Automated liquid handling robot for rapid lateral flow assay development.

The lateral flow assay (LFA) is one of the most popular technologies on the point-of-care diagnostics market due to its low cost and ease of use, with applications ranging from pregnancy to environmental toxins to infectious disease. While the use of these tests is relatively straightforward, significant development time and effort are required to create tests that are both sensitive and specific. Workflows to guide the LFA development process exist but moving from target selection to an LFA that is ready for field testing can be labor intensive, resource heavy, and time consuming. To reduce the cost and the duration of the LFA development process, we introduce a novel development platform centered on the flexibility, speed, and throughput of an automated robotic liquid handling system. The system comprises LFA-specific hardware and software that enable large optimization experiments with discrete and continuous variables such as antibody pair selection or reagent concentration. Initial validation of the platform was demonstrated during development of a malaria LFA but was readily expanded to encompass development of SARS-CoV-2 and Mycobacterium tuberculosis LFAs. The validity of the platform, where optimization experiments are run directly on LFAs rather than in solution, was based on a direct comparison between the robotic system and a more traditional ELISA-like method. By minimizing hands-on time, maximizing experiment size, and enabling improved reproducibility, the robotic system improved the quality and quantity of LFA assay development efforts.

Time scale performance of rapid antigen testing for SARS-CoV-2: Evaluation of 10 rapid antigen assays.

There is a great demand for more rapid tests for SARS-CoV-2 detection to reduce waiting time, boost public health strategies for combating disease, decrease costs, and prevent overwhelming laboratory capacities. This study was conducted to assess the performance of 10 lateral flow device viral antigen immunoassays for the detection of SARS-CoV-2 in nasopharyngeal swab specimens. We analyzed 231 nasopharyngeal samples collected from October 2020 to December 2020, from suspected COVID-19 cases and contacts of positive cases at Biotechnology Research Center laboratories, Tripoli, Libya. The performance of 10 COVID-19 Antigen (Ag) rapid test devices for the detection of SARS-CoV-2 antigen was compared to a quantitative reverse transcription-polymerase chain reaction (RT-qPCR). In this study, 161 cases had symptoms consistent with COVID-19. The mean duration from symptom onset was 6.6 ± 4.3 days. The median cycle threshold (Ct ) of positive samples was 25. Among the 108 positive samples detected by RT-qPCR, the COVID-19 antigen (Ag) tests detected 83 cases correctly. All rapid Ag test devices used in this study showed 100% specificity. While tests from six manufacturers had an overall sensitivity range from 75% to 100%, the remaining four tests had a sensitivity of 50%-71.43%. Sensitivity during the first 6 days of symptoms and in samples with high viral loads (Ct < 25), was 100% in all but two of the test platforms. False-negative samples had a median Ct of 34 and an average duration of onset of symptoms of 11.3 days (range = 5-20 days). Antigen test diagnosis has high sensitivity and specificity in early disease when patients present less than 7 days of symptom onset. Patients are encouraged to test as soon as they get COVID-19-related symptoms within 1 week and to seek medical advice within 24 h if they develop disturbed smell/taste. The use of rapid antigen tests is important for controlling the COVID-19 pandemic and reducing the burden on molecular diagnostic laboratories.

Simple workflow to repurpose SARS-CoV-2 swab/serum samples for the isolation of cost-effective antibody/antigens for proteotyping applications and diagnosis.

Supply shortage for the development and production of preventive, therapeutic, and diagnosis tools during the COVID-19 pandemic is an important issue affecting the wealthy and poor nations alike. Antibodies and antigens are especially needed for the production of immunological-based testing tools such as point-of-care tests. Here, we propose a simple and quick magnetic nanoparticle (MNP)-based separation/isolation approach for the repurposing of infected human samples to produce specific antibodies and antigen cocktails. Initially, an antibody cocktail was purified from serums via precipitation and immunoaffinity chromatography. Purified antibodies were conjugated onto MNPs and used as an affinity matrix to separate antigens. The characterization process was performed by ELISA, SDS-PAGE, electrochemistry, isothermal titration calorimetry, and LC-Q-TOF-MS/MS analyses. The MNP-separated peptides can be used for mass spectrometry-based as well as paper-based lateral flow assay diagnostic. The exploitation of the current workflow for the development of efficient diagnostic tools, specific treatments, and fundamental research can significantly impact the present or eventual pandemic. This workflow can be considered as a two birds, one stone-like strategy.

