Project description:Background: We report the detailed development of biomarkers to predict the clinical outcome under dengue infection. Transcriptional signatures from purified peripheral blood mononuclear cells were derived from whole-genome gene-expression microarray data and validated by quantitative PCR and tested in independent samples. Methodology/Principal Findings: The study was performed on patients of a well-characterized dengue cohort from Recife, Brazil. The samples analyzed were collected prospectively from acute febrile dengue patients who evolved with different degrees of disease severity, classic dengue fever or dengue hemorrhagic fever (DHF) and compared with similar samples from other non-dengue febrile illnesses. The DHF samples were collected 2-3 days before the presentation of the plasma leakage symptoms. Differentially-expressed genes were selected by univariate statistical tests as well as multivariate classification techniques. The results showed that at early stages of dengue infection, the genes involved in effector mechanisms of innate immune response presented a weaker activation on patients who later developed hemorrhagic fever, whereas the genes involved in apoptosis were expressed in higher levels. Conclusions/Significance: Some of the gene expression signatures displayed estimated accuracy rates of more than 95%, indicating that expression profiling with these signatures may provide a useful means of DHF prognosis at early stages of infection The samples correspond to blood samples from 26 patients from a cohort in Brazil, divided into three classes, DHF, DF, ND, as follows: 18 were confirmed dengue 3, genotype III cases, among which 10 were diagnosed as dengue hemorrhagic fever (DHF) and 8 as classical dengue fever (DF), and 8 control samples (ND) from febrile patients confirmed to be not infected with dengue. None of the DHF patients presented vasculopathy signs and symptoms at the time the samples used in the functional genomic characterization were collected. At the time of collection the patients referred approximately 5 days of disease and the absence of fever was reported two to three days after enrollment. The samples from the DF, DHF and ND patients were matched to avoid significant differences regarding patient age, gender, dengue infection history and days of symptoms among the groups.

Project description:Background: Dengue virus (DENV) infection often leads to acute illness lasting 2-7 days with severity ranging from dengue fever (DF) to hemorrhagic fever (DHF) and fatal dengue shock syndrome (DSS). The dynamic changes of host responses on the gene transcription level that accompany DENV infection and differences between DF and DHF cases have been poorly understood, particularly for South American population. Methodology/Principal Findings: Supported by a longitudinal active surveillance program for dengue transmission in Maracay, Venezuela, we conducted a prospective study to investigate host responses in dengue patients. Blood specimens and clinical information were collected on a daily basis from febrile cases confirmed with DENV infection from their first day of enrollment to early defervescence together with one convalescent sample. A total of 49 and 13 study participants were defined as DF and DHF cases respectively based on their clinical and hematological information. Using convalescent specimens as baseline, day-to-day gene expression was evaluated ex vivo in peripheral blood mononuclear cells of the study participants. Two waves of gene expression were detected: the first wave peaked at day 1 from the onset of fever (day 0) then declined at days 3-4; the second wave emerged from day 4 and peaked around day 5-6. Genes associated with innate immune process, including type I interferon signaling, cytokine-mediated signaling, chemotaxis, and antiviral responses, dominated the first wave; whereas genes involved in cell cycle processes, including cell division, mitosis, DNA replication, chromosome, and spindle organization dominated the second wave. Measureable genomic markers predicted early acute, late acute and convalescent phases with 91% accuracy. Gene signatures expressed in early acute phase predicted disease severity (DF vs DHF) with 96% accuracy. Conclusions/Significance: Our study established a dynamic pattern of detailed host immune responses to DENV infection and revealed genomic signatures valuable for diagnostics purposes. Total 64 subjects representing 51 DF (dengue fever) and 13 DHF (dengue hemorrhagic fever) cases were used to study gene expression during the course of dengue acute illness. Sample information regarding Patient No., Infecting serotype, fever status (fever days or defervescent (df) days), and disease severity (DF vs DHF) were provided. The date for a sample for gene chip hybridization and image scanning was marked as Scan date. Samples from study subjects were collected once a patient was enrolled. Over 200 samples were collected. Two genechip platforms were used, the HG-focus and HG-U133plus2. A total of 168 samples were assayed on the HG-focus platform, 2 were excluded for further analysis as they failed on quality control (i.e. VFP-0003_G7_DF, VFP-0029_G1_DF samples). A total of 101 samples were assayed on the HG-U133plus2 platform, 4 were excluded for further analysis as they failed on quality control (i.e. VFP_0186_G4_DF, VFP-0213_G3_DF, VFP_0213_G5_DF, VFP_0220_G3_DHF). Data generated by HG-focus platform were used to explore significantly expressed genes in individual Gs, phases, and for prediction analysis for disease phases. Whereas data generated by HG-U133plus2 were first used to assess the reproducibility of results generated by the HG-focus platform. Secondarily, they were used to perform prediction analysis for disease severity. Samples were grouped into stages (G) based on the timepoint when they were collected: G0=day0 (on the day of fever onset); G1=day 1 (one day after fever onset); G2=day2 (two days after fever onset)M-bM-^@M-&until G5; G6=day6-10 (6-10 days after fever onset); G7= convalescent time point (around day 28 after the first sample). Samples were also grouped into early acute (G0-G3), late acute (G4-G6) and convalescent phases (G7). References for the protocols; PMID 12803996 and 20078211

