The Evolution of COVID-19 Diagnostics
Debmalya Barh, Kenneth Lundstrom in COVID-19, 2022
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].
Fasciola and Fasciolosis
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
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
Understanding the Role of Existing Technology in the Fight Against COVID-19
Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma in Pandemic Detection and Analysis Through Smart Computing Technologies, 2022
The use of biosensors for the rapid detection of coronavirus has also been discussed by several researchers, which will be discussed in this section. A biosensor is a device which uses a transducer and a biological matter such as enzymes, nucleic acids, or antibodies to detect the presence of the substance under investigation. The testing material (analyte) reacts with the biological matter, causing a certain change (for example, resistance) that is converted into an electrical signal by the transducer (Figure 2.6). Various chip-based and paper-based biosensors are envisioned to be helpful for rapid diagnosis of viral infections [23]. The advantages of these biosensors are their low cost, fast testing speed, and simple operational procedure. These biosensors are based on the detection of nucleic acids, antigens, or antibodies from various samples such as blood, saliva, sputum, and nasal secretion [24–26]. The chip-based biosensors are commonly made using polydimethylsiloxane (PDMS) or poly(methyl methacrylate) (PMMA) [27, 28]. The chip-based biosensors involve multiple channels for automated extraction of nucleic acid and isothermal amplification. Further components for real-time signal detection are based on fluorescence, colorimetry, or electrochemical detection [23]. The paper-based biosensors are gaining more interest than chip-based because of several advantages they offer. The paper-based sensors are biodegradable, have lower cost, are easy to fabricate and chemically modify [29–31]. The lateral flow test strips have been put to test for COVID-19 detection. They detect the antibodies in the patient sample [24, 26].
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.
Low sensitivity of a-defensin (Synovasure) test for intraoperative exclusion of prosthetic joint infection
Published in Acta Orthopaedica, 2018
Ruben Scholten, Jetze Visser, Job L C Van Susante, Corné J M Van Loon
In contrast to these earlier studies our study focused on the ability of the Synovasure test to exclude PJI in a uniform subgroup of patients undergoing revision surgery for suspected early aseptic loosening. To our knowledge, this is the first study to assess the Synovasure lateral flow test in this specific homogeneous subgroup of patients. From clinical practice this is an important strength of our study and as such is the finding of a rather low sensitivity in this particular subgroup. This strength has to be balanced against the limitation of a rather small number of patients included, which warrants caution in drawing firm conclusions. Another strength of our study, and that of Sigmund et al. (2017), is that there is no conflict of interest in relation to the manufacturer of the Synovasure test.
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