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Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus MRSA Infection
Published on: September 1, 2023
Cloning, expression and purification of autolysin from methicillin-resistant Staphylococcus aureus: potency and
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:
Staphylococcus aureus (MRSA) is an opportunistic pathogen which causes a variety of clinical diseases and leads to high rates of morbidity and mortality. Development of an effective vaccine appears to be a useful strategy to control the infection. Here, the internal region of atl was cloned into the pET24a plasmid and expressed in E. coli BL21 (DE3). Cloning of atl was confirmed by colony-PCR, enzymatic digestion and sequencing. Protein expressed in E coli, BL21 DE3 and was confirmed with SDS-PAGE and western blot analysis. Subsequently, BALB/c mice were injected subcutaneously three times with 20μg of the recombinant autolysin. After Bleeding, autolysin-specific total IgG antibodies and isotypes were evaluated using ELISA. Opsonophagocytic killing assay was performed and experimental challenge was done by intraperitoneal injection with sub lethal doses of MRSA in mice and also survival rate was regularly monitored. Results showed that vaccinated mice could exhibit higher levels of autolysin-specific antibodies (P<0.0001) with a predominant IgG1 response versus control group. Results from in vitro experiments indicated that S. aureus opsonized with immunized-mice sera displayed significantly increased phagocytic uptake and effective intracellular killing versus non-immunized mice. The number of viable bacteria in the kidney of immunized mice showed 1000 times less than the control mice; additionally, an increased survival rate was found after immunization with the candidate vaccine versus control group. Results from this study demonstrated that the autolysin is a valuable target for the development of immunotherapeutic strategies against S. aureus and candidate vaccines.
Insights
A novel vaccine targeting Staphylococcus aureus autolysin showed promising results. Immunized mice developed protective antibodies, enhanced bacterial clearance, and increased survival rates against MRSA infection.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen causing severe infections.
- Developing effective vaccines is crucial for controlling MRSA infections.
- Autolysin (atl) is explored as a potential vaccine target.
Purpose of the Study:
- To develop and evaluate a recombinant autolysin vaccine against MRSA.
- To assess the immunogenicity and efficacy of the candidate vaccine in a mouse model.
Main Methods:
- Cloning and expression of the internal region of atl in E. coli.
- Confirmation of cloning and protein expression using PCR, digestion, sequencing, SDS-PAGE, and Western blot.
- Immunization of BALB/c mice with recombinant autolysin.
- Evaluation of antibody responses (total IgG, isotypes) via ELISA.
- Assessment of opsonophagocytic killing assay and experimental MRSA challenge.
- Monitoring of bacterial load in kidneys and survival rates.
Main Results:
- Vaccinated mice produced high levels of autolysin-specific IgG antibodies, predominantly IgG1.
- Sera from immunized mice enhanced bacterial phagocytosis and intracellular killing of S. aureus in vitro.
- Significant reduction (1000-fold) in kidney bacterial load observed in immunized mice.
- Increased survival rate in mice vaccinated with the recombinant autolysin.
Conclusions:
- The recombinant autolysin is a viable target for vaccine development against S. aureus.
- The candidate vaccine demonstrates immunoprotective effects against MRSA infection.
- Further development of autolysin-based immunotherapies is warranted.
