (indicating substantial agreement). Text analysis via the latent Dirichlet allocation model for the free text responses in the survey suggest that the user experience could be improved for blood-sample collection, by modifying the method of sample transfer to the test device and giving clearer instructions on how to interpret the test results. The overall findings provide an insight into the opportunities for improving the design of SARS-CoV-2 antibody testing kits to be used by the general public and therefore inform protocols for future user experience studies of point-of-care tests.

scholarly journals Clinical Utility of a Highly Sensitive Lateral Flow Immunoassay as determined by Titer Analysis for the Detection of anti-SARS-CoV-2 Antibodies at the Point-of-Care

2020 ◽  
Author(s):  
Amanda Haymond ◽  
Claudius Mueller ◽  
Hannah Steinberg ◽  
K. Alex Hodge ◽  
Caitlin W Lehman ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Best Practice ◽  
Point Of Care ◽  
Neutralization Assay ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antibody Testing ◽  
Roc Curve Analysis ◽  
Viral Neutralization

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), became a pandemic in early 2020. Lateral flow immunoassays for antibody testing have been viewed as a cheap and rapidly deployable method for determining previous infection with SARS-CoV-2; however, these assays have shown unacceptably low sensitivity. We report on nine lateral flow immunoassays currently available and compare their titer sensitivity in serum to a best-practice enzyme-linked immunosorbent assay (ELISA) and viral neutralization assay. For a small group of PCR-positive, we found two lateral flow immunoassay devices with titer sensitivity roughly equal to the ELISA; these devices were positive for all PCR-positive patients harboring SARS-CoV-2 neutralizing antibodies. One of these devices was deployed in Northern Italy to test its sensitivity and specificity in a real-world clinical setting. Using the device with fingerstick blood on a cohort of 27 hospitalized PCR-positive patients and seven hospitalized controls, ROC curve analysis gave AUC values of 0.7646 for IgG. For comparison, this assay was also tested with saliva from the same patient population and showed reduced discrimination between cases and controls with AUC values of 0.6841 for IgG. Furthermore, during viral neutralization testing, one patient was discovered to harbor autoantibodies to ACE2, with implications for how immune responses are profiled. We show here through a proof-of-concept study that these lateral flow devices can be as analytically sensitive as ELISAs and adopted into hospital protocols; however, additional improvements to these devices remain necessary before their clinical deployment.

scholarly journals Comparative assessment of multiple COVID-19 serological technologies supports continued evaluation of point-of-care lateral flow assays in hospital and community healthcare settings

2020 ◽  
Author(s):  
Suzanne Pickering ◽  
Gilberto Betancor ◽  
Rui Pedro Galão ◽  
Blair Merrick ◽  
Adrian W. Signell ◽  
...  
Keyword(s):  
Point Of Care ◽  
Antibody Test ◽  
Lateral Flow ◽  
Diagnostic Tools ◽  
Antibody Testing ◽  
Community Healthcare ◽  
Diagnostic Assays ◽  
Healthcare Settings ◽  
Lateral Flow Assays ◽  
Diagnostic Capabilities

AbstractThere is a clear requirement for an accurate SARS-CoV-2 antibody test, both as a complement to existing diagnostic capabilities and for determining community seroprevalence. We therefore evaluated the performance of a variety of antibody testing technologies and their potential as diagnostic tools. A highly specific in-house ELISA was developed for the detection of anti-spike (S), -receptor binding domain (RBD) and -nucleocapsid (N) antibodies and used for the cross-comparison of ten commercial serological assays – a chemiluminescence-based platform, two ELISAs and seven colloidal gold lateral flow immunoassays (LFIAs) – on an identical panel of 110 SARS-CoV-2-positive samples and 50 pre-pandemic negatives. There was a wide variation in the performance of the different platforms, with specificity ranging from 82% to 100%, and overall sensitivity from 60.9% to 87.3%. However, the head-to-head comparison of multiple sero-diagnostic assays on identical sample sets revealed that performance is highly dependent on the time of sampling, with sensitivities of over 95% seen in several tests when assessing samples from more than 20 days post onset of symptoms. Furthermore, these analyses identified clear outlying samples that were negative in all tests, but were later shown to be from individuals with mildest disease presentation. Rigorous comparison of antibody testing platforms will inform the deployment of point-of-care technologies in healthcare settings and their use in the monitoring of SARS-CoV-2 infections.

