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Gene expression in primate liver during viral hemorrhagic fever.

ABSTRACT: Rhesus macaques infected with lymphocytic choriomeningitis virus (LCMV) provide a model for human Lassa fever. Disease begins with flu-like symptoms and progresses rapidly with fatal consequences. Previously, we profiled the blood transcriptome of LCMV-infected monkeys (M. Djavani et al J. Virol. 2007) showing distinct pre-viremic and viremic stages that discriminated virulent from benign infections. In the present study, changes in liver gene expression from macaques infected with virulent LCMV-WE were compared to gene expression in uninfected monkeys as well as to monkeys that were infected but not diseased.Based on a functional pathway analysis of differentially expressed genes, virulent LCMV-WE had a broader effect on liver cell function than did infection with non-virulent LCMV-Armstrong. During the first few days after infection, LCMV altered expression of genes associated with energy production, including fatty acid and glucose metabolism. The transcriptome profile resembled that of an organism in starvation: mRNA for acetyl-CoA carboxylase, a key enzyme of fatty acid synthesis was reduced while genes for enzymes in gluconeogenesis were up-regulated. Expression was also altered for genes associated with complement and coagulation cascades, and with signaling pathways involving STAT1 and TGF-beta.Most of the 4500 differentially expressed transcripts represented a general response to both virulent and mild infections. However, approximately 250 of these transcripts had significantly different expression in virulent infections as compared to mild infections, with approximately 30 of these being differentially regulated during the pre-viremic stage of infection. The genes that are expressed early and differently in mild and virulent disease are potential biomarkers for prognosis and triage of acute viral disease.

SUBMITTER: Djavani M

PROVIDER: S-EPMC2657139 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature

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Gene expression in primate liver during viral hemorrhagic fever.

Djavani Mahmoud M Crasta Oswald R OR Zhang Yan Y Zapata Juan Carlos JC Sobral Bruno B Lechner Melissa G MG Bryant Joseph J Davis Harry H Salvato Maria S MS

Virology journal 20090212

<h4>Background</h4>Rhesus macaques infected with lymphocytic choriomeningitis virus (LCMV) provide a model for human Lassa fever. Disease begins with flu-like symptoms and progresses rapidly with fatal consequences. Previously, we profiled the blood transcriptome of LCMV-infected monkeys (M. Djavani et al J. Virol. 2007) showing distinct pre-viremic and viremic stages that discriminated virulent from benign infections. In the present study, changes in liver gene expression from macaques infected ...[more]

PMID: 19216742

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Project description:Rhesus macaques (Macaca mulatta) infected with a lethal dose of lymphocytic choriomeningitis virus-strain WE (LCMV-WE) provide a model for Lassa fever virus infection of man. Like Lassa fever in human beings, disease begins with flu-like symptoms but can progress to morbidity fairly rapidly. Previously, we profiled the blood transcriptome of LCMV-infected monkeys (M. Djavani et al. J. Virol. 2007: PMID 17522210) showing distinct pre-viremic and viremic stages that discriminated between virulent and benign infections. In the present study, changes in liver gene expression from macaques infected with virulent LCMV-WE were compared to gene expression in uninfected monkeys as well as to monkeys that were infected but not diseased. We observed gene expression changes that occurred before the viremic stage of the disease, and could potentially serve as biomarkers that discriminate between exposure to a hemorrhagic fever virus and exposure to a benign virus. Based on a functional pathway analysis of differentially expressed genes, virulent LCMV-WE had a much broader effect on liver cell function than non-virulent virus. During the first few days of infection, virulent virus impacted gene expression associated with the generation of energy, such as fatty acid metabolism and glucose metabolism, with the complement and coagulation cascades, and with steroid metabolism, MAPK signaling and cell adhesion. For example, the energy profile resembled that of an organism entering starvation: acetyl-CoA carboxylase, a key enzyme of fatty acid synthesis, was shut down and gene products involved in gluconeogenesis were up-regulated. In conclusion, this study identifies several potential gene markers of LCMV-WE-associated liver disease and contributes to the database of gene expression changes correlated with LCMV pathogenesis in primates. 6 groups: uninfected controls, LCMV-WE infected (pre-viremic; day 1 to day 3), LCMV-WE infected (viremic; day 4 to day 7), LCMV-WE infected (post-viremic; day 8 to day 12), LCMV-Armstrong (LCMV-ARM; non-virulent strain) infected, and LCMV-ARM/LCMV-WE infected but not diseased. Each sample is from the liver of a different rhesus macaque.

