A SARS-CoV-2 Coronavirus Nucleocapsid Protein Antigen-Detecting Lateral Flow Assay

Inexpensive, simple, rapid diagnostics are necessary for efficient detection, treatment and mitigation of COVID‑19. Currently, the primary diagnostic tool being utilized is reverse transcription polymerase chain reaction (RT-PCR). RT-PCR delivers results with good sensitivity and excellent specificity, but is expensive, prone to access challenges and is often slowed by transport to centralized testing laboratories. Antigen-based assays are inexpensive and can be rapidly mass-produced and deployed, with lateral flow assays (LFAs) being the most common inexpensive antigen test. To date, few antigen-detecting LFAs for COVID-19 have been commercialized. Herein, we present an open source LFA using commercially available antibodies and materials for the detection of SARS-CoV-2. Using an optical reader with comparable sensitivity to a visual read, the LFA yielded a Limit of Detection (LOD) of 23 TCID₅₀/mL (95% CI of 9.1 to 37 TCID₅₀/mL), equivalent to 1.4x10⁵ copies/mL (95% CI of 5.5x10⁴ to 2.3x10⁵ copies/mL) irradiated virus in pooled nasal matrix. This LOD meets the criteria suggested by WHO for diagnosis of acute SARS-CoV-2 infection in a point of care format. A clinical evaluation and further testing is ongoing.