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Improving the Immunogenicity of the Mycobacterium bovis BCG Vaccine by Non-Genetic Bacterial Surface Decoration Using the Avidin-Biotin System.

Liao TY, Lau A, Joseph S, Hytönen V, Hmama Z - PLoS ONE (2015)

Bottom Line: Modifications of BCG surface did not affect its growth in culture media neither its survival within the host cell.We also found that BCG decorated with Mtb specific antigen ESAT6 successfully induces the expansion of specific T cell responses.This novel technology, therefore, represents a practical and effective alternative to DNA-based gene expression for upgrading the current BCG vaccine.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine and Vancouver Costal Health Research Institute, University of British Columbia, Vancouver, BC, Canada.

ABSTRACT
Current strategies to improve the current BCG vaccine attempt to over-express genes encoding specific M. tuberculosis (Mtb) antigens and/or regulators of antigen presentation function, which indeed have the potential to reshape BCG in many ways. However, these approaches often face serious difficulties, in particular the efficiency and stability of gene expression via nucleic acid complementation and safety concerns associated with the introduction of exogenous DNA. As an alternative, we developed a novel non-genetic approach for rapid and efficient display of exogenous proteins on bacterial cell surface. The technology involves expression of proteins of interest in fusion with a mutant version of monomeric avidin that has the feature of reversible binding to biotin. Fusion proteins are then used to decorate the surface of biotinylated BCG. Surface coating of BCG with recombinant proteins was highly reproducible and stable. It also resisted to the freeze-drying shock routinely used in manufacturing conventional BCG. Modifications of BCG surface did not affect its growth in culture media neither its survival within the host cell. Macrophages phagocytized coated BCG bacteria, which efficiently delivered their surface cargo of avidin fusion proteins to MHC class I and class II antigen presentation compartments. Thereafter, chimeric proteins corresponding to a surrogate antigen derived from ovalbumin and the Mtb specific ESAT6 antigen were generated and tested for immunogenicity in vaccinated mice. We found that BCG displaying ovalbumin antigen induces an immune response with a magnitude similar to that induced by BCG genetically expressing the same surrogate antigen. We also found that BCG decorated with Mtb specific antigen ESAT6 successfully induces the expansion of specific T cell responses. This novel technology, therefore, represents a practical and effective alternative to DNA-based gene expression for upgrading the current BCG vaccine.

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Related in: MedlinePlus

Schematic summary of BCG surface decoration approach.BCG is first surface biotinylated with hydrosoluble biotin then exposed to mAvidin chimeric proteins for reversible surface decoration with antigens. Modified BCG is then inoculated into animals where it is expected to deliver antigens to induce specific T cell responses. Mouse picture was taken by one of the contributor to this work.
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pone.0145833.g010: Schematic summary of BCG surface decoration approach.BCG is first surface biotinylated with hydrosoluble biotin then exposed to mAvidin chimeric proteins for reversible surface decoration with antigens. Modified BCG is then inoculated into animals where it is expected to deliver antigens to induce specific T cell responses. Mouse picture was taken by one of the contributor to this work.

Mentions: In conclusion, our study provides strong data to support proof-of-concept for a novel strategy aimed at optimizing BCG for vaccinal purposes (Fig 10). It is based on rapid, reproducible and reversible surface decoration with one or multiple proteins of interest via binding of avidin chimeric proteins to biotinylated bacteria capable of delivering their cargo inside antigen presenting cells in vivo. Overall, this study revealed the enormous potential of the avidin-biotin system in TB vaccine development and hopefully would also give new insights for other successful therapeutic applications.


Improving the Immunogenicity of the Mycobacterium bovis BCG Vaccine by Non-Genetic Bacterial Surface Decoration Using the Avidin-Biotin System.

Liao TY, Lau A, Joseph S, Hytönen V, Hmama Z - PLoS ONE (2015)

Schematic summary of BCG surface decoration approach.BCG is first surface biotinylated with hydrosoluble biotin then exposed to mAvidin chimeric proteins for reversible surface decoration with antigens. Modified BCG is then inoculated into animals where it is expected to deliver antigens to induce specific T cell responses. Mouse picture was taken by one of the contributor to this work.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696857&req=5

pone.0145833.g010: Schematic summary of BCG surface decoration approach.BCG is first surface biotinylated with hydrosoluble biotin then exposed to mAvidin chimeric proteins for reversible surface decoration with antigens. Modified BCG is then inoculated into animals where it is expected to deliver antigens to induce specific T cell responses. Mouse picture was taken by one of the contributor to this work.
Mentions: In conclusion, our study provides strong data to support proof-of-concept for a novel strategy aimed at optimizing BCG for vaccinal purposes (Fig 10). It is based on rapid, reproducible and reversible surface decoration with one or multiple proteins of interest via binding of avidin chimeric proteins to biotinylated bacteria capable of delivering their cargo inside antigen presenting cells in vivo. Overall, this study revealed the enormous potential of the avidin-biotin system in TB vaccine development and hopefully would also give new insights for other successful therapeutic applications.

Bottom Line: Modifications of BCG surface did not affect its growth in culture media neither its survival within the host cell.We also found that BCG decorated with Mtb specific antigen ESAT6 successfully induces the expansion of specific T cell responses.This novel technology, therefore, represents a practical and effective alternative to DNA-based gene expression for upgrading the current BCG vaccine.

View Article: PubMed Central - PubMed

Affiliation: Division of Infectious Diseases, Department of Medicine and Vancouver Costal Health Research Institute, University of British Columbia, Vancouver, BC, Canada.

ABSTRACT
Current strategies to improve the current BCG vaccine attempt to over-express genes encoding specific M. tuberculosis (Mtb) antigens and/or regulators of antigen presentation function, which indeed have the potential to reshape BCG in many ways. However, these approaches often face serious difficulties, in particular the efficiency and stability of gene expression via nucleic acid complementation and safety concerns associated with the introduction of exogenous DNA. As an alternative, we developed a novel non-genetic approach for rapid and efficient display of exogenous proteins on bacterial cell surface. The technology involves expression of proteins of interest in fusion with a mutant version of monomeric avidin that has the feature of reversible binding to biotin. Fusion proteins are then used to decorate the surface of biotinylated BCG. Surface coating of BCG with recombinant proteins was highly reproducible and stable. It also resisted to the freeze-drying shock routinely used in manufacturing conventional BCG. Modifications of BCG surface did not affect its growth in culture media neither its survival within the host cell. Macrophages phagocytized coated BCG bacteria, which efficiently delivered their surface cargo of avidin fusion proteins to MHC class I and class II antigen presentation compartments. Thereafter, chimeric proteins corresponding to a surrogate antigen derived from ovalbumin and the Mtb specific ESAT6 antigen were generated and tested for immunogenicity in vaccinated mice. We found that BCG displaying ovalbumin antigen induces an immune response with a magnitude similar to that induced by BCG genetically expressing the same surrogate antigen. We also found that BCG decorated with Mtb specific antigen ESAT6 successfully induces the expansion of specific T cell responses. This novel technology, therefore, represents a practical and effective alternative to DNA-based gene expression for upgrading the current BCG vaccine.

Show MeSH
Related in: MedlinePlus