Fig. 3. Generation of SARS-CoV-2 VLPs using lentiviral transduction. (A) Schematic outline for the generation of cell populations and cell clones producing SARS-CoV-2 VLPs. (B) Western blot analysis of SARS-CoV-2 proteins S and N in WCLs and ultracentrifugated supernatants (UCF) from cells transduced with lentiviral vectors expressing the indicated SARS-CoV-2 proteins. SMNE1 and SMNE2 refer to differences in the amount of the S vector relative to the other vectors (see 2.4). Protein size markers are shown. This experiment is representative of two independent replicates. (C) Electron microscopy detection of SARS-CoV-2 VLPs. Shown are EM images of putative SARS-CoV-2 VLPs produced by HEK293T cells transduced with S, M, N and E. The two pictures at the top-left, and the one at the bottom-left, show particles from “SMNE1” cells, whereas the two other images are from “SMNE2” cells. Scale bar = 100 nm.