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: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. Experiment Overall Design: We performed microarray-based expression analyses of splenocytes from mice infected with two virulent strains (B. abortus 2308 and B. melitensis 16M), and two different B. abortus virB mutants, whose virB operon was either disrupted (BA41) or completely deleted (ADH4.2), to better understand the contribution of the T4SS in establishing infection of the reticuloendothelial system. 3 days after infection of mice, spleens were excised for RNA extraction. For each bacterial strain, RNA from 5 mice was pooled and reverse transcribed for hybridization to an array. Each experiment was performed in duplicate.
Project description:Brucella, a notorious intracellular pathogen, causes chronic infections in many mammals, including humans. The twin-arginine translocation (Tat) pathway transports folded proteins across the cytoplasmic membrane; protein substrates translocated by Brucella include ABC transporters, oxidoreductases, and cell envelope biosynthesis proteins. Previously, we showed that a Tat mutant of Brucella melitensis M28 exhibits reduced survival within murine macrophages. In this study, we compared the host responses elicited by wild-type M28 and its Tat-mutant strains ex vivo. We utilized label-free quantitative proteomics to assess proteomic changes in RAW264.7 macrophages after infection with M28 and its Tat mutants.
Project description:Wild-type Brucella ovis ATCC 25840 requires the addition of 5% CO2 to the atmosphere to grow on either nutrient agar plates or in liquid broth culture. The goal of this study was to measure the transcriptional response of two Brucella ovis strains under high (5%) and low (0.04%) CO2. The two strains assayed were 1) wild-type and 2) a spontaneous mutant that can be cultivated in standard atmospheric levels of CO2 (~0.04%). Wild-type B. ovis harbors a single nucleotide insertion at the 3' end of a beta carbonic anhydrase gene, bcaA, which renders it non-functional. The spontaneous mutant lost this nucleotide insertion, which restored the consensus reading frame and results in a functional BcaA protein.
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: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. We analyzed altered transcription in RAW 264.7 cells at 0, 6, 12, and 24 h following the infection with 10 MOI of Brucella abortus wild and mutant strains.
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:Transcription profiling by array of two Caenorhabditis elegans dnj-14 mutant strains compared to two control strains, N2 (Bristol) wild-type and CZ1200