Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters

<b>Background/Objectives:</b> Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19), has rapidly evolved, giving rise to multiple Variants of Concern—including Alpha, Beta, Gamma, Delta, and Omicron—which emerged independ...

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Main Authors: Qingmei Jia, Helle Bielefeldt-Ohmann, Saša Masleša-Galić, Richard A. Bowen, Marcus A. Horwitz
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Vaccines
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Online Access:https://www.mdpi.com/2076-393X/13/6/633
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author Qingmei Jia
Helle Bielefeldt-Ohmann
Saša Masleša-Galić
Richard A. Bowen
Marcus A. Horwitz
author_facet Qingmei Jia
Helle Bielefeldt-Ohmann
Saša Masleša-Galić
Richard A. Bowen
Marcus A. Horwitz
author_sort Qingmei Jia
collection DOAJ
description <b>Background/Objectives:</b> Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19), has rapidly evolved, giving rise to multiple Variants of Concern—including Alpha, Beta, Gamma, Delta, and Omicron—which emerged independently across different regions. Licensed COVID-19 vaccines primarily target the highly mutable spike protein, resulting in reduced efficacy due to immune escape by emerging variants. Previously, we developed a live attenuated <i>Francisella tularensis</i> LVS Δ<i>capB</i> single-vector platform COVID-19 vaccine, rLVS Δ<i>capB</i>/MN, expressing the conserved membrane (M) and nucleocapsid (N) proteins from the early SARS-CoV-2 WA-01/2020 strain. In this study, we evaluate the efficacy of rLVS Δ<i>capB</i>/MN and an enhanced version, rLVS Δ<i>capB</i>::RdRp/MN, which additionally expresses the conserved RNA-dependent RNA polymerase (RdRp) protein from the same strain, in a hamster model. <b>Methods:</b> Both vaccine candidates were administered orally or intranasally to golden Syrian hamsters (equal numbers of males and females) and evaluated against intranasal challenge with SARS-CoV-2 Delta (B.1.617.2-AY.1) and Omicron (BA.5) variants. <b>Results:</b> Vaccinated animals developed robust, TH1-biased IgG responses specific to the nucleocapsid protein. Following SARS-CoV-2 challenge, immunized hamsters exhibited reduced weight loss, lower oropharyngeal and lung viral titers, and improved lung pathology scores compared with unvaccinated controls. <b>Conclusion:</b> These findings support the potential of this universal vaccine to provide broad protection against current and future SARS-CoV-2 variants, with minimal need for updating.
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spelling doaj-art-80ad65dbff5a47b09e19de3885c0d6e12025-06-25T14:30:07ZengMDPI AGVaccines2076-393X2025-06-0113663310.3390/vaccines13060633Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in HamstersQingmei Jia0Helle Bielefeldt-Ohmann1Saša Masleša-Galić2Richard A. Bowen3Marcus A. Horwitz4Division of Infectious Diseases, Department of Medicine, 32-150 Center for Health Sciences, School of Medicine, University of California—Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USAAustralian Infectious Diseases Research Centre, University of Queensland, St Lucia, QLD 4072, AustraliaDivision of Infectious Diseases, Department of Medicine, 32-150 Center for Health Sciences, School of Medicine, University of California—Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USADepartment of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USADivision of Infectious Diseases, Department of Medicine, 32-150 Center for Health Sciences, School of Medicine, University of California—Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA<b>Background/Objectives:</b> Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19), has rapidly evolved, giving rise to multiple Variants of Concern—including Alpha, Beta, Gamma, Delta, and Omicron—which emerged independently across different regions. Licensed COVID-19 vaccines primarily target the highly mutable spike protein, resulting in reduced efficacy due to immune escape by emerging variants. Previously, we developed a live attenuated <i>Francisella tularensis</i> LVS Δ<i>capB</i> single-vector platform COVID-19 vaccine, rLVS Δ<i>capB</i>/MN, expressing the conserved membrane (M) and nucleocapsid (N) proteins from the early SARS-CoV-2 WA-01/2020 strain. In this study, we evaluate the efficacy of rLVS Δ<i>capB</i>/MN and an enhanced version, rLVS Δ<i>capB</i>::RdRp/MN, which additionally expresses the conserved RNA-dependent RNA polymerase (RdRp) protein from the same strain, in a hamster model. <b>Methods:</b> Both vaccine candidates were administered orally or intranasally to golden Syrian hamsters (equal numbers of males and females) and evaluated against intranasal challenge with SARS-CoV-2 Delta (B.1.617.2-AY.1) and Omicron (BA.5) variants. <b>Results:</b> Vaccinated animals developed robust, TH1-biased IgG responses specific to the nucleocapsid protein. Following SARS-CoV-2 challenge, immunized hamsters exhibited reduced weight loss, lower oropharyngeal and lung viral titers, and improved lung pathology scores compared with unvaccinated controls. <b>Conclusion:</b> These findings support the potential of this universal vaccine to provide broad protection against current and future SARS-CoV-2 variants, with minimal need for updating.https://www.mdpi.com/2076-393X/13/6/633vaccinesingle-vector platformLVS Δ<i>capB</i> vectorCOVID-19SARS-CoV-2membrane protein
spellingShingle Qingmei Jia
Helle Bielefeldt-Ohmann
Saša Masleša-Galić
Richard A. Bowen
Marcus A. Horwitz
Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
Vaccines
vaccine
single-vector platform
LVS Δ<i>capB</i> vector
COVID-19
SARS-CoV-2
membrane protein
title Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
title_full Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
title_fullStr Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
title_full_unstemmed Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
title_short Universal Bacterium-Vectored COVID-19 Vaccine Expressing Early SARS-CoV-2 Conserved Proteins Cross-Protects Against Late Variants in Hamsters
title_sort universal bacterium vectored covid 19 vaccine expressing early sars cov 2 conserved proteins cross protects against late variants in hamsters
topic vaccine
single-vector platform
LVS Δ<i>capB</i> vector
COVID-19
SARS-CoV-2
membrane protein
url https://www.mdpi.com/2076-393X/13/6/633
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