{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T18:07:46Z","timestamp":1785434866125,"version":"3.56.0"},"reference-count":42,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,12,18]],"date-time":"2023-12-18T00:00:00Z","timestamp":1702857600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NIH","award":["# 1-R21 DK063576-01"],"award-info":[{"award-number":["# 1-R21 DK063576-01"]}]},{"name":"NIH","award":["2019\u20132022"],"award-info":[{"award-number":["2019\u20132022"]}]},{"name":"NIH","award":["RRF-2.3.1-21"],"award-info":[{"award-number":["RRF-2.3.1-21"]}]},{"name":"NIH","award":["RRF-2.3.1-21-2022-00001"],"award-info":[{"award-number":["RRF-2.3.1-21-2022-00001"]}]},{"name":"John Backer Philanthropic Fund","award":["# 1-R21 DK063576-01"],"award-info":[{"award-number":["# 1-R21 DK063576-01"]}]},{"name":"John Backer Philanthropic Fund","award":["2019\u20132022"],"award-info":[{"award-number":["2019\u20132022"]}]},{"name":"John Backer Philanthropic Fund","award":["RRF-2.3.1-21"],"award-info":[{"award-number":["RRF-2.3.1-21"]}]},{"name":"John Backer Philanthropic Fund","award":["RRF-2.3.1-21-2022-00001"],"award-info":[{"award-number":["RRF-2.3.1-21-2022-00001"]}]},{"name":"National Recovery Fund","award":["# 1-R21 DK063576-01"],"award-info":[{"award-number":["# 1-R21 DK063576-01"]}]},{"name":"National Recovery Fund","award":["2019\u20132022"],"award-info":[{"award-number":["2019\u20132022"]}]},{"name":"National Recovery Fund","award":["RRF-2.3.1-21"],"award-info":[{"award-number":["RRF-2.3.1-21"]}]},{"name":"National Recovery Fund","award":["RRF-2.3.1-21-2022-00001"],"award-info":[{"award-number":["RRF-2.3.1-21-2022-00001"]}]},{"name":"Recovery and Resilience Facility (RRF)","award":["# 1-R21 DK063576-01"],"award-info":[{"award-number":["# 1-R21 DK063576-01"]}]},{"name":"Recovery and Resilience Facility (RRF)","award":["2019\u20132022"],"award-info":[{"award-number":["2019\u20132022"]}]},{"name":"Recovery and Resilience Facility (RRF)","award":["RRF-2.3.1-21"],"award-info":[{"award-number":["RRF-2.3.1-21"]}]},{"name":"Recovery and Resilience Facility (RRF)","award":["RRF-2.3.1-21-2022-00001"],"award-info":[{"award-number":["RRF-2.3.1-21-2022-00001"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Mucosal vaccines protect against respiratory virus infection by stimulating the production of IgA antibodies that protect against virus invasion of the mucosal epithelium. In this study, a novel protein subunit mucosal vaccine was constructed for protection against infection by the beta coronavirus SARS-CoV-2. The vaccine was assembled by linking a gene encoding the SARS-CoV-2 virus S1 angiotensin converting enzyme receptor binding domain (ACE-2-RBD) downstream from a DNA fragment encoding the cholera toxin B subunit (CTB), a mucosal adjuvant known to stimulate vaccine immunogenicity. A 42 kDa vaccine fusion protein was identified in homogenates of transformed E. coli BL-21 cells by acrylamide gel electrophoresis and by immunoblotting against anti-CTB and anti-ACE-2-RBD primary antibodies. The chimeric CTB-SARS-CoV-2-ACE-2-RBD vaccine fusion protein was partially purified from clarified bacterial homogenates by nickel affinity column chromatography. Further vaccine purification was accomplished by polyacrylamide gel electrophoresis and electro-elution of the 42 kDa chimeric vaccine protein. Vaccine protection against SARS-CoV-2 infection was assessed by oral, nasal, and parenteral immunization of BALB\/c mice with the CTB-SARS-CoV-2-ACE-2-RBD protein. Vaccine-induced SARS-CoV-2 specific antibodies were quantified in immunized mouse serum by ELISA analysis. Serum from immunized mice contained IgG and IgA antibodies that neutralized SARS-CoV-2 infection in Vero E6 cell cultures. In contrast to unimmunized mice, cytological examination of cell necrosis in lung tissues excised from immunized mice revealed no detectable cellular abnormalities. Mouse behavior following vaccine immunization remained normal throughout the duration of the experiments. Together, our data show that a CTB-adjuvant-stimulated CTB-SARS-CoV-2-ACE-2-RBD chimeric mucosal vaccine protein synthesized in bacteria can produce durable and persistent IgA antibodies in mice that neutralize the SARS-CoV-2 subvariant Omicron BA.1.1.<\/jats:p>","DOI":"10.3390\/vaccines11121865","type":"journal-article","created":{"date-parts":[[2023,12,18]],"date-time":"2023-12-18T08:55:29Z","timestamp":1702889729000},"page":"1865","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["A CTB-SARS-CoV-2-ACE-2 RBD Mucosal Vaccine Protects Against Coronavirus Infection"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9889-529X","authenticated-orcid":false,"given":"B\u00e9la","family":"D\u00e9nes","sequence":"first","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"},{"name":"Department of Microbiology and Infectious Diseases, University of Veterinary Medicine Budapest, 1143 Budapest, Hungary"},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryan","family":"Fuller","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wayne","family":"Kelin","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-7293-6813","authenticated-orcid":false,"given":"Tessa","family":"Levin","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jaipuneet","family":"Gil","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aaren","family":"Harewood","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"},{"name":"Department of Basic Sciences, Oakwood University, Huntsville, AL 35896, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M\u00e1rta","family":"L\u0151rincz","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Infectious Diseases, University of Veterinary Medicine Budapest, 1143 Budapest, Hungary"},{"name":"National Laboratory of Infectious Animal Diseases, Antimicrobial Resistance, Veterinary Public Health and Food Chain Safety, University of Veterinary Medicine Budapest, 1078 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3235-4386","authenticated-orcid":false,"given":"Nathan","family":"Wall","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"},{"name":"Division of Biochemistry, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6649-2798","authenticated-orcid":false,"given":"Anthony","family":"Firek","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"},{"name":"Comparative Effectiveness and Clinical Outcomes Research Center (CECORC), Riverside University Health System Medical Center, Moreno Valley, CA 92555, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William","family":"Langridge","sequence":"additional","affiliation":[{"name":"Center for Health Disparities and Molecular Medicine, Loma Linda University School of Medicine, Mortensen Hall, Loma Linda, CA 92350, USA"},{"name":"Division of Biochemistry, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, 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