Fig. 1.
Preparation and characterization of EBs derived from SARS-CoV-2 spike protein (S)-expressing DC2.4 cells. A) Lentiviral transduction of DC2.4 cells for S expression, followed by blebbing and vaccination of the syngeneic mice. Briefly, DC2.4 cells were transduced with S-expressing lentivirus prior to puromycin selection. DC2.4 S cells were then treated with blebbing buffer to produce EBs. The micro-sized EBs were isolated by centrifugation and used to vaccinate the animals, followed by assays for antibody binding to S and neutralization of S-pseudotyped virus. B) DC2.4 cells, DC2.4 S cells, DC2.4 EBs, and DC2.4 S EBs were analyzed for S expression by flow cytometry. C) 2.5 × 105 DC2.4 S cells and DC2.4 S EBs at a surface area equivalent to 2.5 × 105 DC2.4 S cells were lysed, and their S contents were quantified by ELISA.