Figure 5 - available via license: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Content may be subject to copyright.
Rapid antigen and rapid antibody tests. (A) Analytical workflow of rapid antigen test for the rapid detection of SARS-CoV-2 viral antigens through lateral flow immunoassay. (B) Analytical workflow of rapid antibody test for the rapid detection of human IgA, IgG or IgM antibodies against SARS-CoV-2 antigens through lateral flow immunoassay.
Source publication
The Coronavirus Disease 2019 (COVID‑19) pandemic has forced the scientific community to rapidly develop highly reliable diagnostic methods in order to effectively and accurately diagnose this pathology, thus limiting the spread of infection. Although the structural and molecular characteristics of the severe acute respiratory syndrome coronavirus 2...
Contexts in source publication
Context 1
... the sample. Finally, the buffer flows further to the control line where anti-antibodies specific for the conjugated control rabbit antibodies are immobilized; if the test is performed correctly, the reaction between these two molecules also gives rise to a colorimetric reaction. To be trusted, the test control line must always be positive (73,74) (Fig. ...
Context 2
... antigen complex binds to the human anti-antibodies immobilized in the test line determining a colorimetric reaction which indicates the positivity of the sample. Finally, the gold-tagged control rabbit antibodies flow to the control line binding anti-rabbit antibodies thus giving rise to a confirmatory colorimetric reaction (75,76) (Fig. ...
Citations
... Clinical statistics show that anti-CHIKV lgM is only detectable from day 4 to day 7 of sickness, resulting in false-negative results [6]. Due to their higher sensitivity and specificity, molecular diagnostic techniques can detect viruses early in infection within the window period of pathogen-specific antibody/antigen detection [7]. Recently, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) has been widely used in detecting various viruses, including CHIKV [8]. ...
Chikungunya virus, a mosquito-borne virus that causes epidemics, is often misdiagnosed due to symptom similarities with other arboviruses. Here, a portable and integrated nucleic acid-based diagnostic device, which combines reverse transcription-loop-mediated isothermal amplification and lateral-flow detection, was developed. The device is simple to use, precise, equipment-free, and highly sensitive, enabling rapid chikungunya virus identification. The result can be obtained by the naked eye within 40 min. The assay can effectively distinguish chikungunya virus from dengue virus, Japanese encephalitis virus, Zika virus, and yellow fever virus with high specificity and sensitivity as low as 598.46 copies mL−1. It has many benefits for the community screening and monitoring of chikungunya virus in resource-limited areas because of its effectiveness and simplicity. The platform has great potential for the rapid nucleic acid detection of other viruses.
... For example, the Coronavirus Disease 2019 (COVID-19) pandemic has caused global changes in the delivery of healthcare services since 2019, including both outpatient community-based services and inpatient hospital-admission services [34]. During the COVID-19 pandemic, an accurate non-invasive CRC screening test could be an alternative to colonoscopy to reduce the risk of the transmission of infectious diseases and to relieve the workload in healthcare sectors [35,36]. ...
Colorectal cancer (CRC) is one of the most prevalent cancers and the second leading cause of cancer deaths in developed countries. Early CRC may have no symptoms and symptoms usually appear with more advanced diseases. Regular screening can identify people who are at increased risk of CRC in order to offer earlier treatment. A cost-effective non-invasive platform for the screening and monitoring of CRC patients allows early detection and appropriate treatment of the disease, and the timely application of adjuvant therapy after surgical operation is needed. In this study, a cohort of 71 plasma samples that include 48 colonoscopy- and histopathology-confirmed CRC patients with TNM stages I to IV were recruited between 2017 and 2019. Plasma mRNA profiling was performed in CRC patients using NanoString nCounter. Normalized data were analyzed using a Mann–Whitney U test to determine statistically significant differences between samples from CRC patients and healthy subjects. A multiple-group comparison of clinical phenotypes was performed using the Kruskal–Wallis H test for statistically significant differences between multiple groups. Among the 27 selected circulating mRNA markers, all of them were found to be overexpressed (gene expression fold change > 2) in the plasma of patients from two or more CRC stages. In conclusion, NanoString-based targeted plasma CRC-associated mRNAs circulating the marker panel that can significantly distinguish CRC patients from a healthy population were developed for the non-invasive diagnosis of CRC using peripheral blood samples.
