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Detection Technology
Published in Rick Houghton, William Bennett, Emergency Characterization of Unknown Materials, 2020
Rick Houghton, William Bennett
Enzyme-Linked Immunosorbent Assay (ELISA) uses an enzyme step to amplify results (Figure 3.50). ELISA is a sensitive biochemical technique used to detect the presence of specific substances, such as enzymes, viruses, or bacteria in a sample. ELISA is based on the concept of antigen-antibody complex with two antibodies and an indicator, usually an enzyme and a dye. The first antibody is specific to the antigen in the sample. The indicator is another antibody linked to an enzyme that reacts with the antigen-antibody complex or an intermediate antibody. The antigen-antibody/antibody-enzyme complex produces a change in color or fluorescence from a previously invisible substance to indicate a positive result. The enzyme acts as an amplifier to the color or fluorescence because only a few bound complexes will produce many signal molecules through catalytic action. There are minor variations on this procedure. ELISA tests are time dependent.
Molecular Analysis of Immunity
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Molecular analysis of the titer, specificity and isotype of an antibody present within serum may all be performed using the enzyme-linked immunosorbent assay (ELISA).142-145 The principle of ELISA is relatively simple. The antigen against which specific antibodies are being measured is bound to wells in plastic plates. Serum at different dilutions is then added to the wells and incubated until binding reaches equilibrium (usually about 30 mins). The presence of antigen-bound specific antibody is detected using a secondary layer of monoclonal antibodies specific for one of Ig isotypes. This secondary layer antibody is conjugated to an enzyme such as horseradish peroxidase or alkaline phosphatase, which then reacts with an added substrate to produce a colored soluble product, the intensity of which is measured by light absorbance and which is proportional to the amount of antigen-specific antibody present in serum. The serial dilution of serum at which binding falls to 50% of the maximum is referred to as the ‘titer’ of that antibody in serum. Thus, the result of the ELISA measures the amount and isotype of antibodies specific for a particular antigen in serum. This type of molecular analysis forms the basis of the assessment of immune reconstitution of B cell function in situations of lymphopenia such as HIV infection146,147 or after chemotherapy148,149 Furthermore, it forms a crucial part of the assessment of antigen-specific immunity after immunization.139-141
Experimental Protocols for Generation and Evaluation of Articular Cartilage
Published in Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi, Articular Cartilage, 2017
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi
Multiple types of ELISA are available, including standard, sandwich, and competitive. Presented in this protocol are the classic standard ELISA and the sandwich ELISA. While the sandwich ELISA has better substrate specificity and sensitivity, it requires multiple primary antibodies directed against the target, which may not be readily available for all targets.
Application of Artificial Intelligence on Post Pandemic Situation and Lesson Learn for Future Prospects
Published in Journal of Experimental & Theoretical Artificial Intelligence, 2023
Priyanka Dwivedi, Achintya Kumar Sarkar, Chinmay Chakraborty, Monoj Singha, Vineet Rojwal
As discussed, earlier CoV-2 has several proteins like spike (S), nucleoprotein (N), envelope protein, glycoprotein, membrane matrix protein etc. These proteins can also be used for antigens to detect it. Among all the proteins S and N proteins are mostly used as antigen-based detection. Similar to antigen, antibodies like immunoglobulin M (IgM) and immunoglobulin G (IgG) are effective to determine the virus using enzyme linked immunosorbent assay (ELISA) method (Xiang et al., 2020). ELISA is an enzyme-based detection method. But the ELISA method is a time-consuming process. To shorten the diagnostics time, loop-mediated isothermal amplification (LAMP) is used (Yu et al., 2020). Though these processes are reliable and able to diagnose the virus, it has some drawbacks like it is a time-consuming process or the microchip is not available in sufficient amounts. Therefore, there is a need for technology to shorten the processing time or use alternative methods for diagnostic purposes.
Room-temperature-storable chemiluminescence freeze-drying mixes for detection of SARS-CoV-2 neutralizing antibody
Published in Drying Technology, 2022
Qihan Zhang, Liuyu Gong, Yewei Zhang, Ya Shen, Lin Shen, Liangli Cao, Guocheng Han, Fangrong Hu, Feijun Zhao, Zhencheng Chen
Enzyme-linked immunosorbent assay (ELISA) is widely used for neutralizing antibody test by using active protein (antibody or antigen).[7,8] But the ELISA kit has several disadvantages, such as low temperature storage, poor repeatability, poor accuracy, low degree of automation.[9,10] Chemiluminescence (Luminescence) is currently the most applied clinical analysis due to its advantages of no radioactive waste, simple instrument requirements, low detection limit and a wide dynamic range.[11–13] However, both ELISA kit and Luminescence kit have a critical disadvantage which needs to be low temperature storage and cold-chain transportation.[14] Hence, a new storage strategy should be developed for clinical analysis of SARS-CoV-2 neutralization with such characteristics as stable, sensitive, and dispersible at room temperature.
Role of S&T organisations in mitigation of Covid-19: CSIR as a case study
Published in Indian Chemical Engineer, 2020
Geetha Vani Rayasam, Shekhar C. Mande
The success of the surveillance strategy depends on the methods used for the detection of viral infection. The accepted ‘gold standard’ technology for detection globally is Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) which is sensitive and specific. The drawback is that it is expensive, time-consuming and needs specialised instrumentation and training. Another technique often used is antibody-based testing which could be either ELISA based or lateral flow-based method. While the latter can be used at the point of care it is less sensitive. The readouts of RT-PCR indicates whether the patient is infected, whereas the antibody test indicates that the subject has been exposed to the virus and elicited an immune response. Currently, the understanding of the protection offered by the antibodies against subsequent infections is limited. However, protection may likely last for a few months and the concept of ‘immunity passport’ is being examined globally. However, much more research is needed in understanding the variability of the symptoms in patients and the extent of protection provided by the immune response in recovered patients.