Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Temporal gene expression analysis of the Brucella melitensis-infected bovine Peyer's patch

ABSTRACT: In a time course study, we characterized global gene expression profile of B. melitensis-infected bovine Peyer patches in the first 4 h p.i. Microarray analysis revealed that 2,916 bovine genes were detected as differentially expressed (z-score p < 0.025) in loops inoculated with virulent B. melitensis 16M compared with controls between 15 min and 4 h post-infection. From these genes, 2,286 (78%) were up- and 630 (22%) were down-regulated. Specific genes and biological processes identified in this study will further help elucidate how both host and Brucella interact during the early infectious process to the eventual benefit of the pathogen and to the detriment of the naM-CM-/ve host. Microarrays were used to examine the transcriptional profiles of bovine intestinal Peyer patches infected with wild type Brucella melitensis 16M across five time points (15 min, 30 min, 1, 2 and 4 hours). Intestinal loops inoculated with cell culture medium were used as a control. Experiments were performed in quadruplicate (bovine ligated ileal loops surgeries were performed with four calves), generating a total of 40 arrays.

ORGANISM(S): Bos taurus

SUBMITTER: Leslie Adams

PROVIDER: E-GEOD-41835 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Mycobacterium avium subspecies paratuberculosis (MAP) infection is established following the ingestion of bacteria, their penetration of the intestinal mucosa and subsequent events of the host-parasite interaction. These bacteria invade M cells, macrophages and are capable of resisting host defenses and multiply to reach very high numbers intracellular. Mycobactrium avium subsp. avium (MAA) is an antigenically and genetically similar organisms but is relatively nonpathogenic for cattle. MAA organisms appear to infect cattle, but unlike cattle infected with MAP, cattle infected with MAA typically mount an effective systemic immune response, form caseous granuloma, and eliminate the infection. This study was designed to understand the similarities and differences in the host responses during MAP and MAA infection. Neonatal calves were infected (ligated ileal loops) with PBS, MAP, or avirulent MAA following which samples were collected at 30 min, 1h, 2h, 4h, 8h, or 12h. Post-infection, RNA was collected, processed, and then hybridized to custom bovine gene expression arrays, each of which represented 13,258 transcripts spotted in duplicate. Arrays were normalized by scaling against the average reference intensity value (i.e., average across all arrays), normalized by global mean, and then log transformed before statistical analyses were performed. Pairwise comparisons of averaged signal values and StudentM-bM-^@M-^Ys t test were performed using GeneSifter software (VizX Labs, Seattle, WA). A fold-change of at least 1.5-fold and a p value of 0.05 or less was required for a difference in signal to be considered statistically significant. When comparing the transcriptional responses of calves infected with the MAA versus MAP, unique patterns of expression were clearly visible. In general, numbers of transcripts altered in response to infection were much greater for MAA-infected animals than for those infected with the MAP. No genes were significantly up-regulated in MAP-infected animals at the earliest time point tested (30 min), and only modest numbers of genes were increased in expression over the experimental time course. On the other hand, up-regulated transcripts were detected by 30 min in MAA-infected animals and peaked by 2 hr. Differences in the numbers of down-regulated genes between MAP-infected and MAA-infected animals (compared to PBS-infected controls) were less pronounced. At the earliest time points, MAP-infected calves had a greater number of down-regulated genes than did animals infected with MAA. This trend was reversed at 8 and 12 hr post-infection. Keywords: Gene expression profiling by microarray Microarrays were used to examine the transcriptional profiles of bovine intestinal mucosa inoculated with PBS, MAP or MAA and across six time points (30 min, 1, 2, 4, 8, and 12 hours). Experiments were performed in quadruplicate for PBS, MAP, and MAA (bovine ligated ileal loops surgeries were performed with four calves). For one surgery, MAA was used for 4 time ponts only, thus generateing a total of 70 arrays.

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Temporal gene expression analysis of the Brucella melitensis-infected bovine Peyer's patch

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