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Intranasal immunization in mice with spore-associated serine-aspartate repeat-containing protein D from Staphylococcus aureus secreted in Bacillus subtilis.

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Title: Intranasal immunization in mice with spore-associated serine-aspartate repeat-containing protein D from Staphylococcus aureus secreted in Bacillus subtilis.
Authors: Vo HTT; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.; Faculty of Natural Sciences, Quy Nhon University, Quy Nhon, Vietnam., Pham VK; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam., Ngo KVT; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam., Nguyen TTN; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam., Nguyen NNY; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam., Nguyen TMD; Faculty of Natural Sciences, Quy Nhon University, Quy Nhon, Vietnam., Nguyen HD; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam. ndhoang@hcmus.edu.vn.; Vietnam National University, Ho Chi Minh City, Vietnam. ndhoang@hcmus.edu.vn.
Source: Biotechnology letters [Biotechnol Lett] 2026 Sep 04; Vol. 48 (5). Date of Electronic Publication: 2026 Sep 04.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Kluwer Academic Publishers Country of Publication: Netherlands NLM ID: 8008051 Publication Model: Electronic Cited Medium: Internet ISSN: 1573-6776 (Electronic) Linking ISSN: 01415492 NLM ISO Abbreviation: Biotechnol Lett Subsets: MEDLINE
Imprint Name(s): Publication: 1999- : Dordrecht : Kluwer Academic Publishers
Original Publication: [Kew, Eng., Science and Technology Letters]
MeSH Terms: Bacillus subtilis*/genetics , Bacillus subtilis*/metabolism , Staphylococcus aureus*/genetics , Staphylococcus aureus*/immunology , Bacterial Proteins*/genetics , Bacterial Proteins*/immunology , Adhesins, Bacterial*/genetics , Adhesins, Bacterial*/immunology , Staphylococcal Vaccines*/immunology , Staphylococcal Vaccines*/administration & dosage , Staphylococcal Vaccines*/genetics, Recombinant Proteins/genetics ; Recombinant Proteins/immunology ; Recombinant Proteins/metabolism ; Spores, Bacterial/genetics ; Spores, Bacterial/immunology ; Antibodies, Bacterial/blood ; Immunoglobulin G/blood ; Immunization/methods ; Animals ; Administration, Intranasal ; Mice ; Mice, Inbred BALB C ; Protein Subunit Vaccines ; Female
Abstract: Staphylococcus aureus is a major human pathogen causing diseases ranging from mild skin infections to life-threatening conditions due to its diverse virulence factors. The emergence of antibiotic-resistant strains underscores the urgent need for an effective vaccine, though none has yet achieved clinical success. The nasal mucosa serves as a natural reservoir in about 30% of individuals and represents a key source of subsequent infections, particularly in immunocompromised patients. Among its virulence factors, SdrD, a surface-anchored MSCRAMM adhesin associated with methicillin-resistant strains (MRSA), promotes adherence to squamous epithelial cells by binding to desmoglein 1, facilitating epithelial attachment, evasion of mucociliary clearance, and subsequent invasion. Bacillus subtilis, an endotoxin-free organism recognized for its safety, has been extensively developed as a platform for secreted recombinant protein production. This study aimed to utilize the host strain B. subtilis to express and secrete recombinant SdrD antigen, using the control of a strong IPTG-inducible Pgrac212 promoter in a pHT expression vector for B. subtilis. Following IPTG induction, extracellular SdrD was analyzed by SDS-PAGE and confirmed by Western blotting using anti-SdrD polyclonal antibodies. The intranasal administration of concentrated secretions, combined with B. subtilis spores as adjuvants, to mice elicited significant antigen-specific IgA and IgG responses, providing both mucosal and systemic immunity. The co-administration with spores enhanced both the magnitude and persistence of antibody responses compared to antigen alone. These findings demonstrate that B. subtilis can serve as an effective platform for recombinant protein secretion and mucosal antigen delivery, supporting its application in vaccine development against S. aureus infection via mucosal route.
(© 2026. The Author(s), under exclusive licence to Springer Nature B.V.)
Competing Interests: Declarations. Conflict of interest: The authors do not have any conflict of interest to declare. Ethical approval: This study was approved by the Animal Care and Use Committee, University of Science (ACUCUS) at Ho Chi Minh City, signed on March 6th, 2024.
