FIG 2.

Sarbecovirus RBD clade 2 infection depends on high levels of trypsin. (a) Pseudotyped particles were collected in standard viral growth medium supplemented with 2% fetal bovine serum and used to infect Huh-7 cells with increasing amounts of trypsin. (b) Pseudotyped particles were collected in serum-free formulated viral growth medium and used to infect Huh-7 cells with increasing amounts of trypsin. (c) 293T cells stably expressing human ACE2 were transfected with increasing amounts of TMPRSS2 and infected with serum-free pseudotyped particles. (d) Pseudotypes were generated with a chimeric SARS-CoV-2 spike encoding the Rs4081 RBD and used to infect. (e) BHK cells transfected with human ACE2 or empty vector, or (f) Huh-7 cells, with or without trypsin. Shown are the data from quadruplicate infections. (g to i) Caco2, 293T, or Huh-7 were pretreated with the indicated protease inhibitors and infected with pseudotyped particles, with or without trypsin. Error bars represent the corresponding mean ± SEM.