Unknown,Transcriptomics,Genomics,Proteomics

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Differential expression of E.coli mar/rob/soxS triple mutant and wild type in a mouse model of pyelonephritis

ABSTRACT: Mutation of marA, rob, and soxS causes a clinical strain of E.coli to be attenuated at d3 post-infection in a mouse model of pyelonephritis, here we extract RNA at d2 post infection to analyze transcriptional differences between the two strains. In order to purify enough bacterial RNA to perform microarray, we chose a time point (day 2 post-infection) just before the triple mutant begins to decrease in bacterial load. Mouse kidneys were extracted, homogonized, and samples were pooled in RNALater (Ambion) before extraction and analysis of the transcriptomes

ORGANISM(S): Escherichia coli

SUBMITTER: Douglas Warner

PROVIDER: E-GEOD-23417 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The aquaculture industry has confronted severe economic losses due to infectious diseases in the last years. Piscirickettsiosis or Salmonid Rickettsial Septicaemia (SRS) is the bacterial disease caused by Piscirickettsia salmonis. This Gram-negative, non-motile, cellular pathogen has the ability to infect, survive, replicate, and propagate in salmonid monocytes/macrophages generating a systemic infection characterized by the colonization of several organs including kidney, liver, spleen, intestine, brain, ovary and gills. In this study, we attempted to determine whether global gene expression differences can be detected in different genetic groups of Atlantic salmon as a result of Piscirickettsia salmonis infection. Moreover, we sought to characterize the fish transcriptional response in order to reveal the mechanisms that might confer resistance in Atlantic salmon to an infection with Piscirickettsia salmonis. In doing so, after challenging with Piscirickettsia salmonis, we selected the families with the highest (HS) and the lowest (LS) recorded susceptibility for gene expression analysis using 32K cGRASP microarrays. Our results revealed in LS families expression changes are linked to iron depletion, as well as, low contents of iron in kidney cells and low bacterial load, indicated that the iron-withholding strategy of innate immunity is part of the mechanism of resistance against Piscirickettsia salmonis. This information contributes to elucidate the underlying mechanisms of resistance to Piscirickettsia salmonis infection in Atlantic salmon and to identify new candidate genes for selective breeding programmes. Forty full-sibling families of Atlantic salmon (Salmo salar) were infected by intraperitoneal injection with 0.2 mL Piscirickettsia salmonis (PS889, isolated from Oncorhynchus kisutch, 1M-CM-^W104 PFU/mL). After forty days, the fishes were harvested and the cumulative mortality (dead fish / total fish) for each family was calculated. For the second challenge, the six families with the highest cumulative mortality levels were considered of relatively high susceptibility (HS) and the six families with the lowest cumulative mortality levels were considered of relatively low susceptibility (LS) to the infection. Five control and five infected fish from three HS and three LS families were analyzed. For each HS and LS family, pools of RNA from control and infected fish were prepared separately and were reverse transcribed. Four slides were for each used family hybridized including two dye-swaped slides. Labeled samples were hybridized on a 32K cDNA microarray, developed at the Consortium for Genomics Research on All Salmonids Project (cGRASP), GEO accession number: GPL8904.

Project description:The aquatic orthomyxovirus infectious salmon anemia virus (ISAV) is an important pathogen for salmonid aquaculture, however little is known about protective and pathological host responses to infection. We have investigated intracellular responses during cytopathic ISAV infection in the macrophage-like Atlantic salmon kidney (ASK) cell line by microarray analysis (1.8K SFA2.0 immunochip) and a functional assay for glutathione. Gene transcription changed rapidly and consistently with time and with minor differences between two virus isolates. While several pro-inflammatory and antiviral immune genes were induced, genes involved in cell signaling and integrity were down-regulated, suggesting isolation of infected cells from cell-to-cell interaction and responses to external signals. Differential expression of genes regulating cell cycle and apoptosis implied opposite cues from host cell and virus. This was in pace with massive down-regulation of genes involved in biosynthesis and processing of nucleotides and nucleic acids. Significant down-regulation of several genes involved in metabolism of reactive oxygen species suggested increased oxidative stress, which was confirmed by a functional assay showing reduced levels of glutathione during infection. Testing of expression data against a microarray database containing diverse experiments revealed candidate marker genes for ISAV infection. Our findings provide novel insight into cellular host responses and determinants for acute cytopathic ISAV infection. Keywords: Infectious salmon anemia virus (ISAV); Host response; Molecular pathology; Microarray; Macrophage; Oxidative stress ASK cells infected with ISAV isolate 2 and 4 and mock-infected were cultured in triplicates and total RNA pooled from each at the following time-points post-infection; 1, 3 and 5 days. For microarray analysis, single-slide hybridisation was applied between infected RNA (Cy5 labelled) and control RNA (Cy3 labelled) for each time-point. Results were verified by real-time qPCR.

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Differential expression of E.coli mar/rob/soxS triple mutant and wild type in a mouse model of pyelonephritis

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