ACE2 and infection: We also performed a time-course infection experiment by using a transcription- and replication-competent SARS-CoV-2 virus-like particle system (SARS-CoV-2 GFP/ΔN trVLP), which enables the complete viral life cycle in HEK293T-ACE2 cells expressing the SARS-CoV-2 nucleocapsid protein (43).