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Transcriptional profiling of Brucella ovis strains cultivated in the presence of high (5%) and low (0.04%) CO2

ABSTRACT: 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.

ORGANISM(S): Brucella ovis

PROVIDER: GSE130678 | GEO | 2019/05/04

REPOSITORIES: GEO

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Project description:Brucella dynamically engage macrophages while trafficking to an intracellular replicative niche as macrophages, the first line of innate host defense, attempt to eliminate organisms. Brucella melitensis, B. neotomae, and B. ovis are highly homologous, yet exhibit a range of host pathogenicity and specificity. RAW 264.7 macrophages infected with B. melitensis, and B. ovis exhibit divergent patterns of bacterial persistence and clearance; conversely, B. melitensis and B. neotomae exhibit similar patterns of infection. Evaluating early macrophage interaction with Brucella spp. allows discovery of host entry and intracellular translocation mechanisms, rather than bacterial replication. Microarray analysis of macrophage transcript levels following a 4 hr Brucella spp. infection revealed 130 probe sets altered compared to uninfected macrophages; specifically, 72 probe sets were increased and 58 probe sets were decreased with any Brucella spp. Interestingly, much of the inflammatory response was not regulated by the number of Brucella gaining intracellular entry, as macrophage transcript levels were often equivalent among B. melitensis, B. ovis, and B. neotomae infections. An additional 33 probe sets were identified with altered macrophage transcript levels among Brucella spp. infections that may correlate with species specific host defenses and intracellular survival. Gene ontological categorization unveiled genes altered among species are involved in cell growth and maintenance, response to external stimuli, transcription regulation, transporter activity, endopeptidase inhibitor activity and G-protein mediated signaling. Host transcript profiles provide a foundation to understand variations in Brucella spp. infections, while structure of the macrophage response and intracellular niche of Brucella spp. will be revealed through piecewise consideration of host signaling pathways. Keywords: Macrophage, intracellular pathogen, Brucella melitensis, Brucella neotomae, Brucella ovis, inflammatory immune response, species specificity

Project description:The study demonstrated the gene expression through microarray analysis of total mRNA in rams experimentally infected with a rough (R) virulent strain of Brucella ovis in reproductive organs (epididymus, testicles, ampolae, vesicular glands, bulbourethral glands) and a pool of lymph nodes (inguinal and scrotal) at three different times: acute phase (60 days post challenge [dpc]), chronic phase 1 (120dpc), and chronic phase 2 (240dpc) of infection. To further define the gene expression changes associated with infected rams, the profiles of a control group (0 dpc) of rams was compared using the Affymetrix Bovine Genome Array. Of the 23,000 genes that were analyzed on the array, B. ovis infection in rams’ tissues revealed 139, 930 and 744 Differentially Expressed Genes (DEGs) in the acute, chronic 1, and chronic phase 2 of infection, respectively. Among the three phases of infection, 44 DEGs (30 known and 14 unknown genes) were expressed in common. The biological functions of immune cell trafficking, immunological disease, infectious disease, inflammatory disease, inflammatory response and cellular movement were significant at the three phases of infection. The results support the first microarray analysis of ram tissues infected with an R strain of B. ovis. A total of twelve 12-month-old healthy Santa Inês rams, previously diagnosed as negative for brucellosis/visna maedi/toxoplasmosis/neosporosis, were selected for the study. The rams were kept in an isolated pen and experimentally challenged with a rough (R) virulent B. ovis PA strain (ATCC 25840). For the experiment, the rams were classified during the course of infection according to time: 0 dpc (control), 60 dpc (acute phase), 120 dpc (chronic phase 1) and 240 dpc (chronic phase 2). For each time, the tissues epididymus, testicles, ampolae, vesicular glands, bulbourethral glands, and a pool of lymph nodes (inguinal and scrotal) were collected. Three rams were euthanized and necropsied for tissues collection purposes for each time. To define the gene expression changes associated with infected rams, the profile of a control group (0 dpc) of rams was compared using microarray technology. REPLACE This dataset includes control samples and acute phase samples.

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Transcriptional profiling of Brucella ovis strains cultivated in the presence of high (5%) and low (0.04%) CO2

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