Preparation of SARS-CoV-2 VLP to study viral assembly, egress, and entry

Virus-like particles (VLPs), assembled by expressing viral structural proteins in cultured cells, exhibit similar morphology to intact viruses. SARS-CoV-2 (CoV2) VLPs would be a useful tool to safely study viral assembly, release, and entry into target cells without the biohazards of replicating virus. We evaluated three strategies for producing CoV2 VLPs: 1) minimal CoV2 VLPs, by co-expressing the four CoV2 structural proteins: Spike (S), Nucleocapsid (N), Membrane (M), and Envelope (E) in HEK293T cells, 2) influenza VLPs pseudotyped with the CoV2 S protein, and 3) chimeric VLPs expressing a chimeric CoV2 S protein consisting of the S ectodomain fused to the transmembrane and cytoplasmic tail of influenza hemagglutinin.