Column Agglutination Assay Using Polystyrene Microbeads for Rapid Detection of Antibodies against SARS-CoV-2

Abstract

Rapid serology platforms are essential in disease pandemics for a variety of applications, including epidemiological surveillance, contact tracing, vaccination monitoring, and primary diagnosis in resource-limited areas. Laboratory-based enzymelinked immunosorbent assay (ELISA) platforms are inherently multistep processes that require trained personnel and are of relatively limited throughput. As an alternative, agglutination-based systems have been developed; however, they rely on donor red blood cells and are not yet available for high-throughput screening. Column agglutination tests are a mainstay of pretransfusion blood typing and can be performed at a range of scales, ranging from manual through to fully automated testing. Here, we describe a column agglutination test using colored microbeads coated with recombinant SARS-CoV-2 spike protein that agglutinates when incubated with serum samples collected from patients recently infected with SARS-CoV-2. After confirming specific agglutination, we optimized centrifugal force and time to distinguish samples from uninfected vs SARS-CoV-2-infected individuals and then showed concordant results against ELISA for 22 clinical samples, and also a set of serial bleeds from one donor at days 6−10 postinfection. Our study demonstrates the use of a simple, scalable, and rapid diagnostic platform that can be tailored to detect antibodies raised against SARS-CoV-2 and can be easily integrated with established laboratory frameworks worldwide.

Selective Detection and Ultrasensitive Quantification of SARS-CoV-2 IgG Antibodies in Clinical Plasma Samples Using Epitope-Modified Nanoplasmonic Biosensing Platforms

“…Serological assays that have been developed for COVID-19 detection include techniques based on enzyme-linked immunosorbent assays (ELISA), chemiluminescent assays, lateral flow assays, and others. 4 − 6 , 10 , 12 − 16 However, these techniques either suffer from low sensitivity when quantifying a low abundance of biomarkers, especially at a high specificity, 5 , 9 , 12 , 15 , 16 or are unable to differentiate immunoglobulin-G (IgG) specific to SARS-CoV-2 from other novel coronaviruses. 14 …”

“…A highly specific serology antibody assay for COVID-19 must include a receptor molecule that is a subset of the SARS-CoV-2 spike protein and a detection analyte that would be SARS-CoV-2 neutralizing antibody (IgG). 10 , 15 , 26 , 27 Recent works by Ng and co-workers showed that around 18 peptides in length of the spike protein segments, called linear epitopes, have a higher binding affinity toward SARS-CoV-2 neutralizing antibody IgG, suggesting a further improvement in specificity. 9 , 26 The authors reported a gold nanoparticle-based colorimetric assay to detect IgG from clinical samples.…”

“…Therefore, crucial information such as time of exposure, disease progression, and past infection or immunity can be obtained by measuring the antibody level in biofluids (serology antibody assay). ,− Additionally, the level of antibodies can provide insights into the human immune response by determining the level of protection the body has against the virus. Serological assays that have been developed for COVID-19 detection include techniques based on enzyme-linked immunosorbent assays (ELISA), chemiluminescent assays, lateral flow assays, and others. − ,,− However, these techniques either suffer from low sensitivity when quantifying a low abundance of biomarkers, especially at a high specificity, ,,,, or are unable to differentiate immunoglobulin-G (IgG) specific to SARS-CoV-2 from other novel coronaviruses …”

“…Therefore, blocking this binding could prevent the viruses’ entry. ,,, Neutralizing antibodies that are produced against the spike protein have been shown to target RBD and prevent cellular transfusion. A highly specific serology antibody assay for COVID-19 must include a receptor molecule that is a subset of the SARS-CoV-2 spike protein and a detection analyte that would be SARS-CoV-2 neutralizing antibody (IgG). ,,, Recent works by Ng and co-workers showed that around 18 peptides in length of the spike protein segments, called linear epitopes, have a higher binding affinity toward SARS-CoV-2 neutralizing antibody IgG, suggesting a further improvement in specificity. , The authors reported a gold nanoparticle-based colorimetric assay to detect IgG from clinical samples. Although this colorimetric-based IgG detection is highly specific, the assay displayed a limit of detection (LOD) in the nanomolar (nM) range.…”

Magnetic nanoparticles coated with zwitterionic copolymer as an advanced material for rapid and instrument-free biomolecular detection in human serum

“…The aggregation of particles via specific interactions between complementary biological components has gained increasing attention in medical diagnosis due to its simplicity, practicality, and low cost [7][8][9][10][11][12][13][14][15][16]. Traditionally, agglutination assays based on polystyrene nanoand microspheres, well-known as the latex agglutination test, have been extensively used.…”