Project description:The purpose of this study was to identify Group B Streptococcus (GBS) genes that are controlled by the CiaR response regulator. Deletion of the GBS ciaR gene resulted in a significant decrease in intracellular survival within neutrophils, murine macrophages, and human BMEC, which was linked to increased susceptibility to killing by antimicrobial peptides, lysozyme, and reactive oxygen species. Furthermore, competition experiments in mice showed that wild-type GBS had a significant survival advantage compared to the isogenic ciaR mutant. Microarray analysis comparing gene expression between the wild-type and ciaR mutant strains revealed several CiaR-regulated genes that may contribute to GBS stress tolerance and subversion of host defenses.
Project description:The purpose of this study was to identify Group B Streptococcus (GBS) genes that are controlled by the CiaR response regulator. Deletion of the GBS ciaR gene resulted in a significant decrease in intracellular survival within neutrophils, murine macrophages, and human BMEC, which was linked to increased susceptibility to killing by antimicrobial peptides, lysozyme, and reactive oxygen species. Furthermore, competition experiments in mice showed that wild-type GBS had a significant survival advantage compared to the isogenic ciaR mutant. Microarray analysis comparing gene expression between the wild-type and ciaR mutant strains revealed several CiaR-regulated genes that may contribute to GBS stress tolerance and subversion of host defenses. Two cultures each of the wild-type GBS strain (COH1) and the isogenic ciaR mutant were grown in Todd-Hewitt broth to an optical density of 0.3. Cells were disrupted by shaking with glass beads and RNA was isolated by a Trizol method. A custom Affymetrix chip with a design based on the COH1 genomic sequence was used to analyze gene expression.
Project description:Streptococcus agalactiae (Lancefield’s group B Streptococcus, GBS) is a major bacterial species of genus Streptococcus and has medical and veterinary importance by affecting mainly humans (Maione et al., 2005; Johri et al., 2006), cattle (Keefe, 1997) and fish (Mian et al., 2009). The GBS is the most important pathogen for the Nile tilapia, a global commodity of the aquaculture sector, causing outbreaks of septicemia and meningoencephalitis (Hernández et al., 2009; Mian et al., 2009).
Project description:The CiaRH and LiaFSR two-component regulatory systems in Streptococcus agalactiae (Group B Streptococcus, GBS) are essential mediators of the organism s response to biologically important sources of environmental stress, and positive regulators of GBS virulence. Transcriptional profiling of CiaR mutant GBS and LiaR mutant GBS reveals that LiaR is positively-regulated by CiaR, and the individual mutant transcriptomes share a number of commonly-regulated genes. To determine the GBS response to loss of both of these key regulatory systems, we constructed a GBS mutant strain with non-polar deletions in both ciaR and liaR, and performed transcriptional profiling using DNA microarray analysis, comparing wild-type GBS to CiaR/LiaR double mutant GBS under non-stressed conditions.
Project description:Streptococcus agalactiae (Lancefield’s group B Streptococcus, GBS) is a major bacterial species of genus Streptococcus and has medical and veterinary importance by affecting mainly humans (Maione et al., 2005; Johri et al., 2006), cattle (Keefe, 1997) and fish (Mian et al., 2009). The GBS is the most important pathogen for the Nile tilapia, a global commodity of the aquaculture sector, causing outbreaks of septicemia and meningoencephalitis (Hernández et al., 2009; Mian et al., 2009). This study aimed to evaluate the global abundancy of proteins among the main genotypes of GBS isolated from fish identified in Brazil using a label free shotgun liquid chromatography-ultra definition mass spectrometry (LC-UDMSE) approach and to compare the differential expression of proteins identified between isolates from fish and human.