... Other kits use PCR to detect the genetic material of the virus. These methods are based on different principles and can give different results [11,12]. ...
Objectives
All countries have been deeply affected by the coronavirus disease 2019 pandemic, both economically and in situations that strain health systems, such as workforce and workload. Therefore, various measures should be taken to control the disease and prevent its spread. Since the disease onset, real-time PCR tests have been used as the gold standard for disease diagnosis. Owing to the rapid progress of the pandemic and the spread of the disease, validation, consistency, and optimization tests of some commercial kits have been conducted directly in the field. Therefore, it is important to compare the results of these kits and improve the existing ones.
Methods
We compared five kits (Bioexen, Polgen, Coronex, Diagen, and Anatolia) donated to the TOBB Economics and Technology University Hospital PCR laboratory with the KrosGen kit to detect severe acute respiratory syndrome coronavirus 2. A total of 244 samples were selected and analyzed using five different severe acute respiratory syndrome coronavirus 2 PCR detection kits.
Results
Positive and negative results from the six kits were compared using the working protocols of the kits, primers, and cycle threshold (Ct) values. Five of the six kits have reliable compatibility for Ct<30 but decreases for Ct≥30. Therefore, it is important to evaluate the performance of these kits for reduced viral loads.
Conclusions
Using a suitable kit with high compatibility for Ct≥30 is important for detecting patients with a low viral load and helping prevent disease spread.
... Several prospective and retrospective studies have been conducted to evaluate the practicality of the rapid diagnostic test devices in various platforms worldwide (13)(14)(15). Some studies evaluated only a single testing device in limited sample size (16,17), whereby a few studies have investigated multiple rapid test devices simultaneously (18,19). ...
... Testing for SARS-CoV-2 nucleic acids by laboratory polymerase chain reaction (PCR) (nucleic acid testing [NAT]) is the diagnostic gold standard for COVID-19. While NAT generally suffers from higher turnaround times and more expensive reagent costs over other testing modalities (eg, COVID-19 rapid antigen tests), its higher diagnostic sensitivity remains critical for facilitating public health surveillance, infection control, and treatment as suggested by several groups including the World Health Organization (WHO), the Government of Canada, and others (1)(2)(3)(4)(5)(6)(7). ...
Background
In British Columbia (BC), self-collected saline gargle (SG) is the only alternative to health care provider (HCP)-collected nasopharyngeal (NP) swabs to detect SARS-CoV-2 in an outpatient setting by polymerase chain reaction (PCR). However, some individuals cannot perform a SG. Our study aimed to assess combined throat-bilateral nares (TN) swabbing as a swab-based alternative.
Methods
Symptomatic individuals greater than 12 years of age seeking a COVID-19 PCR test at one of two COVID-19 collection centres in Metro Vancouver were asked to participate in this study. Participants provided a HCP-collected NP sample and a self-collected SG and TN sample for PCR testing, which were either HCP observed or unobserved.
Results
Three-hundred and eleven individuals underwent all three collections. Compared against HCP-NP, SG was 99% sensitive and 98% specific (kappa 0.97) and TN was 99% sensitive and 99% specific (kappa 0.98). Using the final clinical test interpretation as the reference standard, NP was 98% sensitive and 100% specific (kappa 0.98), and both SG and TN were 99% sensitive and 100% specific (both kappa 0.99). Mean cycle threshold values for each viral target were higher in SG specimens compared to the other sample types; however, this did not significantly impact the clinical performance, because the positivity rates were similar. The clinical performance of all specimen types was comparable within the first 7 days of symptom onset, regardless of the observation method. SG self-collections were rated the most acceptable, followed by TN.
Conclusions
TN provides another less invasive self-collection modality for symptomatic outpatient SARS-CoV-2 PCR testing.
... The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in over five million global deaths [16][17][18] . SARS-CoV-2 is measured by diagnostic methods such as RT-PCR and immunosensors (ELISA assays and agglutination tests), in addition to other less common tools, including loop-mediated isothermal amplification (LAMP), clustered regularly interspaced short palindromic repeats (CRISPR), plasmonic metasensors, and electrochemical impedance spectroscopy (EIS) 7,8,[19][20][21][22] . ...
