{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T17:15:00Z","timestamp":1771521300236,"version":"3.50.1"},"reference-count":74,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2023,9,27]],"date-time":"2023-09-27T00:00:00Z","timestamp":1695772800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science Foundation","award":["1653611"],"award-info":[{"award-number":["1653611"]}]},{"name":"National Science Foundation","award":["1511720"],"award-info":[{"award-number":["1511720"]}]},{"name":"National Science Foundation","award":["1645229"],"award-info":[{"award-number":["1645229"]}]},{"name":"National Science Foundation","award":["S10 OD020053"],"award-info":[{"award-number":["S10 OD020053"]}]},{"name":"National Science Foundation","award":["P30 CA046592"],"award-info":[{"award-number":["P30 CA046592"]}]},{"name":"National Institutes of Health","award":["1653611"],"award-info":[{"award-number":["1653611"]}]},{"name":"National Institutes of Health","award":["1511720"],"award-info":[{"award-number":["1511720"]}]},{"name":"National Institutes of Health","award":["1645229"],"award-info":[{"award-number":["1645229"]}]},{"name":"National Institutes of Health","award":["S10 OD020053"],"award-info":[{"award-number":["S10 OD020053"]}]},{"name":"National Institutes of Health","award":["P30 CA046592"],"award-info":[{"award-number":["P30 CA046592"]}]},{"name":"MCubed program at the University of Michigan","award":["1653611"],"award-info":[{"award-number":["1653611"]}]},{"name":"MCubed program at the University of Michigan","award":["1511720"],"award-info":[{"award-number":["1511720"]}]},{"name":"MCubed program at the University of Michigan","award":["1645229"],"award-info":[{"award-number":["1645229"]}]},{"name":"MCubed program at the University of Michigan","award":["S10 OD020053"],"award-info":[{"award-number":["S10 OD020053"]}]},{"name":"MCubed program at the University of Michigan","award":["P30 CA046592"],"award-info":[{"award-number":["P30 CA046592"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Virus-like particles (VLPs) have been proposed as an attractive tool in SARS-CoV-2 vaccine development, both as (1) a vaccine candidate with high immunogenicity and low reactogenicity and (2) a substitute for live virus in functional and neutralization assays. Though multiple SARS-CoV-2 VLP designs have already been explored in Sf9 insect cells, a key parameter ensuring VLPs are a viable platform is the VLP spike yield (i.e., spike protein content in VLP), which has largely been unreported. In this study, we show that the common strategy of producing SARS-CoV-2 VLPs by expressing spike protein in combination with the native coronavirus membrane and\/or envelope protein forms VLPs, but at a critically low spike yield (~0.04\u20130.08 mg\/L). In contrast, fusing the spike ectodomain to the influenza HA transmembrane domain and cytoplasmic tail and co-expressing M1 increased VLP spike yield to ~0.4 mg\/L. More importantly, this increased yield translated to a greater VLP spike antigen density (~96 spike monomers\/VLP) that more closely resembles that of native SARS-CoV-2 virus (~72\u2013144 Spike monomers\/virion). Pseudotyping further allowed for production of functional alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2), and omicron (B.1.1.529) SARS-CoV-2 VLPs that bound to the target ACE2 receptor. Finally, we demonstrated the utility of pseudotyped VLPs to test neutralizing antibody activity using a simple, acellular ELISA-based assay performed at biosafety level 1 (BSL-1). Taken together, this study highlights the advantage of pseudotyping over native SARS-CoV-2 VLP designs in achieving higher VLP spike yield and demonstrates the usefulness of pseudotyped VLPs as a surrogate for live virus in vaccine and therapeutic development against SARS-CoV-2 variants.<\/jats:p>","DOI":"10.3390\/ijms241914622","type":"journal-article","created":{"date-parts":[[2023,9,27]],"date-time":"2023-09-27T07:38:46Z","timestamp":1695800326000},"page":"14622","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Pseudotyping Improves the Yield of Functional SARS-CoV-2 Virus-like Particles (VLPs) as Tools for Vaccine and Therapeutic Development"],"prefix":"10.3390","volume":"24","author":[{"given":"Andrew J.","family":"Zak","sequence":"first","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Trang","family":"Hoang","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christine M.","family":"Yee","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Syed M.","family":"Rizvi","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ponnandy","family":"Prabhu","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7970-4796","authenticated-orcid":false,"given":"Fei","family":"Wen","sequence":"additional","affiliation":[{"name":"Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,9,27]]},"reference":[{"key":"ref_1","unstructured":"(2023, July 10). 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