References: Ajayi C, Åberg E, Askarian F et al (2018) Genetic variability in the sdrD gene in Staphylococcus aureus from healthy nasal carriers. BMC Microbiol 18:34. https://doi.org/10.1186/s12866-018-1179-7. (PMID: 10.1186/s12866-018-1179-7296611525902956)
Askarian F, Ajayi C, Hanssen A-M et al (2016) The interaction between Staphylococcus aureus SdrD and desmoglein 1 is important for adhesion to host cells. Sci Rep 6:22134. https://doi.org/10.1038/srep22134. (PMID: 10.1038/srep22134269247334770587)
Bagnoli F, Bertholet S, Grandi G (2012) Inferring reasons for the failure of Staphylococcus aureus vaccines in clinical trials. Front Cell Infect Microbiol. https://doi.org/10.3389/fcimb.2012.00016. (PMID: 10.3389/fcimb.2012.00016229196083417391)
Cho H-Y, Yukawa H, Inui M et al (2004) Production of minicellulosomes from Clostridium cellulovorans in Bacillus subtilis WB800. Appl Environ Microbiol 70:5704–5707. https://doi.org/10.1128/AEM.70.9.5704-5707.2004. (PMID: 10.1128/AEM.70.9.5704-5707.200415345466520898)
Dao TT, Truong DD, Duong LN et al (2023) Preparation of Bacillus subtilis cell samples and generation of an SDS-PAGE. BioTechniques 74:123–129. https://doi.org/10.2144/btn-2022-0083. (PMID: 10.2144/btn-2022-008336987985)
Fowler VG, Allen KB, Moreira ED, et al Effect of an Investigational Vaccine for Preventing Staphylococcus aureus Infections After Cardiothoracic Surgery: A Randomized Trial.
González-García S, Bustos-Hamdan A, Hamdan-Partida A, Bustos-Martínez J (2025) Staphylococcus aureus colonization in the pharynx and nasal cavity: why are some people more susceptible? Future Microbiol 0:1–16. https://doi.org/10.1080/17460913.2025.2605944. (PMID: 10.1080/17460913.2025.2605944)
Jeong H, Jeong D-E, Park S-H et al (2018) Complete genome sequence of Bacillus subtilis strain WB800N, an extracellular protease-deficient derivative of strain 168. Microbiol Resour Announc. https://doi.org/10.1128/mra.01380-18. (PMID: 10.1128/mra.01380-18305338786256423)
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Grant Information: 108.06-2019.11 National Foundation for Science and Technology Development
Contributed Indexing: Keywords: Bacillus subtilis; Staphylococcus aureus; Pgrac212; SdrD; Spores
Substance Nomenclature: 0 (Recombinant Proteins)
0 (Bacterial Proteins)
0 (Adhesins, Bacterial)
0 (Antibodies, Bacterial)
0 (Protein Subunit Vaccines)
0 (Immunoglobulin G)
0 (Staphylococcal Vaccines)
Entry Date(s): Date Created: 20260904 Date Completed: 20260904 Latest Revision: 20260904
Update Code: 20260905
DOI: 10.1007/s10529-026-03782-w
PMID: 42696091
Database: MEDLINE
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  Data: Intranasal immunization in mice with spore-associated serine-aspartate repeat-containing protein D from Staphylococcus aureus secreted in Bacillus subtilis.
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  Data: <searchLink fieldCode="AU" term="%22Vo+HTT%22">Vo HTT</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.; Faculty of Natural Sciences, Quy Nhon University, Quy Nhon, Vietnam.<br /><searchLink fieldCode="AU" term="%22Pham+VK%22">Pham VK</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.<br /><searchLink fieldCode="AU" term="%22Ngo+KVT%22">Ngo KVT</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.<br /><searchLink fieldCode="AU" term="%22Nguyen+TTN%22">Nguyen TTN</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.<br /><searchLink fieldCode="AU" term="%22Nguyen+NNY%22">Nguyen NNY</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam.; Vietnam National University, Ho Chi Minh City, Vietnam.<br /><searchLink fieldCode="AU" term="%22Nguyen+TMD%22">Nguyen TMD</searchLink>; Faculty of Natural Sciences, Quy Nhon University, Quy Nhon, Vietnam.<br /><searchLink fieldCode="AU" term="%22Nguyen+HD%22">Nguyen HD</searchLink>; Center for Bioscience and Biotechnology, University of Science, Ho Chi Minh City, Vietnam. ndhoang@hcmus.edu.vn.; Vietnam National University, Ho Chi Minh City, Vietnam. ndhoang@hcmus.edu.vn.
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  Data: <searchLink fieldCode="JN" term="%228008051%22">Biotechnology letters</searchLink> [Biotechnol Lett] 2026 Sep 04; Vol. 48 (5). <i>Date of Electronic Publication: </i>2026 Sep 04.
