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Immunogenicity and efficacy of a tuberculosis DNA vaccine encoding the components of the secreted antigen 85 complex
1Pasteur Institute of Brussels, Mycobacterial Immunology, Department Virology, Brussels, Belgium.
Abstract:
BALB/c and C57BL/6 mice were injected intramuscularly with plasmid DNA encoding the three components of the immunodominant 30-32 kDa antigen 85 complex (Ag85A, Ag85B, and Ag85C) from Mycobacterium tuberculosis culture filtrate, in order to investigate the utility of nucleic acid vaccination for induction of immune responses against mycobacterial antigens. Ag85A and Ag85B encoding plasmids induced a robust Th1-like response towards native Ag85, characterized by elevated levels of interleukin (IL)-2, interferon-gamma, and TNF-alpha. Levels of IL-4, IL-6, and IL-10 were low or undetectable. Plasmid encoding Ag85C was not effective. Cytotoxic T cell activity was also generated in in vitro restimulated splenocyte cultures from Ag85A and Ag85B DNA vaccinated mice. Finally, Ag85A and Ag85B DNA vaccination conferred significant protection against mycobacterial replication in lungs from B6 mice, subsequently challenged. Therefore, this technique may be useful for the definition of protective antigens of M. tuberculosis and the development of a more effective tuberculosis vaccine.
Insights
DNA vaccination using antigen 85A and 85B genes from Mycobacterium tuberculosis induced a protective Th1 immune response and reduced bacterial replication. This approach shows promise for developing a new tuberculosis vaccine.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Tuberculosis (TB) remains a global health challenge, necessitating novel vaccine strategies.
- The antigen 85 complex (Ag85) is a key target for immune responses against Mycobacterium tuberculosis.
- Nucleic acid vaccination offers a potential platform for delivering mycobacterial antigens.
Purpose of the Study:
- To evaluate the efficacy of DNA vaccination encoding components of the Mycobacterium tuberculosis antigen 85 complex (Ag85A, Ag85B, Ag85C).
- To assess the induction of cell-mediated immune responses and protection against M. tuberculosis challenge.
- To explore the potential of DNA vaccination for tuberculosis vaccine development.
Main Methods:
- BALB/c and C57BL/6 mice were intramuscularly immunized with plasmid DNA encoding Ag85A, Ag85B, or Ag85C.
- Immune responses were assessed by measuring cytokine levels (IL-2, IFN-gamma, TNF-alpha, IL-4, IL-6, IL-10) and cytotoxic T cell activity.
- Mice were challenged with M. tuberculosis, and mycobacterial replication in the lungs was quantified.
Main Results:
- DNA vaccines encoding Ag85A and Ag85B induced a strong Th1-like immune response, characterized by elevated levels of IL-2, interferon-gamma, and TNF-alpha.
- Ag85C DNA vaccine was ineffective in eliciting a significant immune response.
- Ag85A and Ag85B DNA vaccination generated cytotoxic T cell activity and conferred significant protection against M. tuberculosis replication in the lungs of challenged mice.
Conclusions:
- DNA vaccination with Ag85A and Ag85B genes is a viable strategy for inducing protective immunity against Mycobacterium tuberculosis.
- This approach facilitates the identification of protective antigens and holds promise for the development of an effective tuberculosis vaccine.
- Further research into nucleic acid vaccination targeting key mycobacterial antigens is warranted.