CD209 and infection: To ascertain the effect of the M, N, and E proteins on DC-SIGN-mediated trans-infection, four viral strains were produced: three had one additional structural protein incorporated in the SARS-CoV-2 nCoV-19 Wuhan Wild-Type lentiviral particle (either M, N, or E protein) (Figure S6A,B), and a final strain was produced with all three structural proteins included with the lentiviral system (Figure S6C).