Fig. 2.

sACE2 acts as receptor binding SARS-CoV glycoprotein S pseudotyped FIV virus and blocks virus infection of target cells. A: schematic representation of chimeric and alanine substitution mutant of human ACE2. ACE2-SEC comprises the full ACE2 ectodomain (residues 1-740) and the human β-defensin-2 peptide (hBD2, residues 1-45); ACE2-ΔRBD contains full-length ACE2 residues but has alanine substitutions at residues 31, 41, 82–84, 353, 355, and 357. B: immunoblot immunodetection of cell-associated and sACE2 from HEK293 cells transfected with indicated expression vectors. C: β-galactosidase activity indicates SARS-CoV S protein pseudotyped FIV transduction efficiency in transfected cells. HEK293 cells were transfected with expression vectors. Forty eight hours later S protein pseudotyped FIV was added for 4 h and cells incubated at 37°C for 48 h, followed by measurement of β-galactosidase activity (normalized to luciferase transfection control). Data are means ± SE for triplicate samples in each group.