Project description:Regulation of gene expression in response to variable and often adverse environmental conditions is an essential component of microbial pathogenesis. We identified the two-component regulatory system CiaRH in a screen for genes essential for the survival of Streptococcus agalactiae (Group B Streptococcus, GBS) on exposure to in vitro models of environmental stress. We constructed site-directed, non-polar deletion mutations in the regulator gene ciaR and compared the growth of CiaR mutant GBS to wild-type GBS under stressed conditions. CiaR mutant GBS are more sensitive than wild-type GBS to elevated temperature, low pH, chemical mutagens and ultraviolet light; the mutants are also more sensitive to cell-wall active antibiotics and antimicrobial peptides. CiaR mutant strains are markedly attenuated in a mouse model of GBS sepsis. To determine the genes regulated by CiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to CiaR mutant GBS under non-stressed conditions.
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of early-onset neonatal bacterial infection. Evasion of innate immune defenses is critical to neonatal GBS disease pathogenesis. Effectors of the innate immune system such as antimicrobial peptides, as well as numerous antibiotics, target the peptidoglycan layer of the gram positive bacterial cell wall. The intramembrane-sensing histidine kinase class of two-component regulatory systems has recently been identified as important to the gram-positive response to cell wall stress. We identified and characterized the GBS homolog of LiaR, the response regulator component of the LiaFSR system and constructed site-directed, non-polar deletion mutations in the regulator gene liaR. GBS LiaR deletion mutant strains are more susceptible to cell wall active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (colistin, nisin and the human cathelicidin LL-37) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and GBS pneumonia. To determine the genes regulated by LiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to LiaR mutant GBS under non-stressed conditions.
Project description:Streptococcus agalactiae (Group B Streptococcus, GBS) is a leading cause of early-onset neonatal bacterial infection. Evasion of innate immune defenses is critical to neonatal GBS disease pathogenesis. Effectors of the innate immune system such as antimicrobial peptides, as well as numerous antibiotics, target the peptidoglycan layer of the gram positive bacterial cell wall. The intramembrane-sensing histidine kinase class of two-component regulatory systems has recently been identified as important to the gram-positive response to cell wall stress. We identified and characterized the GBS homolog of LiaR, the response regulator component of the LiaFSR system and constructed site-directed, non-polar deletion mutations in the regulator gene liaR. GBS LiaR deletion mutant strains are more susceptible to cell wall active antibiotics (vancomycin and bacitracin) as well as antimicrobial peptides (colistin, nisin and the human cathelicidin LL-37) compared to isogenic wild-type GBS. LiaR mutant GBS are significantly attenuated in mouse models of both GBS sepsis and GBS pneumonia. To determine the genes regulated by LiaR that account for these defects, transcriptional profiling was performed using DNA microarray analysis, comparing wild-type GBS to LiaR mutant GBS under non-stressed conditions. Two separate RNA samples were extracted for each condition. One flip-dye replicate (2 hybridizations) was obtained for each pair of RNA samples for 4 hybridizations total.
Project description:Total RNA was isolated from mid-log phase Streptococcus agalactiae 874391 wild-type cells grown in Todd-Hewitt broth (THB) medium and sequenced using Illumina NextSeq500
Project description:Total RNA was isolated from mid-log phase Streptococcus agalactiae 874391 wild-type cells grown in Todd-Hewitt broth (THB) medium supplemented with 0.25 mM Zn and sequenced using Illumina NextSeq500.
Project description:Total RNA was isolated from mid-log phase Streptococcus agalactiae 874391 wild-type cells grown in Todd-Hewitt broth (THB) medium supplemented with 0.5 mM Cu and sequenced using Illumina NextSeq500
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.
Project description:Early onset sepsis due to Group B streptococcus (GBS) leads to neonatal morbidity, increased mortality and long term neurological deficencies. Interaction between septicemic GBS and confluent monlayers of human coronary artery endothelial cells (HCAEC) was analyzed by a genome wide expression profiling. Regulation of selected genes and proteins identified in the gene array analysis was confirmed by Real Time RT-PCR assay (Granulocyte chemotactic protein 2 (CXCL6)), ELISA (Urokinase, Cyclooxygenase 2 (COX2), Granulocyte chemotactic protein 1 (IL8)) and Western Blotting (Heme oxygenase1, BCL2 interacting protein (BIM)) at various time points between 4 and 24 hours. In total, 124 genes were differentially regulated (89 upregulated, 35 downregulated) based on a more than 3-fold difference to unstimulated HCAEC. Regulated genes are involved in apoptosis, hemostasis, oxidative stress response, infection and inflammation. We confirmed upregulation of urokinase (UPA), COX2, HMOX1 and BCL2 interacting protein and downregulation of CXCL6 and IL8. These results indicate that GBS infection might lead to impaired function of the innate immune system and might contribute to hemorrhagic and inflammatory complications during GBS sepsis. Keywords: stimulated HCAEC (with S. agalactiae) vs unstimulated control cells