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Updated: Feb 23, 2026
Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus MRSA Infection
Published on: September 1, 2023
A novel recombinant vaccine candidate comprising PBP2a and autolysin against Methicillin Resistant Staphylococcus
Setareh Haghighat1, Seyed Davar Siadat2, Seyed Mehdi Rezayat Sorkhabadi3
1Department of Microbiology, Faculty of Advanced Sciences and Technology, Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS), Tehran, Iran.
Abstract:
The methicillin-resistant Staphylococcus aureus infection is a hot topic area in microbiology research. Here a novel vaccine candidate consisting of recombinant PBP2a and autolysin proteins were used. The proteins over expressed in E.coli BL21 (DE3) cells, and purified by the Ni-NTA affinity column and conjugated using EDAC and ADH as a linker and spacer, respectively. To investigate the immunogenicity and protective effects of recombinant proteins, 5 and 20μg of proteins in various formulations were subcutaneously injected in different groups. Two booster vaccinations were carried out in three-week intervals and blood samples were collected three weeks after each injection. To evaluate the immune response, total IgG, IgG1, IgG2a, and IgG2b were analyzed. Immunization of mice with r-autolysin and r-autolysin-PBP2a mixture raised total IgGantibody. Additionally, both IgG1 and IgG2a responses induced. Opsonophagocytosis assay showed that anti r-PBP2a and r-autolysin IgG not only promoted phagocytosis of S.aureus, but also decreased the number of viable bacterial cells. Furthermore, survival rate of experimental mice increased in the bacteremia infection. Our results demonstrated that active vaccination with a mixture of r-PBP2a/r-autolysin and conjugate form vaccine reduced the mortality rate and protected mice against lethal MRSA challenge as well as single proteins.
Insights
This study developed a novel vaccine using recombinant proteins to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. The vaccine demonstrated significant protection in mice, reducing mortality against lethal MRSA challenges.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat due to its resistance to antibiotics.
- Developing effective vaccines against MRSA is crucial for public health.
- Novel vaccine candidates targeting key MRSA proteins are under investigation.
Purpose of the Study:
- To evaluate the immunogenicity and protective efficacy of a novel vaccine candidate composed of recombinant PBP2a and autolysin proteins against MRSA.
- To assess the immune response, including antibody production and phagocytic activity, induced by the vaccine.
- To determine the survival rate of mice challenged with MRSA after vaccination.
Main Methods:
- Recombinant PBP2a and autolysin proteins were expressed in E. coli, purified, and conjugated.
- Mice were immunized with varying doses of the vaccine formulations, followed by booster shots.
- Immune responses were analyzed by measuring total IgG, IgG1, IgG2a, and IgG2b levels.
- Opsonophagocytosis assays and bacteremia infection models were used to assess protective effects.
Main Results:
- Immunization with the recombinant proteins induced a robust IgG antibody response, including IgG1 and IgG2a subclasses.
- The generated antibodies promoted phagocytosis of S. aureus and reduced viable bacterial counts.
- Vaccination significantly increased the survival rate of mice challenged with MRSA.
- The combined r-PBP2a/r-autolysin vaccine, particularly in conjugate form, offered enhanced protection compared to single proteins.
Conclusions:
- The novel vaccine candidate comprising r-PBP2a and r-autolysin demonstrates promising immunogenicity and protective capabilities against MRSA.
- Active vaccination with this recombinant protein-based vaccine can effectively reduce mortality and protect against lethal MRSA infections.
- This study provides a strong foundation for the development of a potential MRSA vaccine.