One-pot high-yield synthesis of Pd nanocubes for Pd-Ir nanocube-based immunoassay of nucleocapsid protein from SARS-CoV-2.

Pd-Ir nanocubes are promising peroxidase-mimicking nanozymes for immunoassays, enabled by their excellent stability, relatively high catalytic activity, and reproducible performance. A key step involved in the preparation of Pd-Ir nanocubes is the synthesis of Pd nanocubes. However, the traditional method to synthesize Pd nanocubes requires sophisticated and expensive equipment to precisely control the reaction temperature and highly skilled technicians to achieve satisfactory and reproducible product yields. Herein, we report a simple, cost-effective, high-yield (> 99%) and one-pot strategy to synthesize Pd nanocubes with sizes of 7, 18, and 51 nm for the preparation of Pd-Ir nanocubes. The resulting 18 nm Pd-Ir nanocubes display three orders of magnitude higher peroxidase activity compared to horseradish peroxidase, leading to a significantly increased detection sensitivity when applied in the immunoassay of nucleocapsid protein from SARS-CoV-2. Due to the simplicity in both material synthesis and assaying procedures and the excellent detection sensitivity, our method should allow for the generalized application of Pd-Ir nanocube-based immunoassays for the diagnosis of human diseases.

A high-throughput microfluidic nanoimmunoassay for detecting anti-SARS-CoV-2 antibodies in serum or ultralow-volume blood samples.

Novel technologies are needed to facilitate large-scale detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific antibodies in human blood samples. Such technologies are essential to support seroprevalence studies and vaccine clinical trials, and to monitor quality and duration of immunity. We developed a microfluidic nanoimmunoassay (NIA) for the detection of anti-SARS-CoV-2 IgG antibodies in 1,024 samples per device. The method achieved a specificity of 100% and a sensitivity of 98% based on the analysis of 289 human serum samples. To eliminate the need for venipuncture, we developed low-cost, ultralow-volume whole blood sampling methods based on two commercial devices and repurposed a blood glucose test strip. The glucose test strip permits the collection, shipment, and analysis of 0.6 µL of whole blood easily obtainable from a simple finger prick. The NIA platform achieves high throughput, high sensitivity, and specificity based on the analysis of 289 human serum samples, and negligible reagent consumption. We furthermore demonstrate the possibility to combine NIA with decentralized and simple approaches to blood sample collection. We expect this technology to be applicable to current and future SARS-CoV-2 related serological studies and to protein biomarker analysis in general.

Performance of 30 commercial SARS-CoV-2 serology assays in testing symptomatic COVID-19 patients.

We report evaluation of 30 assays' (17 rapid tests (RDTs) and 13 automated/manual ELISA/CLIA assay (IAs)) clinical performances with 2594 sera collected from symptomatic patients with positive SARS-CoV-2 rRT-PCR on a respiratory sample, and 1996 pre-epidemic serum samples expected to be negative. Only 4 RDT and 3 IAs fitted both specificity (> 98%) and sensitivity (> 90%) criteria according to French recommendations. Serology may offer valuable information during COVID-19 pandemic, but inconsistent performances observed among the 30 commercial assays evaluated, which underlines the importance of independent evaluation before clinical implementation.

Point-of-care diagnostic tests for influenza in the emergency department: A cost-effectiveness analysis in a high-risk population from a Canadian perspective.

