A rapid, point of care red blood cell agglutination assay for detecting antibodies against SARS-CoV-2

Abstract

The COVID-19 pandemic has brought the world to a halt, with cases observed around the globe causing significant mortality. There is an urgent need for serological tests to detect antibodies against SARS-CoV-2, which could be used to assess the prevalence of infection, as well as ascertain individuals who may be protected from future infection. Current serological tests developed for SARS-CoV-2 rely on traditional technologies such as enzyme-linked immunosorbent assays (ELISA) and lateral flow assays, which may lack scalability to meet the demand of hundreds of millions of antibody tests in the coming year. Herein, we present an alternative method of antibody testing that just depends on one protein reagent being added to patient serum/plasma or whole blood and a short five-minute assay time. A novel fusion protein was designed that binds red blood cells (RBC) via a single-chain variable fragment (scFv) against the H antigen and displays the receptor-binding domain (RBD) of SARS-CoV-2 spike protein on the surface of RBCs. Upon mixing of the fusion protein, RBD-scFv with recovered COVID-19 patient serum and RBCs, we observed agglutination of RBCs, indicating the patient developed antibodies against SARS-CoV-2 RBD. Given that the test uses methods routinely used in hospital clinical labs across the world, we anticipate the test can be rapidly deployed with only the protein reagent required at projected manufacturing cost at U.S. cents per test. We anticipate our agglutination assay may find extensive use in low-resource settings for detecting SARS-CoV-2 antibodies. was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.

A haemagglutination test for rapid detection of antibodies to SARS-CoV-2

“…We have adapted this approach to detection of antibodies to SARS-CoV-2 by linking the RBD of the SARS-CoV-2 spike protein to IH4 via a short (GSG)2 linker to produce the fusion protein IH4-RBD-6H ( Figure 1). Since we embarked on this project, another group has described preliminary results with an approach similar to ours, but using a fusion of the RBD to an ScFV against the H antigen to coat red blood cells with the SARS-2 RBD (Kruse et al, 2020).…”

A haemagglutination test for rapid detection of antibodies to SARS-CoV-2

“…1). Since we embarked on this project, another group has described preliminary results with an approach similar to ours, but using a fusion of the RBD to an scFv against the H antigen to coat red blood cells with the SARS-2 RBD 23 .…”

A Recent Update on Advanced Molecular Diagnostic Techniques for COVID-19 Pandemic: An Overview

“…The agglutination test was performed by mixing the fusion protein with red blood cells and the serum of a patient recovered from COVID-19 (specimen collected at least 28 days post symptoms and a negative PCR test upon discharge). Optimal agglutination was achieved at the highest fusion protein concentration, i.e., 100% within 5 min of incubation ( 45 ).…”