Project description:Investigation of whole genome gene expression level changes in a Brucella melitensis delta prlr mutant compared to the wild type strain. The mutants analyzed in this study are further described in A. Mirabella, R-M Yanez, R.M. Delrue, S. Uzureau, M.S. Zygmunt, A. Cloeckaert, X. De Bolle, J.J. Letesson (2012). The two component system PrlS/PrlR of Brucella melitensis is required for persistence in mice and appears to respond to ionic strength. Microbiology
Project description:The virB operon, encoding a Type IV secretion system (T4SS), is essential for intracellular survival and persistent infection of Brucella spp. To better understand the role of the T4SS in evading host defense mechanisms and establishing chronic infection, we compared transcriptional profiles of the host response to infection with wild type Brucella strains and strains that fail to express the virB genes. Analysis of host gene expression profiles three days after inoculation with wild type Brucella strains revealed an inflammatory response dominated by interferon-induced genes. This analysis found that not only the type II but also type I interferon pathway was elicited by Brucella infection. Real time RT-PCR showed that a group of genes from these pathways was induced by day 3 post-infection and declined to baseline levels by day 7. In contrast, neither of the two virB mutant strains elicited expression of interferon-induced genes, demonstrating that the T4SS was required to trigger an inflammatory response early during infection. Keywords: analysis of transcriptional responses induced by infection
Project description:Investigation of whole genome gene expression level changes in a Brucella melitensis delta prlr mutant compared to the wild type strain. The mutants analyzed in this study are further described in A. Mirabella, R-M Yanez, R.M. Delrue, S. Uzureau, M.S. Zygmunt, A. Cloeckaert, X. De Bolle, J.J. Letesson (2012). The two component system PrlS/PrlR of Brucella melitensis is required for persistence in mice and appears to respond to ionic strength. Microbiology A six chip study using total RNA recovered from three separate wild-type cultures of Brucella melitensis 16M and three separate cultures of a prlR mutant strain. Each chip measures the expression level of 3,198 genes from Brucella melitensis 16M with nineteen 60 mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.
Project description:Investigation of whole genome gene expression level changes in a B. suis 1330 regA mutant, compared to the wild-type strain. The two-component system RegBA of Brucella suis plays a central role in the control of respiratory systems adapted to oxygen deficiency. The mutant strain is affected in long-term persistence in vitro (this study) and in chronic infection in vivo (Abdou, E et al. 2013, Infect.Immun. 81: 2053-61). Using an original “in vitro model of persistence”, we compare large-scale transcriptome of the wild-type and ∆regA strains to identify the RegA-regulon potentially involved in the set-up of the persistence state.
Project description:Many pathogenic bacteria use a regulatory process termed Quorum Sensing (QS) to produce and detect small diffusible molecules to synchronize gene expression within a population. In Gram-negative bacteria, the detection and response to these molecules depend on transcriptional regulators belonging to the LuxR family. Such a system have been discovered in the intracellular pathogen Brucella melitensis, a Gram-negative bacteria responsible for brucellosis, a word-wide zoonosis remaining a serious public health concern in endemic countries. Two LuxR-type regulators, VjbR and BabR, have been identified in the genome of this pathogen. The vjbR mutant is highly attenuated in all tested models suggesting a crucial role of QS in the virulence of Brucella. This attenuation is at least due to the involvement of VjbR in the activation of the virB operon coding for a type four secretion system essential for Brucella to reach its intracellular replication compartment. At present, no function has been attributed to BabR. To assess the role of both Brucella QS-regulators, we performed in tandem comparative transcriptomic and proteomic analyses of vjbR and babR mutants. These experiments revealed that 10% of Brucella genome is regulated through those regulators, revealing that QS is a global regulatory system in this intracellular pathogen. The overlapping between BabR and VjbR targets suggest an unexpected cross-talk between these two regulators. Moreover, our results demonstrate that VjbR and BabR regulate many gene and/or proteins involved in stress response, metabolism and virulence. These targets are potentially involved in the adaptation of Brucella to the oxidative, pH and nutritional stresses encountered within the host. These findings highlight the involvement of QS in the virulence of Brucella and led us to suggest that this regulatory system could be implied in the spatial and sequential adaptation of Brucella to the host environment. Keywords: Quorum Sensing, Comparative gene expression, Brucella melitensis
Project description:To explore the role of Brucella BI-1 in Brucella suis S2, we constructed the Brucella BI-1 deletion mutant strain and its complementary strain. We then determined the effect of Brucella BI-1 deletion on the physiological characteristics of Brucella suis S2 and revealed them via integrated transcriptomic and proteomic analyses. Brucella BI-1 deletion altered the membrane properties of Brucella suis S2 and decreased its resistance to acidic pH, H2O2, polymyxin B, and lincomycin. Additionally, deleting Brucella BI-1 led to defective growth, cell division, and viability in Brucella suis S2. In conclusion, our results revealed that Brucella BI-1 is a bacterial cytoprotective protein involved in membrane homeostasis, cell division, and stress resistance in Brucella suis S2.
Project description:We focused on whether transposon mutagenesis in Brucella abortus could induce difference in the trascriptional responses of RAW 264.7 cell infection model compared to the wild strain infected RAW 264.7 cells. The function of genes in Brucella abortus was analyzed through the identified differences in gene expression between RAW 264.7 cell infected with wild and mutant strains.
Project description:Purpose:To uncover the related mechanisms underlie virulence attenuation of Brucella canis MucR mutant strain. Methods:Three Brucella canis RM6/66 strains and three Brucella canis ΔmucR strains were grown in TSB at 37℃ until the log phase was reached, total RNA was isolated using the TRIzol according to the manufacturer’s instructions.The sequencing library of each RNA sample was prepared by using NEB Next Ultra Directional RNA Library Prep Kit for Illumina as recommended by the manufacturer. An Illumina platform was used to perform the transcriptome sequencing. Results: The results revealed that expressions of 694 genes were significantly different between RM6/66 and ΔmucR. Data analysis showed that in the COG term, the different expressed genes involved in translation, ribosomal structure and biogenesis, signal transduction mechanisms, energy production and conversion, intracellular trafficking, secretion, and vesicular transport, and extracellular structures were significantly affected. Pathway enrichment analysis indicated that the genes involved in ribosome, oxidative phosphorylation, aminoacyl-tRNA biosynthesis and protein export were significantly enriched.