PT  - JOURNAL ARTICLE
AU  - Robert L. Kruse
AU  - Yuting Huang
AU  - Heather Smetana
AU  - Eric A. Gehrie
AU  - Tim K. Amukele
AU  - Aaron A.R. Tobian
AU  - Heba H. Mostafa
AU  - Zack Z. Wang
TI  - A rapid, point of care red blood cell agglutination assay for detecting antibodies against SARS-CoV-2
AID  - 10.1101/2020.05.13.094490
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.13.094490
4099  - http://biorxiv.org/content/early/2020/05/14/2020.05.13.094490.short
4100  - http://biorxiv.org/content/early/2020/05/14/2020.05.13.094490.full
AB  - 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.Competing Interest StatementR.L.K. is an inventor on a provisional patent application related to the work described in the manuscript. All other authors have no competing interests.