This paper introduces a novel approach for detecting the SARS-CoV-2 recombinant spike protein
combining a label free electrochemical impedimetric immunosensor with the use of purifed chicken
IgY antibodies. The sensor employs three electrodes and is functionalized with an anti-S IgY
antibody, ELISA and immunoblot assays confrmed the positive response of chicken immunized
with SARS-CoV2 S antigen. The developed immunosensor is efective in detecting SARS-CoV-2 in
nasopharyngeal clinical samples from suspected cases. The key advantage of this biosensor is its
remarkable sensitivity, and its capability of detecting very low concentrations of the target analyte,
with a detection limit of 5.65 pg/mL. This attribute makes it highly suitable for practical point-of-care
(POC) applications, particularly in low analyte count clinical scenarios, without requiring amplifcation.
Furthermore, the biosensor has a wide dynamic range of detection, spanning from 11.56 to 740 ng/
mL, which makes it applicable for sample analysis in a typical clinical setting.
... 1 − = (12) and the radius of the pinhole (Ra) can be determined from the frequency (ωmax) at which Zf″ vs. ω −1/2 plot is maximum according to the expression (13): ...
... which in turn is related to pinhole radius (R a ) and half the distance between the centers of the adjacent pinholes or pinhole separation radius (R b ) in the monolayer coated gold IDA electrode, as depicted in Scheme 1, and described by the relationship given below, Equation (12). ...
Label-free electrochemical biosensors have many desirable characteristics in terms of miniaturization, scalability, digitization, and other attributes associated with point-of-care (POC) applications. In the era of COVID-19 and pandemic preparedness, further development of such biosensors will be immensely beneficial for rapid testing and disease management. Label-free electrochemical biosensors often employ [Fe(CN)6]−3/4 redox probes to detect low-concentration target analytes as they dramatically enhance sensitivity. However, such Faradaic-based sensors are reported to experience baseline signal drift, which compromises the performance of these devices. Here, we describe the use of a mecaptohexanoic (MHA) self-assembled monolayer (SAM) modified Au-interdigitated electrode arrays (IDA) to investigate the origin of the baseline signal drift, developed a protocol to resolve the issue, and presented insights into the underlying mechanism on the working of label-free electrochemical biosensors. Using this protocol, we demonstrate the application of MHA SAM-modified Au-IDA for POC analysis of human serum samples. We describe the use of a label-free electrochemical biosensor based on covalently conjugated SARS-CoV-2 spike protein for POC detection of COVID-19 antibodies. The test requires a short incubation time (10 min), and has a sensitivity of 35.4/decade (35.4%/10 ng mL−1) and LOD of 21 ng/mL. Negligible cross reactivity to seasonal human coronavirus or other endogenous antibodies was observed. Our studies also show that Faradaic biosensors are ~17 times more sensitive than non-Faradaic biosensors. We believe the work presented here contributes to the fundamental understanding of the underlying mechanisms of baseline signal drift and will be applicable to future development of electrochemical biosensors for POC applications.
... Even the widely used and validated method, RT-PCR (Reverse Transcription -Polymerase Chain Reaction), is not entirely effective, especially in patients with low viral loads. Also, the cost of running laboratories that require expensive instruments, affirmative examinations, and trained personnel remains a significant drawback [12]. Due to the advancement and diversity of various medical imaging and CAD (Computer Aided Diagnoses) techniques, mainly in the field of radiology and oncology, AI-based models provide a quick and inexpensive means of diagnosing COVID-19 and other related diseases [13]. ...
