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Probing bacterial metabolism during infection using high-resolution transcriptomics.

ABSTRACT: A fundamental aspect of most infectious diseases is the need for the invading microbe to proliferate in the host. However, little is known about the metabolic pathways required for pathogenic microbes to colonize and persist in their hosts. In this study, we used RNA sequencing (RNA-seq) to generate a high-resolution transcriptome of the opportunistic pathogen Aggregatibacter actinomycetemcomitans in vivo. We identified 691 A. actinomycetemcomitans transcriptional start sites and 210 noncoding RNAs during growth in vivo and as a biofilm in vitro. Compared to in vitro biofilm growth on a defined medium, ?14% of the A. actinomycetemcomitans genes were differentially regulated in vivo. A disproportionate number of genes coding for proteins involved in metabolic pathways were differentially regulated in vivo, suggesting that A. actinomycetemcomitans in vivo metabolism is distinct from in vitro growth. Mutational analyses of differentially regulated genes revealed that formate dehydrogenase H and fumarate reductase are important A. actinomycetemcomitans fitness determinants in vivo. These results not only provide a high-resolution genomic analysis of a bacterial pathogen during in vivo growth but also provide new insight into metabolic pathways required for A. actinomycetemcomitans in vivo fitness.

SUBMITTER: Jorth P

PROVIDER: S-EPMC3811578 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Probing bacterial metabolism during infection using high-resolution transcriptomics.

Jorth Peter P Trivedi Urvish U Rumbaugh Kendra K Whiteley Marvin M

Journal of bacteriology 20130823 22

A fundamental aspect of most infectious diseases is the need for the invading microbe to proliferate in the host. However, little is known about the metabolic pathways required for pathogenic microbes to colonize and persist in their hosts. In this study, we used RNA sequencing (RNA-seq) to generate a high-resolution transcriptome of the opportunistic pathogen Aggregatibacter actinomycetemcomitans in vivo. We identified 691 A. actinomycetemcomitans transcriptional start sites and 210 noncoding R ...[more]

PMID: 23974023

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Project description:BackgroundRecent epidemics have entailed global discussions on revamping epidemic control and prevention approaches. A general consensus is that all sources of data should be embraced to improve epidemic preparedness. As a disease transmission is inherently governed by individual-level responses, pathogen dynamics within infected hosts posit high potentials to inform population-level phenomena. We propose a multiscale approach showing that individual dynamics were able to reproduce population-level observations.MethodsUsing experimental data, we formulated mathematical models of pathogen infection dynamics from which we simulated mechanistically its transmission parameters. The models were then embedded in our implementation of an age-specific contact network that allows to express individual differences relevant to the transmission processes. This approach is illustrated with an example of Ebola virus (EBOV).ResultsThe results showed that a within-host infection model can reproduce EBOV's transmission parameters obtained from population data. At the same time, population age-structure, contact distribution and patterns can be expressed using network generating algorithm. This framework opens a vast opportunity to investigate individual roles of factors involved in the epidemic processes. Estimating EBOV's reproduction number revealed a heterogeneous pattern among age-groups, prompting cautions on estimates unadjusted for contact pattern. Assessments of mass vaccination strategies showed that vaccination conducted in a time window from five months before to one week after the start of an epidemic appeared to strongly reduce epidemic size. Noticeably, compared to a non-intervention scenario, a low critical vaccination coverage of 33% cannot ensure epidemic extinction but could reduce the number of cases by ten to hundred times as well as lessen the case-fatality rate.ConclusionsExperimental data on the within-host infection have been able to capture upfront key transmission parameters of a pathogen; the applications of this approach will give us more time to prepare for potential epidemics. The population of interest in epidemic assessments could be modelled with an age-specific contact network without exhaustive amount of data. Further assessments and adaptations for different pathogens and scenarios to explore multilevel aspects in infectious diseases epidemics are underway.

Project description:The pathophysiology of epilepsy underlies a complex network dysfunction between neurons and glia, the molecular cell type-specific contributions of which remain poorly defined in the human disease. In this study, we validated a method that simultaneously isolates neuronal (NEUN +), astrocyte (PAX6 + NEUN-), and oligodendroglial progenitor (OPC) (OLIG2 + NEUN-) enriched nuclei populations from non-diseased, fresh-frozen human neocortex and then applied it to characterize the distinct transcriptomes of such populations isolated from electrode-mapped temporal lobe epilepsy (TLE) surgical samples. Nuclear RNA-seq confirmed cell type specificity and informed both common and distinct pathways associated with TLE in astrocytes, OPCs, and neurons. Compared to postmortem control, the transcriptome of epilepsy astrocytes showed downregulation of mature astrocyte functions and upregulation of development-related genes. To gain further insight into glial heterogeneity in TLE, we performed single cell transcriptomics (scRNA-seq) on four additional human TLE samples. Analysis of the integrated TLE dataset uncovered a prominent subpopulation of glia that express a hybrid signature of both reactive astrocyte and OPC markers, including many cells with a mixed GFAP + OLIG2 + phenotype. A further integrated analysis of this TLE scRNA-seq dataset and a previously published normal human temporal lobe scRNA-seq dataset confirmed the unique presence of hybrid glia only in TLE. Pseudotime analysis revealed cell transition trajectories stemming from this hybrid population towards both OPCs and reactive astrocytes. Immunofluorescence studies in human TLE samples confirmed the rare presence of GFAP + OLIG2 + glia, including some cells with proliferative activity, and functional analysis of cells isolated directly from these samples disclosed abnormal neurosphere formation in vitro. Overall, cell type-specific isolation of glia from surgical epilepsy samples combined with transcriptomic analyses uncovered abnormal glial subpopulations with de-differentiated phenotype, motivating further studies into the dysfunctional role of reactive glia in temporal lobe epilepsy.

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Probing bacterial metabolism during infection using high-resolution transcriptomics.

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Probing bacterial metabolism during infection using high-resolution transcriptomics.

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