TMPRSS2 and infection: Pre-treatment of cells with 10 μM mα-DGN blocked infection of VeroE6-TMPRSS2 cells with SARS-CoV-2 ancestral strain, Gamma, Delta, Omicron BA.1 and Omicron BA.4 by 80.4, 61.7, 86.4, 84.3 and 82.7 % respectively (Fig. 2A–E and F).