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Mixed immune response induced in rodents by two naked DNA genes coding for mycobacterial glycosylated proteins
1Unité de Physiopathologie de l'Infection, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
Abstract:
Two genes of Mycobacterium tuberculosis, apa (Rv1860) and pro (Rv1796), coding for two glycosylated excreted proteins have been injected to mice and guinea pigs. They produce an extended immunological response of Th1 and Th2 types. Despite the fact that mycobacterial glycosylation is necessary for a high level of delayed-type hypersensitivity (DTH) reaction, plasmids bearing each of the two genes induced an elevated level of DTH sensitization. An inverse relation between the CpG-N hexamer cluster frequency and the protective effect of injected genes is described. A comparison of the strength of several eukaryotic promoters based on the diameter of the DTH reaction shows that CMVIE followed by the ubiquitin promoter are the most efficient among those tested. A significant protective effect (0.7 log unit CFU) in mice was found for the apa gene while the pro gene had no effect.
Insights
The Mycobacterium tuberculosis apa gene induced a significant protective effect in mice, demonstrating Th1/Th2 immune responses and elevated delayed-type hypersensitivity (DTH) despite glycosylation requirements. The pro gene showed no protective effect.
Area of Science:
- Immunology
- Microbiology
- Genetics
Background:
- Mycobacterium tuberculosis glycosylated excreted proteins play a role in immune responses.
- Understanding the immunogenicity of M. tuberculosis genes is crucial for vaccine development.
Purpose of the Study:
- To investigate the immunological response and protective effects of M. tuberculosis apa and pro genes.
- To compare the efficacy of different eukaryotic promoters in gene delivery for M. tuberculosis antigens.
Main Methods:
- Injection of M. tuberculosis apa and pro genes into mice and guinea pigs.
- Assessment of Th1/Th2 immune responses and delayed-type hypersensitivity (DTH) reactions.
- Evaluation of eukaryotic promoter strength (CMVIE, ubiquitin) and CpG-N hexamer frequency.
Main Results:
- Both apa and pro genes induced Th1/Th2 immune responses and elevated DTH sensitization.
- An inverse relationship was observed between CpG-N hexamer frequency and protective effect.
- CMVIE and ubiquitin promoters were found to be the most efficient.
- The apa gene demonstrated a significant protective effect (0.7 log unit CFU) in mice, while the pro gene did not.
Conclusions:
- The M. tuberculosis apa gene holds potential for vaccine development due to its protective effect and ability to elicit immune responses.
- Eukaryotic promoter choice significantly impacts gene expression and immunogenicity.
- Further research into M. tuberculosis glycosylation and its role in DTH is warranted.