Differential miRNome analysis in a dengue resistant cohort versus susceptible after Dengue Virus serotype 2 or mock in vitro infection
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ABSTRACT: MicroRNAs have emerged as relevant players in resistance to infection. We aimed to identify miRNAs involved in natural resistance to dengue infection. Two groups of people living in dengue endemic area were classified as susceptible (SD) or resistant (RD) to dengue virus (DENV) infection according to their anti-DENV antibody status. We hypothesized that anti-DENV seronegative individuals may represent a population resistant to DENV infection. The miRNome from monocytes of 7 individuals of each group was assessed upon mock- or DENV-2 infection.Dysregulated miRNAs were chosen as candidates for functional studies.
Project description:Analysis of the host response to dengue virus at gene expression level. The hypothesis tested in the present study was that dengue virus triggers and regulate different pathaway with different kinetics controlling the antiviral, the inflammatory and the apoptotic response in primary human DC. Results provide important information of the response to DC to dengue virus showing that antioxidant genes are early stimulated after denv infection reflecting an early production of reactive oxygen species. Interestingely, we demonstrated that ROS production and antiviral and apoptotic responses intersect since chemical inhibition of ROS impairs antiviral and apoptotic responses in these cells. Total RNA obtained from in vitro dengue infected primary human dendritic cells at 0, 6, 12, 18, 24 hours compared to uninfected cells at time 0
Project description:Dengue viruses (DENV) are generally maintained in a cycle which requires horizontal transmission via their arthropod vector, Ae. Aegypti, to the vertebrate host. One important consequence of this process is the interference of these arboviruses with both invertebrate and vertebrate immune systems. While infection of vertebrates causes disease, the presence of DENV gives rise to life-long, persistent infection in mosquitoes. The results of a comparative transcriptome analysis between DENV-infected and uninfected salivary glands revealed activation of both the immune deficiency (IMD) and the Toll pathways, as well as involvement of the putative antibacterial cecropin-like peptide (AAEL000598), in controlling DENV infection in Ae. aegypti. The mature form of this peptide was found to be active against DENV and Chikungunya viruses, whereas its precursor also had a strong anti-Leishmania effect. This study is the first to establish a comparative transcriptome analysis of DENV-infected and uninfected salivary glands and demonstrates that certain DENV-induced peptides, that are part of the IMD pathway, possess broad-spectrum anti-pathogenic activity and may have therapeutic potential in human. Infectious blood meals were offered to 3-day-old, adult, female Ae. aegypti Liverpool mosquitoes using a silicone membrane feeder system (Alto et al., 2005). Human blood was combined with DENV-2 16681 to provide a blood meal titer of 5.106 plaque forming units (PFU)/ml. At different time-points after the blood meal, salivary glands were dissected in acid guanidium thiocyanate-phenol-chloroform (RNAble; Eurobio, France) or phosphate-buffered saline (PBS), and the samples were frozen at -70°C until use.
Project description:MicroRNAs (miRNA) have alternative forms known as isomiRs, which differ from each other by a few nucleotides. Next generation sequencing platforms facilitate identification of these isomiRs and recent discoveries regarding their functional importance have increased our understandings of the regulatory complexities of the microRNAome. Observed changes in the miRNA profiles in mosquitoes infected with flaviviruses have implicated small RNAs in the interactions between viruses and their vectors. Here we analysed the isomiR profiles of both uninfected and infected blood fed Aedes aegypti mosquitoes with a major human pathogen, Dengue virus at two time points post-infection. We found noticeable changes to the isomiR expression profile in response to infection and aging. Data analysis revealed a distinct bias towards isomiR production in the mature miRNA as opposed to the star strand. Furthermore, we noticed that only in 40% of Ae. aegypti miRNAs, the most abundant reads for each particular miRNA match the exact sequence reported in the miRbase. The isomiR expression variations between an Ae. aegypti embryonic cell line (Aag2) and whole mosquitoes demonstrated a tissue-specific pattern of isomiR production. Our results illustrated a bias for certain types of isomiRs for each miRNA. The findings presented in this study also provide evidence that isomiR production is not a random phenomenon and may be important in DENV colonisation of its vector. Examination of isomiR production rate in DENV infected and non infected mosquitoes
Project description:Dengue virus is an + strand RNA virus. We have carried our infections of human cells with Dengue and analyzed the translation, replication, and localization of the Dengue RNA. This allowed for clear definition of the life cycle of the Dengue virus inside a host cell. We also assessed the host response to Dengue virus, finding that a large fraction of the translational response is due to Interferon function. Translational and transcriptional analysis of the cellular response to Dengue virus infection
Project description:The ability of many viruses to manipulate the host antiviral immune response often results in complex host-pathogen interactions. In order to study the interaction of dengue virus (DENV) with the Aedes aegypti immune response, we have characterized the DENV infection-responsive transcriptome of the immune-competent A. aegypti cell line Aag2. As in mosquitoes, DENV infection transcriptionally activated the cell line Toll pathway and a variety of cellular physiological systems. Most notably, however, DENV infection down-regulated the expression levels of numerous immune signaling molecules and antimicrobial peptides (AMPs). Functional assays showed that transcriptional induction of AMPs from the Toll and IMD pathways in response to bacterial challenge is impaired in DENV-infected cells. In addition, Escherichia coli, a gram-negative bacteria species, grew better when co-cultured with DENV-infected cells than with uninfected cells, suggesting a decreased production of AMPs from the IMD pathway in virus-infected cells. Pre-stimulation of the cell line with gram-positive bacteria prior to DENV infection had no effect on DENV titers, while pre-stimulation with gram-negative bacteria resulted in an increase in DENV titers. These results indicate that DENV is capable of actively suppressing immune responses in the cells it infects, a phenomenon that may have important consequences for virus transmission and insect physiology. Infected (dengue virus or heat-inactivated dengue virus) vs. naive cells. 3 replicates each.
