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The Evolution of COVID-19 Diagnostics
Published in Debmalya Barh, Kenneth Lundstrom, COVID-19, 2022
Praveen Rai, Ballamoole Krishna Kumar, Deekshit Vijaya Kumar, Prashant Kumar, Anoop Kumar, Shashi Kumar Shetty, Biswajit Maiti
Point-of-care (POC) serological assays are simple and rapid tests based on lateral flow immunoassay (LFIA) technology. The primary advantage of these assays is their simplicity, with a time-to-result anywhere between 10 and 30 minutes. A typical lateral flow test strip is made of overlapping membranes mounted on a backing card. When a sample is added to the lateral flow, it migrates through the conjugate pad, which includes antibodies unique to the target analyte that has been conjugated to colored or fluorescent particles. The analyte-bound conjugated antibody then flows through the immobilized antibody in a test and control line of the nitrocellulose membrane. The read-out, represented by the lines appearing with different intensities, can be assessed by eye or by using a dedicated reader. The utility of low-cost, rapid, and accurate POC tests prompted the development and marketing of several lateral flow immunoassays for the diagnosis of COVID-19. However, the study by Bastos et al. [54] raised concerns about detection sensitivity of the commercially available lateral immunoassays as they demonstrated the pooled sensitivity of 66% in detecting COVID-19 cases [54].
Histoplasma capsulatum
Published in Rossana de Aguiar Cordeiro, Pocket Guide to Mycological Diagnosis, 2019
Rosely Maria Zancopé-Oliveira, Claudia Vera Pizzini, Marcos de Abreu Almeida, Rodrigo de Almeida Paes
Nowadays, a lateral flow test for Histoplasma antigen detection is also under development by IMMY, and in the future, it will be of possible use as point-of-care diagnosis for histoplasmosis, as it is available for cryptococcosis.
Fasciola and Fasciolosis
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Antonio Muro, Jose Rojas-Caraballo
The antibodies produced against the antigens of F. hepatica have high sensitivity, and can be diagnosed even in the acute phase of the disease. ELISA assay is used, with antigens from F. hepatica, mainly excretory-secretory antigens,53,54 cathepsin L1,55,56 proteins from the tegument,57 saposin-like proteins,58 leucine aminopeptidase,59 and other recombinant antigens.60 Although there are several antigens for such detection, cathepsins remain the main source of antigens for the detection of circulating antibodies.61 Monoclonal antibodies have also been used for the detection of antigens in sera samples and also for the detection of coproantigens. Some examples of monoclonal antibodies currently used are ES78 and MM3.62,63 A new lateral flow test was constructed with a recombinant cathepsin L1, using protein A and MM3 monoclonal antibodies as detector reagents.64
Antibody engineering and its therapeutic applications
Published in International Reviews of Immunology, 2023
Divya Kandari, Rakesh Bhatnagar
Abs are versatile, specific and sensitive molecules, which have significantly contributed to research areas such as pathology, microbiology and diagnostics for infectious pathogens/metabolic disorders, for their timely treatments. Specific Ab-based techniques or immunoassays assistive in developing diagnostics or in research purposes are (a) ELISA, (b) western blot, (c) immunohistochemistry, (d) immunoprecipitation (IP), (e) Co-IP, (f) FACS, (g) enzyme-linked immunospot, (h) lateral flow test, (i) flow cytometry and (j) mass spectrometry. The diagnostic imaging techniques require Abs against a specific target Ags, which can either be novel Abs or any existing FDA-approved Ab is repurposed through conjugation with an imaging probe through AET. The latter approach is preferable because of the lesser safety concerns in human application. Additionally, Abs are present in biosensors, nanobiosensors for specific detection of pathogens or any pathogenic condition in the host.170
Rapid lateral flow tests for the detection of SARS-CoV-2 neutralizing antibodies
Published in Expert Review of Molecular Diagnostics, 2021
Jianfu J. Wang, Nan Zhang, Sarah A. Richardson, Jin V. Wu
A lateral flow test typically uses antibody–antigen interaction as test principle like other immunoassays. Usually, higher antibody affinity results in higher assay sensitivity. High-affinity antibody to an antigen can be obtained through modern antibody development technologies nowadays. Antibody production cost can be well managed with available mature manufacturing processes. Protein–protein interaction without antibody can also be used in lateral flow test[37]. However, it is quite rare, simply because the binding affinity between proteins is usually much lower than that between an antibody and an antigen and is impossible to increase. Lower binding affinity or lower assay sensitivity often leads to much longer assay time and use of high sensitivity detection system, such as fluorescent labeling and fluorescence detection instrument[37]. Manufacturing cost of a recombinant protein is usually much higher than that of an antibody.
Current and emerging trends in point-of-care urinalysis tests
Published in Expert Review of Molecular Diagnostics, 2020
Rongwei Lei, Rannon Huo, Chandra Mohan
A brief working principle and general structure of the LFA is summarized below and detailed elsewhere [15,27,37]. A typical lateral flow test strip is composed of four overlapping elements that are mounted on an adhesive backing. The first element is the sample pad, which is typically made of cellulose or glass fiber to consistently deliver the sample of interest to the second element, which is the conjugate pad. The conjugate pad can be made of cellulose, glass fiber, or polyesters depending on the labeled conjugates and the sensitivity of the assay. The labeled biomolecules are held in the conjugate pad and should bind to the analyte in the sample of interest when the sample of interest reaches the conjugate pad. The analyte-conjugate complex then flows through the third element, which is the nitrocellulose membrane where specific biological compounds (typically antibody, protein, or nucleic acids) are immobilized at pre-defined lines. The analyte, analyte-conjugate complex, and conjugates should react specifically to the compounds dispensed on the membrane. Lastly, any remaining sample of interest should be absorbed by the fourth element, which is the absorbent pad.