Unlike CD4, which inhibits HIV-1 infection at high concentration46, but promotes infection at low concentration47, both hACE2-Fc WT and mutant did not promote infection over a wide range of concentrations (hACE2-Fc WT, mutant: 0.002 × IC50–10 × IC50) (Fig. 2g). This evidence concerns the gene CD4 and HIV-1 infection.