{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,24]],"date-time":"2025-11-24T12:46:08Z","timestamp":1763988368455,"version":"build-2065373602"},"reference-count":25,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2022,11,8]],"date-time":"2022-11-08T00:00:00Z","timestamp":1667865600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"],"award-info":[{"award-number":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"],"award-info":[{"award-number":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]},{"name":"CAMS Innovation Fund for Medical Sciences","award":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"],"award-info":[{"award-number":["No. 31972719","No. 2021YFD1801103-6","2020-12M-5-001"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>The pandemic of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed great threat to the world in many aspects. There is an urgent requirement for an effective preventive vaccine. The receptor binding domain (RBD), located on the spike (S) gene, is responsible for binding to the angiotensin-converting enzyme 2 (ACE2) receptor of host cells. The RBD protein is an effective and safe antigen candidate. The six-helix bundle (6HB) \u201cmolecular clamp\u201d is a novel thermally-stable trimerization domain derived from a human immunodeficiency virus (HIV) gp41 protein segment. We selected the baculovirus system to fuse and express the RBD protein and 6HB for imitating the natural trimeric structure of RBD, named RBD-6HB. Recombinant RBD-6HB was successfully obtained from the cell culture supernatant and purified to high homogeneity. The purity of the final protein preparation was more than 97%. The results showed that the protein was identified as a homogeneous polymer. Further studies showed that the RBD-6HB protein combined with AL\/CpG adjuvant could stimulate animals to produce sustained high-level antibodies and establish an effective protective barrier to protect mice from challenges. Our findings highlight the importance of trimerized SARS-CoV-2 S protein RBD in designing SARS-CoV-2 vaccines and provide a rationale for developing a protective vaccine through the induction of antibodies against the RBD domain.<\/jats:p>","DOI":"10.3390\/ijms232213716","type":"journal-article","created":{"date-parts":[[2022,11,8]],"date-time":"2022-11-08T08:17:12Z","timestamp":1667895432000},"page":"13716","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["A Vaccine of SARS-CoV-2 S Protein RBD Induces Protective Immunity"],"prefix":"10.3390","volume":"23","author":[{"given":"Qiaoqiao","family":"Qu","sequence":"first","affiliation":[{"name":"State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530004, China"},{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pengfei","family":"Hao","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wang","family":"Xu","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Letian","family":"Li","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuhang","family":"Jiang","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiqiang","family":"Xu","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jing","family":"Chen","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zihan","family":"Gao","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhaoxia","family":"Pang","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ningyi","family":"Jin","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3267-1859","authenticated-orcid":false,"given":"Chang","family":"Li","sequence":"additional","affiliation":[{"name":"Research Unit of Key Technologies for Prevention and Control of Virus Zoonoses, Chinese Academy of Medical Sciences, Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun 130122, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,11,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"967493","DOI":"10.3389\/fcimb.2022.967493","article-title":"Immunogenicity and protective potential of chimeric virus-like particles containing SARS-CoV-2 spike and H5N1 matrix 1 proteins","volume":"12","author":"Chen","year":"2022","journal-title":"Front. Cell. Infect. Microbiol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1038\/s41580-021-00418-x","article-title":"Mechanisms of SARS-CoV-2 entry into cells","volume":"23","author":"Jackson","year":"2022","journal-title":"Nat. Rev. Mol. Cell Biol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"587269","DOI":"10.3389\/fcimb.2020.587269","article-title":"SARS-CoV-2: Structure, Biology, and Structure-Based Therapeutics Development","volume":"10","author":"Wang","year":"2020","journal-title":"Front. Cell. Infect. Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1038\/s41586-020-2180-5","article-title":"Structure of the SARS-CoV-2 spike receptor-binding domain bound to the ACE2 receptor","volume":"581","author":"Lan","year":"2020","journal-title":"Nature"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2832","DOI":"10.1016\/j.vaccine.2006.10.031","article-title":"Receptor-binding domain of SARS-CoV spike protein induces long-term protective immunity in an animal model","volume":"25","author":"Du","year":"2007","journal-title":"Vaccine"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1016\/j.ijbiomac.2021.08.232","article-title":"Mucosal IgA response elicited by intranasal immunization of Lactobacillus plantarum expressing surface-displayed RBD protein of SARS-CoV-2","volume":"190","author":"Li","year":"2021","journal-title":"Int. J. Biol. Macromol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"572","DOI":"10.1038\/s41586-020-2599-8","article-title":"A vaccine targeting the RBD of the S protein of SARS-CoV-2 induces protective immunity","volume":"586","author":"Yang","year":"2020","journal-title":"Nature"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1016\/j.cell.2020.06.035","article-title":"A Universal Design of Betacoronavirus Vaccines against COVID-19, MERS, and SARS","volume":"182","author":"Dai","year":"2020","journal-title":"Cell"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1107","DOI":"10.1016\/S1473-3099(21)00127-4","article-title":"Safety and immunogenicity of a recombinant tandem-repeat dimeric RBD-based protein subunit vaccine (ZF2001) against COVID-19 in adults: Two randomised, double-blind, placebo-controlled, phase 1 and 2 trials","volume":"21","author":"Yang","year":"2021","journal-title":"Lancet Infect. Dis."