Figure 11.

Evaluation of receptors interacting with the SARS-CoV-2 S1 spike protein by an indirect ELISA. Recombinant SARS-CoV-2 S1-His protein was incubated with bound ACE2, DPP4, FGFR3, NRP1, or BSA protein in triplicate wells for 1 h at 37 °C. The wells were incubated with a rabbit anti-SARS-CoV-2 spike IgG and an HRP-conjugated goat anti-rabbit IgG for 1 h at 37 °C. Signal was produced using a TMB substrate and endpoint absorbance at 450 nm was measured after a 30-min incubation. Mean endpoint absorbances for recombinant protein receptors were compared to the means of an unrelated BSA control using a Dunnett’s test with statistically significant differences (p < 0.05) indicated with a star.