Project description:Lassa fever virus is a zoonotic pathogen that plagues the endemic areas of West Africa. Rhesus macaques infected with a related arenavirus, LCMV-WE, serve as a model for Lassa-infection of human beings. Using a dose similar to that expected from a needle-stick, monkeys experience an early pre-viremic phase (day 1-3), a viremic phase with febrile onset (day 4-7), and, like human beings who succumb, they die within two weeks. Our goal was to monitor changes in gene expression that parallel disease progression in an effort to 1) identify genes with altered expression after infection, 2) identify genes that could discriminate between a virulent and non-virulent infection, and 3) identify genes encoding products that could serve as treatment targets for FDA-approved pharmaceuticals. Genes related to all three of these categories have been identified and some have been given preliminary validation by quantitative PCR and proteomic studies. These genes will be valuable candidates for future validation as prognostic biomarkers; We used microarrays to detail the global programme of gene expression underlying cellularisation and identified distinct classes of up-regulated genes during this process. Experiment Overall Design: Rhesus macaques inoculated with a lethal dose of LCMV-WE were used to model human infection with Lassa fever virus (Lukashevich et al 2002, 2003; Rodas et al 2004). To identify molecular events that occur during the first few days of virus exposure, we monitored gene expression in peripheral blood mononuclear cell (PBMC) samples by microarray analysis. Approximately 150 samples from 23 different rhesus macaques (Table 1) were hybridized to Affymetrix U133 chips. Experiment Overall Design: Affymetrix U133 arrays cover the entire human genome with approximately 54,000 gene fragments representing approximately 22,000 genes. The use of these human arrays for macaque transcriptome analysis has been validated by other laboratories (Ace et al, 2004 Wang et al, 2004), i.e. 99.8% of the array elements for which human DNA gave a signal >1.4-fold over background were also >1.4 over background for macaque DNA (Rubins et al, 2004). LCMV-infected blood samples were compared to uninfected controls and genes with over two-fold change in expression were designated âdifferentially expressedâ (Fig. 1). Thus, out of 54,000 elements, 8410 (16%) were differentially regulated with a >2-fold change in expression [supplementary Table 1 has these genes in order of the magnitude of their differential expression]. Experiment Overall Design: Virus was detectable in these monkeys at day 4 after infection by plaque assay and by RT-PCR of blood cDNA (Djavani et al 2005). Although virus is replicating in monocytes, endothelial cells, liver, spleen, and peripheral lymphoid organs soon after inoculation (Rai et al, 1997; Lukashevich et al, 2002), virus is not detectable in the circulation for the first three days. Thus we define the early, pre-viremic stage as days 1-3, and a later viremic stage as days 4-7. Although the LCMV-Armstrong strain replicated as well in cell culture as LCMV-WE, the LCMV-Arm-infected monkeys did not experience viremia, i.e. viral nucleic acid were detected in tissues but virus loads were not high enough to be detected in the circulation. The Arm-infected monkeys resisted a lethal challenge with LCMV-WE, further confirming that they had been productively infected (Rodas et al, 2004). An overview of gene expression in monkeys shows a trend to down-regulate genes at the onset of viremia followed by a sharp increase in up-regulated genes. Those monkeys that did not experience viremia (Armstrong-infected) showed no dramatic down-regulation trend (Fig. 1). Over the entire study period of 7 days, the number of down-regulated genes in the WE-infected macaques was significantly more than the number seen in the Arm-infected monkeys (p < 0.005).

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Gene expression in primate liver during viral hemorrhagic fever.

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Gene expression in primate liver during viral hemorrhagic fever.

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