Figure 2.

SP-A binds to hACE2 and impacts the interaction of SARS-CoV-2 RBD and hACE2. (A) Microtiter plates were coated with biotinylated hACE2 (0.2 μg/ml) and plates were then incubated with a range of SP-A concentrations (0-10 μg/ml) in the presence of 5 mM calcium or 10 mM EDTA, and the level of bound SP-A was detected as described previously. (B) SP-A (10 µg/ml) was simultaneously incubated with biotinylated hACE2 (10 µg/ml) in wells immobilized with RBD (5 µg/ml). To assess non-specific protein interaction, some wells were incubated with 10 µg/ml BSA. Statistical analysis was performed by a student’s t-test. Values are mean ± SEM (*P<0.05, **P<0.01 compared to 0 μg/ml SP-A in CaCl₂-containing group. ψψ<0.01 vs 0 μg/ml SP-A in 10 mM EDTA group while #<0.05 is the level of significance for same SP-A concentrations in 5 mM CaCl₂ vs 10 mM EDTA-containing groups.