An infectious cDNA clone of SARS-CoV-2

The ongoing pandemic of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), underscores the urgency to develop experimental systems for studying this virus and identifying countermeasures. We report a reverse genetic system for SARS-CoV-2. Seven cDNA fragments spanning the SARS-CoV-2 genome were assembled into a full-genome cDNA. RNA transcribed from the full-genome cDNA was highly infectious after electroporation into cells, producing 2.9×106 PFU/ml of virus. Compared with a clinical isolate, the infectious clone-derived SARS-CoV-2 (icSARS-CoV-2) exhibited similar plaque morphology, viral RNA profile, and replication kinetics. Additionally, icSARS-CoV-2 retained engineered molecular markers and did not acquire other mutations. A stable mNeonGreen SARS-CoV-2 (icSARS-CoV- 2-mNG) was generated by introducing this reporter gene into OFR7 of the viral genome. icSARSCoV- 2-mNG was successfully used to evaluate the antiviral activities of interferon. Collectively, the reverse genetic system and reporter virus provide key reagents to study SARS-CoV-2 and develop countermeasures.