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  Data: Staphylococcus aureus is a major human pathogen causing diseases ranging from mild skin infections to life-threatening conditions due to its diverse virulence factors. The emergence of antibiotic-resistant strains underscores the urgent need for an effective vaccine, though none has yet achieved clinical success. The nasal mucosa serves as a natural reservoir in about 30% of individuals and represents a key source of subsequent infections, particularly in immunocompromised patients. Among its virulence factors, SdrD, a surface-anchored MSCRAMM adhesin associated with methicillin-resistant strains (MRSA), promotes adherence to squamous epithelial cells by binding to desmoglein 1, facilitating epithelial attachment, evasion of mucociliary clearance, and subsequent invasion. Bacillus subtilis, an endotoxin-free organism recognized for its safety, has been extensively developed as a platform for secreted recombinant protein production. This study aimed to utilize the host strain B. subtilis to express and secrete recombinant SdrD antigen, using the control of a strong IPTG-inducible Pgrac212 promoter in a pHT expression vector for B. subtilis. Following IPTG induction, extracellular SdrD was analyzed by SDS-PAGE and confirmed by Western blotting using anti-SdrD polyclonal antibodies. The intranasal administration of concentrated secretions, combined with B. subtilis spores as adjuvants, to mice elicited significant antigen-specific IgA and IgG responses, providing both mucosal and systemic immunity. The co-administration with spores enhanced both the magnitude and persistence of antibody responses compared to antigen alone. These findings demonstrate that B. subtilis can serve as an effective platform for recombinant protein secretion and mucosal antigen delivery, supporting its application in vaccine development against S. aureus infection via mucosal route.<br /> (© 2026. The Author(s), under exclusive licence to Springer Nature B.V.)
– Name: Abstract
  Label: Competing Interests
  Group: Ab
  Data: Declarations. Conflict of interest: The authors do not have any conflict of interest to declare. Ethical approval: This study was approved by the Animal Care and Use Committee, University of Science (ACUCUS) at Ho Chi Minh City, signed on March 6th, 2024.
– Name: Ref
  Label: References
  Group: RefInfo
  Data: Ajayi C, Åberg E, Askarian F et al (2018) Genetic variability in the sdrD gene in Staphylococcus aureus from healthy nasal carriers. BMC Microbiol 18:34. https://doi.org/10.1186/s12866-018-1179-7. (PMID: <searchLink fieldCode="PM" term="%2210%2E1186%2Fs12866-018-1179-7296611525902956%22">10.1186/s12866-018-1179-7296611525902956)</searchLink><br />Askarian F, Ajayi C, Hanssen A-M et al (2016) The interaction between Staphylococcus aureus SdrD and desmoglein 1 is important for adhesion to host cells. Sci Rep 6:22134. https://doi.org/10.1038/srep22134. (PMID: <searchLink fieldCode="PM" term="%2210%2E1038%2Fsrep22134269247334770587%22">10.1038/srep22134269247334770587)</searchLink><br />Bagnoli F, Bertholet S, Grandi G (2012) Inferring reasons for the failure of Staphylococcus aureus vaccines in clinical trials. Front Cell Infect Microbiol. https://doi.org/10.3389/fcimb.2012.00016. 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  Data: 108.06-2019.11 National Foundation for Science and Technology Development
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  Group:
  Data: <i>Keywords: </i>Bacillus subtilis; Staphylococcus aureus; Pgrac212; SdrD; Spores
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  Label: Substance Nomenclature
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        Value: 10.1007/s10529-026-03782-w
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        Text: English
    Subjects:
      – SubjectFull: Recombinant Proteins genetics
        Type: general
      – SubjectFull: Recombinant Proteins immunology
        Type: general
      – SubjectFull: Recombinant Proteins metabolism
        Type: general
      – SubjectFull: Spores, Bacterial genetics
        Type: general
      – SubjectFull: Spores, Bacterial immunology
        Type: general
      – SubjectFull: Antibodies, Bacterial blood
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      – SubjectFull: Immunoglobulin G blood
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      – SubjectFull: Immunization methods
        Type: general
      – SubjectFull: Animals
        Type: general
      – SubjectFull: Administration, Intranasal
        Type: general
      – SubjectFull: Mice
        Type: general
      – SubjectFull: Mice, Inbred BALB C
        Type: general
      – SubjectFull: Protein Subunit Vaccines
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      – SubjectFull: Female
        Type: general
      – SubjectFull: Bacillus subtilis genetics
        Type: general
      – SubjectFull: Bacillus subtilis metabolism
        Type: general
      – SubjectFull: Staphylococcus aureus genetics
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      – SubjectFull: Staphylococcus aureus immunology
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      – SubjectFull: Staphylococcal Vaccines genetics
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    Titles:
      – TitleFull: Intranasal immunization in mice with spore-associated serine-aspartate repeat-containing protein D from Staphylococcus aureus secreted in Bacillus subtilis.
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            – D: 04
              M: 09
              Text: 2026 Sep 04
              Type: published
              Y: 2026
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            – Type: issn-electronic
              Value: 1573-6776
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