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Description:
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The parallel gene expression profiles of Brucella melitensis and the host have not
been elaborated . In this study , I analyze and discuss the transcriptional profiles of B .
melitensis invasive -associated genes , the expression profile of intracellular B . melitensis
and B . melitensis -infected non -phagocytic cells in the first 12 h post -infection (PI ) , and
the in vivo temporal global transcriptome of both B . melitensis and the infected bovine
host in the first 4 h PI . The initial study found that B . melitensis at late -log phase of
growth were more invasive in non -phagocytic cells than at early -log or stationary growth
phase . Microarray -based studies identified 454 Brucella genes differentially expressed
between the most and the least invasive growth phases . Additionally , B . melitensis
strains with transposon interrupted in loci BMEII0380 (acrA ) and BMEI1538
(hypothetical protein ) were found to be deficient in internalization compare with the
wild -type strain . A second experiment was designed with the goal of characterizing host
and pathogen transcriptome in parallel . For detecting intracellular Brucella gene
expression , a combined protocol consisting of a linear amplification of sense -stranded
RNA biased to pathogen transcripts to the previously enriched host :pathogen RNA mixed sample , was developed . RNA samples were hybridized on human and Brucella
cDNA microarrays , which analysis revealed a common down -regulation transcriptional
profile at 4 h PI that was reverse at 12 h PI . The integrity of B . melitensis virB operon
and the expression of host MAPK1 were confirmed as critical for early B . melitensis
intracellular survival and replication in non -phagocytic cells . Finally , a temporal
morphological and molecular characterization of the initial B . melitensis :bovine host
interaction using a calf ileal loop model was performed . B . melitensis was isolated from
intestinal Peyer’s patches as soon as 15 min and from systemic blood after 30 min postintra
luminal inoculation . Microarray results revealed a common transcriptional profile
in Brucella , but two different transcriptional profiles were identified in the host in the
first 4 h PI . The importance of differentially expressed biological processes , pathways
and individual genes in the initial Brucella pathogenesis is discussed . |