ACE2 and COVID-19: To further determine whether NhPV or Suramin is targeting the interaction ofSARS-CoV2-SP and its receptor, ACE2, we used an in vitroSARS-CoV2-SP/ACE2 binding ELISA assay, as described in Materials and methods.Additionally, an anti-COVID-19 neutralizing antibody (SAD-S35) [39] was included inparallel.