Project description:Background: Dengue virus (DENV) infection often leads to acute illness lasting 2-7 days with severity ranging from dengue fever (DF) to hemorrhagic fever (DHF) and fatal dengue shock syndrome (DSS). The dynamic changes of host responses on the gene transcription level that accompany DENV infection and differences between DF and DHF cases have been poorly understood, particularly for South American population. Methodology/Principal Findings: Supported by a longitudinal active surveillance program for dengue transmission in Maracay, Venezuela, we conducted a prospective study to investigate host responses in dengue patients. Blood specimens and clinical information were collected on a daily basis from febrile cases confirmed with DENV infection from their first day of enrollment to early defervescence together with one convalescent sample. A total of 49 and 13 study participants were defined as DF and DHF cases respectively based on their clinical and hematological information. Using convalescent specimens as baseline, day-to-day gene expression was evaluated ex vivo in peripheral blood mononuclear cells of the study participants. Two waves of gene expression were detected: the first wave peaked at day 1 from the onset of fever (day 0) then declined at days 3-4; the second wave emerged from day 4 and peaked around day 5-6. Genes associated with innate immune process, including type I interferon signaling, cytokine-mediated signaling, chemotaxis, and antiviral responses, dominated the first wave; whereas genes involved in cell cycle processes, including cell division, mitosis, DNA replication, chromosome, and spindle organization dominated the second wave. Measureable genomic markers predicted early acute, late acute and convalescent phases with 91% accuracy. Gene signatures expressed in early acute phase predicted disease severity (DF vs DHF) with 96% accuracy. Conclusions/Significance: Our study established a dynamic pattern of detailed host immune responses to DENV infection and revealed genomic signatures valuable for diagnostics purposes.

Project description:Dengue virus (DENV) infection is associated with a range of clinical manifestations, from self-limiting dengue fever (DF) to life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Although DENV-specific CD4 T cells are capable of producing inflammatory cytokines and can acquire cytotoxic functions in previously DENV-exposed individuals, much less is known related to DENV-specific CD4 T cells during acute DENV infection and disease. In this study, we set out to characterize the immune signatures of DENV-specific CD4 T cells during acute infection and investigate whether DENV-specific CD4 T cell response differs between DF and DHF. Previous studies suggest that increased IL-10 level in the blood is associated with severe dengue disease. Here we show evidence of DENV-specific IL-10-producing CD4 T cells during acute DENV infection. More specifically, an IL-10+IFN-γ+ double positive (DP) CD4 T cell population was prominent in acute hospitalized DENV cases but disappeared at the convalescent stage. RNA-sequencing analysis revealed that these cells were associated with gene signatures that marginally overlapped with previously identified signatures of cytotoxic CD4 T cells and type 1 regulatory T (Tr1)-like cells. However, the majority of the genes differentially expressed by DP cells were not related to cytotoxic CD4 T cells or Tr1-like cells. These genes include IL-21, IL-22, CD86, CD109, and CCR1, which are involved in T cell activation, function, cytokine signaling, and migration. Notably, the magnitude of DP cell response was higher in DHF than DF, whereas the gene expression profile of DP cells was similar between DF and DHF. Finally, our data show that DENV-specific DP cells are largely homogeneous based on the expression of 31 selected markers. Overall, this study reveals unique phenotypes of virus-specific IL-10/IFN-γ co-producing CD4 cells and indicates that the quantity but not quality of these cells may be positively correlated with dengue disease severity.

Project description:Background: Dengue virus (DENV) infection has a global impact on public health. The clinical outcomes (of DENV) can vary from a flu-like illness called dengue fever (DF), to a more severe form, known as dengue hemorrhagic fever (DHF). The underlying innate immune mechanisms leading to protective or detrimental outcomes have not been fully elucidated. Helper innate lymphoid cells (hILCs), an innate lymphocyte recently discovered, functionally resemble T-helper cells and are important in inflammation and homeostasis. However, the role of hILCs in DENV infection had been unexplored. Methods: We performed flow cytometry to investigate the frequency and phenotype of hILCs in peripheral blood mononuclear cells from DENV-infected patients of different disease severities (DF and DHF), and at different phases (febrile and convalescence) of infection. Intracellular cytokine staining of hILCs from DF and DHF were also evaluated by flow cytometry after ex vivo stimulation. Further, the hILCs were sorted and subjected to transcriptome analysis using RNA sequencing. Differential gene expression analysis was performed to compare the febrile and convalescent phase samples in DF and DHF. Selected differentially expressed genes were then validated by quantitative PCR. Results: Phenotypic analysis showed marked activation of all three hILC subsets during the febrile phase as shown by higher CD69 expression when compared to paired convalescent samples, although the frequency of hILCs remained unchanged. Upon ex vivo stimulation, hILCs from febrile phase DHF produced significantly higher IFN-g and IL-4 when compared to those of DF. Transcriptomic analysis showed unique hILCs gene expression in DF and DHF, suggesting that divergent functions of hILCs may be associated with different disease severities. Differential gene expression analysis indicated that hILCs function both in cytokine secretion and cytotoxicity during the febrile phase of DENV infection. Conclusions: Helper ILCs are activated in the febrile phase of DENV infection and display unique transcriptomic changes as well as cytokine production that correlate with severity. Targeting hILCs during early innate response to DENV might help shape subsequent immune responses and potentially lessen the disease severity in the future.

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Transcriptomic analysis of DENV-specific CD8+T cell responses in acute disease does not support qualitative differences as drivers of disease severity

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