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Protective immune response against methicillin resistant Staphylococcus aureus in a murine model using a DNA vaccine
José P M Senna1, Daniela M Roth, Jaim S Oliveira
1Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Cx Postal 15005, Av Bento Gonçalves, 9500, Porto Alegre RS, CEP 91501-970, Brazil.
Abstract:
Methicillin resistant Staphylococcus aureus (MRSA) are a major pathogen responsible for serious hospital infections worldwide. These bacteria are resistant to all beta-lactam antibiotics due to the production of an additional penicillin binding protein, the PBP2a, encoded by the mecA gene, which shows low affinity for this class of antibiotics. In this study, we cloned an internal region from the transpeptidase domain from the PBP2a into a mammalian expression vector, to be used as DNA vaccine in a Murine model. After three sets of DNA vaccination, the immune response represented by antibodies against a fragment of PBP2a was evaluated by enzyme linked immunosorbent assay (ELISA), showing a significant antibody response. The antibacterial effect of the DNA vaccine was evaluated by intraperitoneal immunization and challenge with a sublethal dose of MRSA for 7 days in mice. After the challenge, the number of bacteria from kidneys from immunized and non-immunized mice were determined. Kidneys from immunized mice had 1000 times less on bacteria than the positive controls (non-immunized mice). The response specificity indicates no effects against the normal PBPs from staphylococci and no effects against Gram positive rods from normal intestinal flora. Our results indicate that the immunization against the PBP2a from MRSA using a DNA vaccine approach could be used as a new strategy to efficiently fight these multiresistant bacteria.
Insights
A novel DNA vaccine targeting penicillin-binding protein 2a (PBP2a) in methicillin-resistant Staphylococcus aureus (MRSA) demonstrated significant antibacterial effects. Immunized mice showed a 1000-fold reduction in MRSA kidney burden, indicating a promising new strategy against these resistant infections.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant global pathogen causing severe hospital-acquired infections.
- Antibiotic resistance in MRSA is primarily due to the mecA gene, which encodes penicillin-binding protein 2a (PBP2a) with low affinity for beta-lactam antibiotics.
Purpose of the Study:
- To develop and evaluate a DNA vaccine targeting PBP2a as a potential strategy against MRSA infections.
- To assess the immunogenicity and efficacy of a DNA vaccine encoding a fragment of PBP2a in a murine model.
Main Methods:
- Cloning of an internal region from the PBP2a transpeptidase domain into a mammalian expression vector.
- DNA vaccination of mice followed by evaluation of antibody response using ELISA.
- Intraperitoneal challenge with MRSA and quantification of bacterial load in kidneys.
Main Results:
- Significant antibody response against PBP2a fragment was observed after vaccination.
- Vaccinated mice exhibited a 1000-fold reduction in kidney bacterial burden compared to non-immunized controls.
- The immune response was specific, showing no adverse effects against normal staphylococcal PBPs or gut flora.
Conclusions:
- DNA vaccination targeting PBP2a is a viable strategy for combating MRSA infections.
- This approach offers a promising new avenue for controlling multiresistant bacterial pathogens.