A Miniaturized Giant Magnetic Resistance System for Quantitative Detection of Methamphetamine

The Analyst ◽  
2021 ◽  
Author(s):  
Jinhong Guo ◽  
Guopan Yang ◽  
Kunxue Cheng ◽  
Zhengkang Chu ◽  
Yusheng Fu ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Point Of Care ◽  
Lateral Flow ◽  
Quantitative Detection ◽  
Point Of Care Testing ◽  
Resistance System ◽  
Magnetic Resistance

Point-of-care testing (POCT) systems have been greatly developed in recent years. Among them, lateral flow immunochromatography (LFIA) based on magnetic nanoparticles (MNPs) is widely used in various fields due to...

scholarly journals A new combination testing methodology to identify accurate and economical point-of-care testing strategies

2021 ◽  
Author(s):  
Sanjay Jain ◽  
Jonas Oddur Jonasson ◽  
Jean Pauphilet ◽  
Barnaby Flower ◽  
Maya Moshe ◽  
...  
Keyword(s):  
Point Of Care ◽  
Lateral Flow ◽  
Detection Methods ◽  
Antibody Detection ◽  
Single Test ◽  
Point Of Care Testing ◽  
Serum Samples ◽  
The Us ◽  
Index Tests ◽  
The Uk

Background: Quick, cheap and accurate point-of-care testing is urgently needed to enable frequent, large-scale testing to contain COVID-19. Lateral flow tests for antigen and antibody detection are an obvious candidate for use in community-wide testing, because they are quick and cheap relative to lab-processed tests. However, their low accuracy has limited their adoption. We develop a new methodology to increase the diagnostic accuracy of a combination of cheap, quick and inaccurate index tests with correlated or discordant outcomes, and illustrate its performance on commercially available lateral flow immunoassays (LFIAs) for Sars-CoV-2 antibody detection. Methods and Findings: We analyze laboratory test outcomes of 300 serum samples from health care workers detected with PCR-confirmed SARS-Cov-2 infection at least 21 days prior to sample collection, and 500 pre-pandemic serum samples, from a national seroprevalence survey, tested using eight LFIAs (Abbott, Biosure/Mologic, Orientgene-Menarini, Fortress, Biopanda I, Biopanda II, SureScreen and Wondfo) and Hybrid DABA as reference test. For each of 14 two-test combinations (e.g., Abbott, Fortress) and 16 three-test combinations (e.g., Abbott, Fortress, Biosure/Mologic) used on at least 100 positive and 100 negative samples, we classify an outcome sequence -- e.g., (+,-) for (Abbott, Fortress) -- as positive if its combination positive predictive value (CPPV) exceeds a given threshold, set between 0 and 1. Our main outcome measures are the sensitivity and specificity of different classification rules for classifying the outcomes of a combination test. We define testing possibility frontiers which represent sensitivity and false positive rates for different thresholds. The envelope of frontiers further enables test selection. The eight index tests individually meet neither the UK Medicines and Healthcare Products Regulatory Agency's 98% sensitivity and 98% specificity criterion, nor the US Center for Disease Control's 99.5% specificity criterion. Among these eight tests, the highest single-test LFIA specificity is 99.4% (with a sensitivity of 65.2%) and the highest single-test LFIA sensitivity is 93.4% (with a specificity of 97.4%). Using our methodology, a two-test combination meets the UK Medicines and Healthcare Products Regulatory Agency's criterion, achieving sensitivity of 98.4% and specificity of 98.0%. While two-test combinations meeting the US Center for Disease Control's 99.5% specificity criterion have sensitivity below 83.6%, a three-test combination delivers a specificity of 99.6% and a sensitivity of 95.8%. Conclusions: Current CDC guidelines suggest combining tests, noting that 'performance of orthogonal testing algorithms has not been systematically evaluated' and highlighting discordant outcomes. Our methodology combines available LFIAs to meet desired accuracy criteria, by identifying testing possibility frontiers which encompass benchmarks, enabling cost savings. Our methodology applies equally to antigen testing and can greatly expand testing capacity through combining less accurate tests, especially for use cases needing quick, accurate tests, e.g., entry to public spaces such as airports, nursing homes or hospitals.

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