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Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
Published on: June 25, 2015
The two-component system sivS/R regulates virulence in Streptococcus iniae.
Shelly Bolotin1, Jeffrey D Fuller, Darrin J Bast
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
The SivS/R system in Streptococcus iniae controls virulence and gene expression. Deleting SivS/R reduces bacterial virulence and affects surface protein levels, impacting disease potential.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Streptococcus iniae is a significant fish pathogen causing mortality.
- It can also cause human soft-tissue infections.
- The sivS/R two-component system regulates S. iniae capsule expression.
Purpose of the Study:
- To investigate the role of the sivS/R system in S. iniae virulence.
- To identify genes regulated by sivS/R.
- To determine the effect of sivS/R on surface protein expression.
Main Methods:
- Construction and testing of a sivS/R deletion-insertion mutant (9117Deltasiv) in a murine bacteremia model.
- Real-time PCR to quantify gene expression (sagA, cfi).
- SDS-PAGE and Mass Spectrometry (MS) to analyze surface proteins.
Main Results:
- The 9117Deltasiv mutant exhibited transient bacteremia and reduced virulence in mice.
- SivS/R regulates the expression of streptolysin S (sagA) and CAMP factor (cfi) genes.
- The mutant showed downregulation of a putative lipoprotein, hyaluronate-associated protein, and pyruvate kinase.
Conclusions:
- SivS/R is a key regulator of S. iniae virulence in vivo.
- The system controls the expression of multiple virulence-associated genes and surface proteins.
- Understanding SivS/R function offers targets for controlling S. iniae infections.
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