SARS-CoV‑2 Coronavirus Nucleocapsid Antigen-Detecting
Half-Strip Lateral Flow Assay Toward the Development of Point of Care
Tests Using Commercially Available Reagents
posted on 2020-08-05, 20:48authored byBenjamin
D. Grant, Caitlin E. Anderson, John R. Williford, Luis F. Alonzo, Veronika A. Glukhova, David S. Boyle, Bernhard H. Weigl, Kevin P. Nichols
The
SARS-CoV-2 pandemic has created an unprecedented need for rapid
diagnostic testing to enable the efficient treatment and mitigation
of COVID-19. The primary diagnostic tool currently employed is reverse
transcription polymerase chain reaction (RT-PCR), which can have good
sensitivity and excellent specificity. Unfortunately, implementation
costs and logistical problems with reagents during the global SARS-CoV-2
pandemic have hindered its universal on demand adoption. Lateral flow
assays (LFAs) represent a class of diagnostic that, if sufficiently
clinically sensitive, may fill many of the gaps in the current RT-PCR
testing regime, especially in low- and middle-income countries (LMICs).
To date, many serology LFAs have been developed, though none meet
the performance requirements necessary for diagnostic use cases, primarily
due to the relatively long delay between infection and seroconversion.
However, on the basis of previously reported results from SARS-CoV-1,
antigen-based SARS-CoV-2 assays may have significantly better clinical
sensitivity than serology assays. To date, only a very small number
of antigen-detecting LFAs have been developed. Development of a half-strip
LFA is a useful first step in the development of any LFA format. In
this work, we present a half-strip LFA using commercially available
antibodies for the detection of SARS-CoV-2. We have tested this LFA
in buffer and measured an LOD of 0.65 ng/mL (95% CI of 0.53 to 0.77
ng/mL) ng/mL with recombinant antigen using an optical reader with
sensitivity equivalent to a visual read. Further development, including
evaluating the appropriate sample matrix, will be required for this
assay approach to be made useful in a point of care setting, though
this half-strip LFA may serve as a useful starting point for others
developing similar tests.