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Published on: September 19, 2016
Cellular immune responses in mice induced by M. tuberculosis PE35-DNA vaccine construct
S N M Hanif1, R Al-Attiyah, A S Mustafa
1Faculty of Medicine, Department of Microbiology, Faculty of Medicine, Kuwait University, Safat, Kuwait. dr.shumaila_nida@yahoo.com
Abstract:
The PE35 (Rv3872) gene of Mycobacterium tuberculosis is present in the region of difference (RD) one that is deleted in all vaccine strains of Mycobacterium bovis bacillus Calmette Guerin. The aim of this study was to clone PE35 DNA into a DNA vaccine plasmid with CMV promoter and interleukin-2 secretory signal and evaluate the recombinant plasmid for induction of antigen-specific cellular responses in mice. DNA corresponding to PE35 was PCR amplified from the genomic DNA of M. tuberculosis H(37) Rv, cloned into pGEMT-Easy vector and sub-cloned into the DNA vaccine vector pUMVC6. BALB/c mice were immunized with recombinant pUMVC6/PE35 and spleen cells were tested for T-helper (Th)1-type (antigen-induced proliferation and secretion of IFN-γ) and Th2-type (IL-5), and anti-inflammatory (IL-10) cytokine responses to pure recombinant PE35 protein and its synthetic peptides. Mice immunized with the recombinant plasmid DNA (pUMVC6/PE35) showed positive Th1-type cellular responses to pure PE35, but not to an irrelevant antigen, i.e. PPE68 (Rv3873). However, the vaccine construct did not induce antigen-specific Th2-type (IL-5) or anti-inflammatory (IL-10) reactivity to PE35. Testing with synthetic peptides showed that Th1-type cells recognizing various epitopes of PE35 were induced in mice immunized with pUMVC6/PE35 DNA. These results suggest that pUMVC6/PE35 may be useful as a safer vaccine candidate against TB.
Insights
This study developed a DNA vaccine using the PE35 gene from Mycobacterium tuberculosis. The vaccine induced a specific cellular immune response in mice, suggesting potential as a safer tuberculosis vaccine candidate.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- The PE35 gene (Rv3872) from Mycobacterium tuberculosis is located in a region deleted in BCG vaccine strains.
- Developing novel vaccine strategies against tuberculosis is crucial.
Purpose of the Study:
- To clone the PE35 gene into a DNA vaccine plasmid.
- To evaluate the recombinant plasmid's ability to induce antigen-specific cellular immune responses in mice.
Main Methods:
- PCR amplification and cloning of PE35 DNA into a pUMVC6 vector.
- Immunization of BALB/c mice with the recombinant pUMVC6/PE35 plasmid.
- Assessment of spleen cell cytokine responses (IFN-γ, IL-5, IL-10) and proliferation.
Main Results:
- Immunization with pUMVC6/PE35 induced Th1-type cellular responses (IFN-γ secretion and proliferation) specific to PE35.
- No significant Th2-type (IL-5) or anti-inflammatory (IL-10) responses were observed.
- Synthetic peptide analysis revealed induction of Th1 cells recognizing various PE35 epitopes.
Conclusions:
- The recombinant DNA vaccine pUMVC6/PE35 effectively elicits antigen-specific Th1 cellular immunity.
- This vaccine construct shows promise as a potentially safer candidate for tuberculosis prevention.