BACKGROUND: Our objective was to assess the cost-effectiveness of novel rapid diagnostic tests: rapid influenza diagnostic tests (RIDT), digital immunoassays (DIA), rapid nucleic acid amplification tests (NAAT), and other treatment algorithms for influenza in high-risk patients presenting to hospital with influenza-like illness (ILI). METHODS: We developed a decision-analytic model to assess the cost-effectiveness of diagnostic test strategies (RIDT, DIA, NAAT, clinical judgement, batch polymerase chain reaction) preceding treatment; no diagnostic testing and treating everyone; and not treating anyone. We modeled high-risk 65-year old patients from a health payer perspective and accrued outcomes over a patient's lifetime. We reported health outcomes, quality-adjusted life years (QALYs), healthcare costs, and net health benefit (NHB) to measure cost-effectiveness per cohort of 100,000 patients. RESULTS: Treating everyone with no prior testing was the most cost-effective strategy, at a cost-effectiveness threshold of $50,000/QALY, in over 85% of simulations. This strategy yielded the highest NHB of 15.0344 QALYs, but inappropriately treats all patients without influenza. Of the novel rapid diagnostics, NAAT resulted in the highest NHB (15.0277 QALYs), and the least number of deaths (1,571 per 100,000). Sensitivity analyses determined that results were most impacted by the pretest probability of ILI being influenza, diagnostic test sensitivity, and treatment effectiveness. CONCLUSIONS: Based on our model, treating high-risk patients presenting to hospital with influenza-like illness, without performing a novel rapid diagnostic test, resulted in the highest NHB and was most cost-effective. However, consideration of whether treatment is appropriate in the absence of diagnostic confirmation should be taken into account for decision-making by clinicians and policymakers.

A novel rapid detection for SARS-CoV-2 spike 1 antigens using human angiotensin converting enzyme 2 (ACE2).

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), a newly emerging human infectious disease. Because no specific antiviral drugs or vaccines are available to treat COVID-19, early diagnostics, isolation, and prevention are crucial for containing the outbreak. Molecular diagnostics using reverse transcription polymerase chain reaction (RT-PCR) are the current gold standard for detection. However, viral RNAs are much less stable during transport and storage than proteins such as antigens and antibodies. Consequently, false-negative RT-PCR results can occur due to inadequate collection of clinical specimens or poor handling of a specimen during testing. Although antigen immunoassays are stable diagnostics for detection of past infection, infection progress, and transmission dynamics, no matched antibody pair for immunoassay of SARS-CoV-2 antigens has yet been reported. In this study, we designed and developed a novel rapid detection method for SARS-CoV-2 spike 1 (S1) protein using the SARS-CoV-2 receptor ACE2, which can form matched pairs with commercially available antibodies. ACE2 and S1-mAb were paired with each other for capture and detection in a lateral flow immunoassay (LFIA) that did not cross-react with SARS-CoV Spike 1 or MERS-CoV Spike 1 protein. The SARS-CoV-2 S1 (<5 ng of recombinant proteins/reaction) was detected by the ACE2-based LFIA. The limit of detection of our ACE2-LFIA was 1.86 × 105 copies/mL in the clinical specimen of COVID-19 Patients without no cross-reactivity for nasal swabs from healthy subjects. This is the first study to detect SARS-CoV-2 S1 antigen using an LFIA with matched pair consisting of ACE2 and antibody. Our findings will be helpful to detect the S1 antigen of SARS-CoV-2 from COVID-19 patients.

Diagnostic performance of commercially available COVID-19 serology tests in Brazil.

Timely and accurate laboratory testing is essential for managing the global COVID-19 pandemic. Reverse transcription polymerase chain reaction remains the gold-standard for SARS-CoV-2 diagnosis, but several practical issues limit the test's use. Immunoassays have been indicated as an alternative for individual and mass testing. OBJECTIVES: To access the performance of 12 serological tests for COVID-19 diagnosis. METHODS: We conducted a blind evaluation of six lateral-flow immunoassays (LFIAs) and six enzyme-linked immunosorbent assays (ELISAs) commercially available in Brazil for detecting anti-SARS-CoV-2 antibodies. RESULTS: Considering patients with seven or more days of symptoms, the sensitivity ranged from 59.5% to 83.1% for LFIAs and from 50.7% to 92.6% for ELISAs. For both methods, the sensitivity increased with clinical severity and days of symptoms. The agreement among LFIAs performed with digital blood and serum was moderate. Specificity was, in general, higher for LFIAs than for ELISAs. Infectious diseases prevalent in the tropics, such as HIV, leishmaniasis, arboviruses, and malaria, represent conditions with the potential to cause false-positive results with these tests, which significantly compromises their specificity. CONCLUSION: The performance of immunoassays was only moderate, affected by the duration and clinical severity of the disease. Absence of discriminatory power between IgM/IgA and IgG has also been demonstrated, which prevents the use of acute-phase antibodies for decisions on social isolation.