ACE2 and infection: As shown in Figures 4A–E, A549-ACE2 cells, at day 4 post-infection (p.i.)of SARS-CoV-2, had dramatically induction of tRF5-GluCTC, tRF5-LysCTT, tRF5-ValCAC, tRF5-CysGCA, and tRF5-GlnCTG.