A virus-free high-throughput platform for studying coronavirus replication inhibitors

The COVID-19 crisis demonstrates our under-preparedness for the emergence of novel pandemic viruses. Because vaccine development is time consuming, antivirals are our fastest defense against new viruses. However, current SARS-CoV-2 antiviral screens require live virus experiments in a BSL3 facility. Here we propose a screening method for inhibitors of SARS-CoV-2 that can be used in a standard tissue culture setting. This method relies on the expression of the SARS-CoV-2 replicase proteins that are responsible for viral genome replication and transcription. A viral genome mimic that results in the expression of luciferase or GFP will be used as a reporter for the activity of SARS-CoV-2 replicase activity, which provides an easy, inexpensive and high-throughput read-out. We will us an available Antiviral Compound Library to start our screens. Potential hits will be validated using a cell-free in vitro assay and virus infection experiments using both conventional lung cell lines as well as the differentiated primary airway-epithelial culture system, a highly relevant ex vivo model established within our project team, limiting the need for animal experiments. Further screens will be performed together with current international industrial and academic partners In addition to screening for novel or improved drug candidates, the platform can be used for studies into how SARS-CoV-2 induces activation of the innate immune system, which plays an important role in COVID-19 disease outcome. Overall, this system will advance our antiviral strategies and understanding of COVID-19.