Fig. 4. Generation of cell clones stably producing SARS-CoV-2 VLPs. (A) Western blot analysis of SARS-CoV-2 proteins S and N present in ultracentrifugated supernatants of 22 cell clones derived from HEK293T cells transduced with S, M, N and E (“SMNE2” cells) as shown in Fig. 3. Protein size markers are shown. (B) Morphological analysis of SARS-CoV-2 VLPs. Shown are EM images of putative SARS-CoV-2 VLPs found in the supernatants of HEK293T clones (from left to right: 1-22, 1-16, 2-13, 2-7). Scale bar = 100 nm.