FURIN and infection: ppVSVΔG-G and ppVSVΔG-SARS-CoV-2 S particles must be produced in HEK 293T cells, and infection assays with ppVSVΔG-SARS-CoV-2 S in Vero E6 or ACE2- and Furin-transfected HEK 293T cells are suggested.