Construction of Non-infectious SARS-CoV-2 Replicons and Their Application in Drug Evaluation

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused a devastating pandemic worldwide.Vaccines and antiviral drugs are the most promising candidates for combating this global epidemic,and scientists all over the world have made great efforts to this end.However,manipulation of the SARS-CoV-2 should be performed in the biosafety level3 laboratory.This makes experiments complicated and time-consuming.Therefore,a safer system for working with this virus is urgently needed.Here,we report the construction of plasmid-based,non-infectious SARS-CoV-2 replicons with turbo-green fluorescent protein and/or firefly luciferase reporters by reverse genetics using transformation-associated recombination cloning in Saccharomyces cerevisiae.Replication of these replicons was achieved simply by direct transfection of cells with the replicon plasmids as evident by the expression of reporter genes.Using SARS-CoV-2 replicons,the inhibitory effects of E64-D and remdesivir on SARS-CoV-2 replication were confirmed,and the halfmaximal effective concentration(EC50)value of remdesivir and E64-D was estimated by different quantification methods respectively,indicating that these SARS-CoV-2 replicons are useful tools for antiviral drug evaluation.