Comparison of a prototype SARS-CoV-2 lateral flow immunoassay with the BinaxNOW™ COVID-19 Antigen CARD
Authors: Hill Haydon J. , Uppal Timsy , Hau Derrick , Pandit Sujata G. , Arias-Umana Jose , Foster Abigail J. , Gorzalski Andrew , Pflughoeft Kathryn J. , Burnham-Marusich Amanda R. , Reed Dana E. , Gates-Hollingsworth Marcellene A. , Gumbleton Lynette , Verma Subhash C. , AuCoin David P. 
Published: September 2022

Background

Robust diagnostics, capable of detecting multiple variant of SARS-CoV-2 are necessary to mitigate the COVID-19 pandemic. In this study we directly compare the diagnostic capabilities of an LFI engineered with monoclonal antibodies (mAbs) originating from SARS-CoV-2 NP immunizations to the Abbott BinaxNOW™ COVID-19 Antigen CARD.

Methods

Here we established a library of 18 mAbs specific to SARS-CoV-2 NP and used two of these mAbs (1CV7 and 1CV14) to generate a prototype antigen-detection lateral flow immunoassay (LFI). Samples consisting of remnant RT-PCR positive patient nasopharyngeal swabs preserved in viral transport media (VTM) were tested on the 1CV7/1CV14 LFI and the commercially available BinaxNOW™ test. Assays were allowed to resolve and results were recorded by two observers.

Findings

A total of 98 remnant SARS-CoV-2 positive patient specimens were tested on both the 1CV7/1CV14 LFI and the BinaxNOW™ test. The 1CV7/1CV14 LFI detected 71 of the total 98 specimens, while the BinaxNOW™ test detected 52 of the 98 specimens. Additionally, the 1CV7/1CV14 LFI consistently detected samples with higher RT-PCR cycle threshold values than the BinaxNOW™ test.

Interpretation

The 1CV7/1CV14 LFI outperformed the BinaxNOW™ test in the detection of BA.2, BA.2.12.1, and BA.5 Omicron sub-variants when testing remnant RT-PCR positive patient nasopharyngeal swabs diluted in viral transport media. BA.1 and BA.4 detection was comparable. The data suggest that mAbs derived from SARS-CoV-2 NP can aid in a more sensitive diagnostic immunoassay for COVID-19.

Funding

The study was funded by the University of Nevada, Reno’s Research and Innovation Office, DxDiscovery, Inc. internal funds, and through AuCoin Laboratory internal funds.

Research in Context

Evidence before this study

Since the onset of the pandemic, rapid antigen tests have proven themselves to be an accessible, accurate diagnostic platform. The widespread distribution of these tests has aided in curbing the COVID-19 pandemic. Data has shown that the tests manufactured at the beginning of the pandemic, utilizing monoclonal antibodies (mAbs) isolated from severe acute respiratory syndrome coronavirus (SARS-CoV), are less sensitive at detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron and Omicron subvariants. The reduced sensitivity can lead to diagnostic escape, and possible surges in COVID-19 caseloads

Added value of this study

In this study, a total of 98 remnant RT-PCR confirmed SARS-CoV-2 positive clinical specimens were tested on both a prototype rapid antigen test in the form of a lateral flow immunoassay (LFI) (referred to as the 1CV7/1CV14 LFI) and the available Abbott BinaxNOW™ COVID-19 Antigen CARD. The 1CV7/1CV14 LFI detected markedly more specimens (71 of 98) specimens than the BinaxNOW™ test (52 of the 98).

Implications of all the available evidence

This research suggests that that the use of mAbs isolated from immunizations with protein from SARS-CoV-2 may result in a diagnostic assay that is more sensitive in detection of SARS-CoV-2 Omicron subvariants, in comparison to the existing BinaxNOW™ COVID-19 Antigen CARD.