We considered the possibility of S1 shedding as an underlying mechanism of irreversible inactivation, analogous to premature gp120 shedding on HIV-1 Env resulting in virus inactivation . SARS-CoV-2 pseudovirus was treated with serial dilutions of either soluble ACE2 or CV-N, co-incubated for 2 hours at 37°C, and then washed once, saving the flowthrough for Western Blot evaluation. As shown, ACE2 treatment caused dose-dependent shedding of S1 recovered in the flowthrough (Figure ), but CV-N treatment did not (Figure ). Instead, S1 remained associated with the virus samples themselves even after 10 wash cycles (Figure ).