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.virol.2006.04.012","article-title":"Antigenic properties of a transport-competent influenza HA\/HIV Env chimeric protein","volume":"352","author":"Ye","year":"2006","journal-title":"Virology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1128","DOI":"10.5604\/17322693.1077807","article-title":"Subunit vaccines\u2014Antigens, carriers, conjugation methods and the role of adjuvants","volume":"67","author":"Skowicki","year":"2013","journal-title":"Postepy Hig. Med. Dosw."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1038\/s41541-021-00393-6","article-title":"Scientific rationale for developing potent RBD-based vaccines targeting COVID-19","volume":"6","author":"Kleanthous","year":"2021","journal-title":"npj Vaccines"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1346","DOI":"10.1038\/s41467-021-21634-1","article-title":"S-Trimer, a COVID-19 subunit vaccine candidate, induces protective immunity in nonhuman primates","volume":"12","author":"Liang","year":"2021","journal-title":"Nat. Commun."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"20085","DOI":"10.1038\/s41598-020-77077-z","article-title":"Development of CpG-adjuvanted stable prefusion SARS-CoV-2 spike antigen as a subunit vaccine against COVID-19","volume":"10","author":"Kuo","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"e61312","DOI":"10.7554\/eLife.61312","article-title":"Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants","volume":"9","author":"Weisblum","year":"2020","journal-title":"eLife"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1002\/mco2.110","article-title":"SARS-CoV-2 Omicron variant: Characteristics and prevention","volume":"2","author":"He","year":"2021","journal-title":"MedComm"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Graham, F. (Nature Briefing, 2021). Daily briefing: Omicron coronavirus variant puts scientists on alert, Nature Briefing.","DOI":"10.1038\/d41586-021-03564-6"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2002106","DOI":"10.2807\/1560-7917.ES.2020.26.1.2002106","article-title":"Early transmissibility assessment of the N501Y mutant strains of SARS-CoV-2 in the United Kingdom, October to November 2020","volume":"26","author":"Leung","year":"2021","journal-title":"Eurosurveillance"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1038\/s41541-022-00450-8","article-title":"An adjuvanted subunit SARS-CoV-2 spike protein vaccine provides protection against COVID-19 infection and transmission","volume":"7","author":"Tabynov","year":"2022","journal-title":"npj Vaccines"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1038\/s41586-021-03777-9","article-title":"Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization","volume":"596","author":"Planas","year":"2021","journal-title":"Nature"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"701501","DOI":"10.3389\/fimmu.2021.701501","article-title":"SARS-CoV-2 Vaccines Based on the Spike Glycoprotein and Implications of New Viral Variants","volume":"12","author":"Sampieri","year":"2021","journal-title":"Front. Immunol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1016\/S1473-3099(21)00648-4","article-title":"Community transmission and viral load kinetics of the SARS-CoV-2 delta (B.1.617.2) variant in vaccinated and unvaccinated individuals in the UK: A prospective, longitudinal, cohort study","volume":"22","author":"Singanayagam","year":"2022","journal-title":"Lancet Infect. Dis."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"McMillan, C.L.D., Azuar, A., Choo, J.J.Y., Modhiran, N., Amarilla, A.A., Isaacs, A., Honeyman, K.E., Cheung, S.T.M., Liang, B., and Wurm, M.J. (2022). Dermal Delivery of a SARS-CoV-2 Subunit Vaccine Induces Immunogenicity against Variants of Concern. Vaccines, 10.","DOI":"10.3390\/vaccines10040578"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1038\/s41392-020-00352-y","article-title":"A systematic review of SARS-CoV-2 vaccine candidates","volume":"5","author":"Dong","year":"2020","journal-title":"Signal Transduct. Target. Ther."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1016\/j.cell.2021.12.032","article-title":"The Omicron variant is highly resistant against antibody-mediated neutralization: Implications for control of the COVID-19 pandemic","volume":"185","author":"Hoffmann","year":"2022","journal-title":"Cell"}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/23\/22\/13716\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T01:12:33Z","timestamp":1760145153000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/23\/22\/13716"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,8]]},"references-count":25,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2022,11]]}},"alternative-id":["ijms232213716"],"URL":"https:\/\/doi.org\/10.3390\/ijms232213716","relation":{},"ISSN":["1422-0067"],"issn-type":[{"type":"electronic","value":"1422-0067"}],"subject":[],"published":{"date-parts":[[2022,11,8]]}}}