Evaluation of the immunogenicity and the protective efficacy in mice of a DNA vaccine encoding SP41 from Brucella melitensis
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Published on: September 1, 2023
Ayman Al-Mariri1, Abdul Qader Abbady
1Department of Molecular Biology and Biotechnology, Atomic Energy Commission, PO Box 6091, Damascus, Syria. ascientific1@aec.org.sy
Introduction:
Brucella melitensis is a facultative intracellular Gram-negative bacterial pathogen that may enter the host via ingestion or inhalation, or through conjunctiva or skin abrasions. Some Brucella spp surface proteins (SPs) play an important role in bacterial adhesion and invasion and thus represent targets for the host immune system. Brucella spp surface protein with apparent molecular mass of 41 kDa interacts selectively with HeLa cells.
Methodology:
To evaluate the role of SP41 (41 kDa) as a DNA vaccine against Brucella spp., pCISP41, a plasmid construct for protein expression in mammalian cells, was established. Exogenous SP41 was detected in pCISP41-transfected Vero cell line by immune blotting using specific polyclonal antibody. The protective role of pCISP41 against B. melitensis 16M in mice was evaluated by measuring B and T cell responses in comparison to those achieved with attenuated B. melitensis Rev. 1 vaccine.
Results:
BALB/c mice injected with pCISP41 were able to develop SP41-specific serum immunoglobulin G (IgG) antibodies. In addition, splenocytes from DNA-SP41-vaccinated mice elicited a T-cell-proliferative response and also induced gamma interferon (IFN-γ) production, but not interleukin-5 (IL-5), suggesting the induction of a T-helper-1-dominated immune response. Vaccination with attenuated B. melitensis Rev.1 strain induced better protection levels than DNA vaccination with SP41 against B. melitensis 16M in mice.
Conclusions:
Such responses play an important role against intracellular infecting agents such as Brucella spp. Altogether, our data suggest that SP41 may represent a promising candidate for DNA vaccination against brucellosis, but more investigation to increase its protective efficacy should be done.
Insights
This study explored a DNA vaccine targeting Brucella surface protein 41 (SP41) in mice. While SP41 vaccination induced immune responses, it offered less protection against Brucella melitensis than a traditional vaccine.
Area of Science:
- Immunology
- Microbiology
- Vaccinology
Background:
- Brucella melitensis is a Gram-negative bacterium causing brucellosis.
- Surface proteins (SPs) of Brucella spp. are crucial for host cell adhesion and invasion.
- A 41 kDa Brucella spp. surface protein (SP41) selectively interacts with host cells.
Purpose of the Study:
- To assess the efficacy of a DNA vaccine encoding SP41 (pCISP41) against Brucella spp. infection in a mouse model.
- To evaluate the immune responses, including B and T cell activity, generated by the SP41 DNA vaccine.
- To compare the protective potential of the SP41 DNA vaccine with an established attenuated Brucella vaccine.
Main Methods:
- Construction of a plasmid (pCISP41) for expressing SP41 in mammalian cells.
- Detection of exogenous SP41 in transfected cells using immune blotting.
- Assessment of humoral (serum IgG) and cellular (splenocyte proliferation, cytokine production) immune responses in mice vaccinated with pCISP41.
- Evaluation of protection against Brucella melitensis 16M challenge in mice.
Main Results:
- Mice vaccinated with pCISP41 developed SP41-specific serum IgG antibodies.
- Splenocytes from vaccinated mice showed T-cell proliferation and gamma interferon (IFN-γ) production, indicating a T-helper-1 immune response.
- The attenuated Brucella melitensis Rev.1 vaccine provided a higher level of protection compared to the SP41 DNA vaccine.
Conclusions:
- SP41 elicits specific immune responses, including T-helper-1 biased immunity, in mice.
- SP41 shows potential as a candidate for DNA vaccination against brucellosis.
- Further research is needed to enhance the protective efficacy of SP41-based DNA vaccines.