Nowadays, current medical imaging techniques provide means of diagnosing disorders like the recent COVID-19 and pneumonia due to technological advancements in medicine. However, the lack of sufficient medical experts, particularly amidst the breakout of the epidemic, poses severe challenges in early diagnoses and treatments, resulting in complications and unexpected fatalities. In this study, a convolutional neural network (CNN) model, VGG16 + XGBoost and VGG16 + SVM hybrid models, were used for three-class image classification on a generated dataset named Dataset-A with 6,432 chest X-ray (CXR) images (containing Normal, Covid-19, and Pneumonia classes). Then, pre-trained ResNet50, Xception, and DenseNet201 models were employed for binary classification on Dataset-B with 7,000 images (consisting of Normal and Covid-19). The suggested CNN model achieved a test accuracy of 98.91 %. Then the hybrid models (VGG16 + XGBoost and VGG16 + SVM) gained accuracies of 98.44 % and 95.60 %, respectively. The fine-tuned ResNet50, Xception, and DenseNet201 models achieved accuracies of 98.90 %, 99.14 %, and 99.00 %, respectively. Finally, the models were further evaluated and tested, yielding impressive results. These outcomes demonstrate that the models can aid radiologists with robust tools for early lungs related disease diagnoses and treatment.
... This progression can lead to moderate illness with pneumonia, and in severe cases, individuals may experience dyspnea and hypoxemia, resulting in blood oxygen levels falling below the critical threshold of 94% [59,60]. The impact of the virus extends beyond the lungs and can damage other organs [61][62][63]. The pulmonary and extrapulmonary manifestations of COVID-19 are presented in Table 1. ...
Since the emergence of the coronavirus disease 2019 (COVID-19) pandemic, many lives have been tragically lost to severe infections. The COVID-19 impact extends beyond the respiratory system, affecting various organs and functions. In severe cases, it can progress to acute respiratory distress syndrome (ARDS) and multi-organ failure, often fueled by an excessive immune response known as a cytokine storm. Mesenchymal stem cells (MSCs) have considerable potential because they can mitigate inflammation, modulate immune responses, and promote tissue regeneration. Accumulating evidence underscores the efficacy and safety of MSCs in treating severe COVID-19 and ARDS. Nonetheless, critical aspects, such as optimal routes of MSC administration, appropriate dosage, treatment intervals, management of extrapulmonary complications, and potential pediatric applications, warrant further exploration. These research avenues hold promise for enriching our understanding and refining the application of MSCs in confronting the multifaceted challenges posed by COVID-19.
... According to the Centre for Evidence-Based Medicine, nasopharyngeal swab sampling is commonly used for COVID-19 infection testing [9], however, patients find it invasive and uncomfortable [10]. Other forms of human samples used in the detection of SARS-CoV-2 viral presence include stool, urine, and saliva of COVID-19infected patients [11]. However, the SARS-CoV-2 positivity rates are dependent on a multiplicity of factors including sample type with notable differences between the anatomical collection sites [12]. ...
Introduction
as a public health policy, the ongoing global coronavirus disease 2019 vaccination drives require continuous tracking, tracing, and testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diagnostic testing is important in virus detection and understanding its spread for timely intervention. This is especially important for low-income settings where the majority of the population remains untested. This is well supported by the fact that of about 9% of the Kenyan population had been tested for the virus.
Methods
this was a cross-sectional study conducted at the Kisumu and Siaya Referral Hospitals in Kenya. Here we report on the sensitivity and specificity of the rapid antigen detection test (Ag-RDT) of SARS-CoV-2 compared with the quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) using stool and nasopharyngeal swab samples. Further, the mean Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibody levels among symptomatic and asymptomatic individuals in western Kenya were evaluated.
Results
the sensitivity and specificity of Ag-RDT were 76.3% (95% CI, 59.8-88.6%) and 96.3% (95% CI, 87.3-99.5%) with a negative and positive predictive value of 85% (95% CI, 73.8%-93.0%) and 93% (95% CI, 78.6%-99.2%) respectively. There was substantial agreement of 88% (Kappa value of 0.75, 95% CI, 0.74-0.77) between Ag-RDT and nasopharyngeal swab RT-qPCR, and between stool and nasopharyngeal swab RT-qPCR results (83.7% agreement, Kapa value 0.62, 95% CI 0.45-0.80). The mean IgM and IgG antibody response to SARS-CoV-2 were not different in asymptomatic individuals, 1.11 (95% CI, 0.78-1.44) and 0.88 (95% CI, 0.65-1.11) compared to symptomatic individuals 4.30 (95% CI 3.30-5.31) and 4.16 (95% CI 3.32 -5.00).
Conclusion
the choice of an appropriate SARS-CoV-2 diagnostic, screening, and surveillance test should be guided by the specific study needs and a rational approach for optimal results.
