OmpA S.Enteritidis
Description
Functional Roles in Virulence and Pathogenesis
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Intracellular Survival: OmpA stabilizes the Salmonella-containing vacuole (SCV) by upregulating SPI-2 virulence factors (e.g., sifA, ssaV). Deletion of ompA disrupts SCV integrity, exposing bacteria to cytosolic nitrosative stress .
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Membrane Integrity: OmpA-deficient Salmonella exhibit increased outer membrane porosity due to compensatory upregulation of OmpF, enhancing susceptibility to reactive nitrogen intermediates (RNI) .
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Serum Resistance: High OmpA levels correlate with resistance to human serum, likely by reducing complement activation and phagocytosis .
Vaccine Potential
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Subunit Vaccines: Recombinant OmpA induces protective antibodies in poultry, reducing S. Enteritidis transmission via eggs .
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Outer Membrane Vesicles (OMVs): OMVs enriched with OmpA from S. Enteritidis strains (e.g., ΔtolR mutants) show 83.3% protective efficacy in mice. Intramuscular delivery outperforms other routes .
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Immune Response: OMVs elicit Th1/Th2/Th17 responses and antibodies against OmpA and LPS, critical for bacterial clearance .
Table 1: Differential OMP Expression in Serum-Resistant vs. Sensitive S. Enteritidis Strains
| Protein | Role | Serum-Resistant Strains | Serum-Sensitive Strains |
|---|---|---|---|
| OmpA | Structural integrity | High expression | Lower expression |
| PgtE (Protease E) | Serum resistance | Elevated | Absent |
| FliD | Flagellar adhesion | Low | High |
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Mechanistic Insights:
Applications and Implications
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Diagnostics: OmpA serves as a biomarker for Salmonella detection due to its conserved immunogenic epitopes .
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Therapeutic Target: Inhibiting OmpA could destabilize bacterial membranes, enhancing susceptibility to host defenses .
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Agricultural Use: Poultry vaccination with OmpA reduces egg contamination, mitigating foodborne outbreaks .
Product Specs
Product Science Overview
Salmonella Enteritidis is a serovar of Salmonella enterica, a Gram-negative bacterium belonging to the Enterobacteriaceae family. It is a significant pathogen responsible for foodborne illnesses in humans. The outer membrane proteins (OMPs) of Salmonella play crucial roles in its pathogenicity, including adhesion, invasion, and evasion of the host immune system. One such protein is the Outer Membrane Protein-A (OmpA), which has been studied for its potential as a vaccine candidate and its role in immune response modulation.
OmpA is a well-conserved protein found in the outer membrane of Gram-negative bacteria. It consists of an N-terminal β-barrel domain that spans the outer membrane and a C-terminal periplasmic domain. The β-barrel domain forms a pore that allows the passage of small molecules, while the periplasmic domain interacts with peptidoglycan, providing structural stability to the bacterial cell wall.
In Salmonella Enteritidis, OmpA is involved in various functions:
- Adhesion and Invasion: OmpA facilitates the adhesion of Salmonella to host cells and contributes to the invasion process. It interacts with host cell receptors, promoting bacterial entry into the cells.
- Immune Evasion: OmpA helps Salmonella evade the host immune system by inhibiting the complement system, a part of the immune response that targets pathogens for destruction.
- Structural Integrity: OmpA maintains the structural integrity of the bacterial cell wall, which is essential for the survival of the bacterium in hostile environments.
Recombinant OmpA refers to the protein produced through recombinant DNA technology. This involves cloning the gene encoding OmpA into an expression vector, which is then introduced into a host organism, such as Escherichia coli, to produce the protein in large quantities. The recombinant OmpA can be purified and used for various applications, including vaccine development and immunological studies.
- Vaccine Development: Due to its role in immune response modulation, recombinant OmpA is being explored as a potential vaccine candidate. Studies have shown that immunization with recombinant OmpA can induce a protective immune response against Salmonella infections .
- Diagnostic Tools: Recombinant OmpA can be used in the development of diagnostic assays to detect Salmonella infections. The protein can serve as an antigen in serological tests to identify antibodies against Salmonella in patient samples.
- Research: Recombinant OmpA is used in research to study the mechanisms of Salmonella pathogenicity and host-pathogen interactions. It provides insights into how Salmonella adheres to and invades host cells, as well as how it evades the immune system.
