Master of Science
Nhi NY Nguyen
Center for Bioscience and Biotechnology, VNUHCM-University of Science, Ho Chi Minh City, Vietnam
Title: Bacillus subtilis spore display of Staphylococcus aureus antigens as an oral vaccine platform
Nhi NY Nguyen1,2, Trang TP Phan 1,2, Hoang Duc Nguyen1,2*
1 Center for Bioscience and Biotechnology, VNUHCM-University of Science, Ho Chi Minh City, Vietnam
2 Vietnam National University Ho Chi Minh City, Vietnam
Bacillus subtilis spores are strong candidates for use as oral vaccine vectors. They are safe, highly stable under harsh conditions, able to display foreign proteins on their surface, naturally adjuvant-active, and easy to genetically modify. These characteristics allow spores to protect antigens during passage through the acidic stomach environment and deliver them efficiently to the gut immune system. In this study, B. subtilis was engineered to express Staphylococcus aureus antigens using surface display technology. Target antigens were fused to the spore coat anchor protein CotB for surface presentation. Expression vectors were transferred into B. subtilis and integrated into the chromosome via homologous recombination. Surface display of the fusion proteins was confirmed by Western blot, spore ELISA, and fluorescence microscopy. Swiss mice were orally immunized with three doses of recombinant spores to evaluate in vivo antigen delivery and immunogenicity. ELISA analysis of serum IgG and fecal IgA showed significant increases, demonstrating successful antigen transit through the gastrointestinal tract and induction of both systemic and mucosal antibody responses. This work establishes a B. subtilis based platform capable of displaying multiple S. aureus antigens, including both toxin-associated and surface- associated proteins. The study also identifies biological effects linked to antigen expression, such as enhanced sporulation efficiency and increased stress resistance in strains expressing MntC. Overall, these findings provide experimental evidence supporting B. subtilis spores as a stable, low cost, and scalable vaccine vector, and highlight their potential for developing oral vaccines against S. aureus within a One Health framework.
Biography of the presenting author
Nhi N.Y. Nguyen is a PhD student in Microbiology at the University of Science, Vietnam National University Ho Chi Minh City. She graduated with a Bachelor of Science in Biotechnology (Medical major) in 2018 and started her PhD in 2019. From 2020 to 2021, she trained at the University of California, San Francisco, USA, where she worked on Staphylococcus aureus and animal infection models. Since 2018, she has been a researcher at the Center for Bioscience and Biotechnology, University of Science Ho Chi Minh City. In 2025, she received further training in immunology techniques (ELISpot, flow cytometry, and intracellular cytokine staining) at the Dunachie Group, Peter Medawar Building for Pathogen Research, University of Oxford, UK.
Her current project focuses on engineering Bacillus subtilis to explore its potential as an mucosal vaccine vector. Her research interests include microbiology, pathogen biology, and immunology.
Presenting author details
Full name: Nhi NY Nguyen Contact number: +84855120946
Email: ngocnhi.jenny0308@gmail.com
Session name/ number: Category: Oral presentation