scholarly journals Antigen production and development of an indirect ELISA based on the nucleocapsid protein to detect human SARS-CoV-2 seroconversion

Author(s):  
Marcelo S. Conzentino ◽  
Karl Forchhammer ◽  
Emanuel M. Souza ◽  
Fábio O. Pedrosa ◽  
Meri B. Nogueira ◽  
...  
2021 ◽  
Author(s):  
Marcelo S. Conzentino ◽  
Karl Forchhammer ◽  
Emanuel M Souza ◽  
Fábio O. Pedrosa ◽  
Meri B. Nogueira ◽  
...  

AbstractSerological assays are important tools to identify previous exposure to SARS-CoV-2, helping to track COVID-19 cases and determine the level of humoral response to SARS-CoV-2 infections and/or immunization to future vaccines. Here the SARS-CoV-2 nucleocapsid protein was expressed in Escherichia coli and purified to homogeneity and high yield using a single chromatography step. The purified SARS-CoV-2 nucleocapsid protein was used to develop an indirect enzyme-linked immunosorbent assay for the identification of human SARS-CoV-2 seroconverts. The assay sensitivity and specificity were determined analyzing sera from 140 PCR-confirmed COVID-19 cases and 210 pre-pandemic controls. The assay operated with 90% sensitivity and 98% specificity; identical accuracies were obtained in head-to-head comparison with a commercial ELISA kit. Antigen coated plates were stable for up to 3 months at 4°C). The ELISA method described is ready to mass production and will be an additional toll to track COVID-19 cases.


2021 ◽  
Author(s):  
David Cate ◽  
Helen Hsieh ◽  
Veronika Glukhova ◽  
Joshua D Bishop ◽  
H Gleda Hermansky ◽  
...  

<p></p><p>The global COVID-19 pandemic has created an urgent demand for large numbers of inexpensive, accurate, rapid, point-of-care diagnostic tests. Analyte-based assays are suitably inexpensive and can be rapidly mass-produced, but for sufficiently accurate performance they require highly optimized antibodies and assay conditions. We used an automated liquid handling system, customized to handle arrays of lateral flow immunoassay (LFA) tests in a high-throughput screen, to identify anti-nucleocapsid antibodies that will perform optimally in an LFA. We tested 1021 anti-nucleocapsid antibody pairs as LFA capture and detection reagents with the goal of highlighting pairs that have the greatest affinity for unique epitopes of the nucleocapsid protein of SARS-CoV-2 within the LFA format. In contrast to traditional antibody screening methods (e.g., ELISA, bio-layer interferometry), the method described here integrates real-time reaction kinetics with transport in, and immobilization directly onto, nitrocellulose. We have identified several candidate antibody pairs that are suitable for further development of an LFA for SARS-CoV-2.</p><p></p>


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