SARS-CoV-2 Nucleocapsid Protein TR-FRET Assay Amenable to High Throughput Screening

Kirill Gorshkov, Desarey Morales Vasquez, Kevin Chiem, Chengjin Ye, Bruce Nguyen Tran, Juan Carlos De La Torre, Thomas Moran, Catherine Z. Chen, Luis Martinez-Sobrido, Wei Zheng

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Drug development for specific antiviral agents against coronavirus disease 2019 (COVID-19) is still an unmet medical need as the pandemic continues to spread globally. Although huge efforts for drug repurposing and compound screens have been put forth, only a few compounds are in late-stage clinical trials. New approaches and assays are needed to accelerate COVID-19 drug discovery and development. Here, we report a time-resolved fluorescence resonance energy transfer-based assay that detects the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP) produced in infected cells. It uses two specific anti-NP monoclonal antibodies conjugated to donor and acceptor fluorophores that produce a robust ratiometric signal for high throughput screening of large compound collections. Using this assay, we measured a half maximal inhibitory concentration (IC50) for remdesivir of 9.3 μM against infection with SARS-CoV-2 USA/WA1/2020 (WA-1). The assay also detected SARS-CoV-2 South African (Beta, β), Brazilian/Japanese P.1 (Gamma, γ), and Californian (Epsilon, ϵ) variants of concern (VoC). Therefore, this homogeneous SARS-CoV-2 NP detection assay can be used for accelerating lead compound discovery for drug development and for evaluating drug efficacy against emerging SARS-CoV-2 VoC.

Original languageEnglish
Pages (from-to)8-19
Number of pages12
JournalACS Pharmacology and Translational Science
Issue number1
StatePublished - 14 Jan 2022


  • SARS-CoV-2
  • assay development
  • nucleocapsid phosphoprotein
  • variants of concern


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