Project description:Here; we have described and tested a microarray based-method for the screening of dengue virus (DENV) serotypes. This DNA microarray assay is specific and sensitive and can detect dual infections with two dengue virus serotypes and single-serotype infections. Other methodologies may underestimate samples containing more than one serotype. This technology can be used to discriminate between the four DENV serotypes. Single-stranded DNA targets were covalently attached to glass slides and hybridised with specific labelled probes. DENV isolates and dengue samples were used to evaluate microarray performance. Our results demonstrate that the probes hybridized specifically to DENV serotypes; with no detection of unspecific signals. This finding provides evidence that specific probes can effectively identify single and double infections in DENV samples. Background Dengue is a mosquito-borne viral infection causing a major public health problem globally. Dengue virus (DENV) is the causative agent of dengue fever (DF) and dengue hemorrhagic fever (DHF) and includes four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4). DENV-2 and DENV-3 have been associated with severe dengue disease, consequently, laboratory testing for DENV is needed to confirm the diagnosis of DENV infection, serotype and to differentiate dengue from other febrile tropical illnesses. In addition, surveillance of mosquitoes infected with DENV is needed to monitor the infection rates within vector mosquito populations harboring specific serotype to provide an early warning sign to predict epidemics. Results In this work we have applied microarray analysis to simultaneously determine the serotype of multiple RNA samples from human or mosquitoes. The proposed microarray method can be used for i) rapid and reliable dengue diagnosis; ii) serotyping and iii) surveillance of mosquitoes infected with dengue. These microarrays were useful to confirm the presence of DENV-2 in 94 serum samples, DENV-3 in three samples from Juchitan, Oaxaca and one case from Juchitan, Oaxaca contained DENV-2 and -3. Moreover by using these microarrays we also determined DENV in pools of gravid females mosquitoes collected in several sites of nineteen Mexican states in 2005. Mosquito pools from 31 cities in the states of Yucatan, Campeche, Tabasco, Chiapas, Veracruz, Oaxaca, Guerrero, Tamaulipas and Colima were infected with DENV-2, six cities in Yucatán, Tabasco, Morelos, Tamaulipas, Colima, and Nayarit with DENV-1, three from Tabasco, Veracruz and Oaxaca with DENV 3 and two with two serotypes simultaneously (Ciudad Mante with DENV-1 and DENV-2, and Tavela with DENV-2 and DENV-3). Conclusion Here we show the success of applying microarrays assay to provide a consistently robust qualitative detection of dengue serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) in serum samples from patients or in pools of gravid female mosquitoes collected in the field of nineteen Mexican states. Interestingly, we did not detect any mosquito or serum sample containing DENV-4.
Project description:Host factors are essential for efficient amplification of Dengue virus (DENV), yet the current knowledge of these cellular proteins remains limited. Here, we used quantitative thiouridine cross-linking mass spectrometry (qTUX-MS) to cross-link proteins to viral RNA during a live DENV infection in cell culture. We identified 79 novel host proteins that have not been previously implicated in DENV infection, and demonstrated the reliability of qTUX-MS by validating a subset of these factors. Analysis of proteome changes revealed critical pathways up- and down-regulated during DENV infection, while the levels of qTUX-MS identified factors remained largely unchanged. Knockdown of HMCES, RBMX and hnRNP F reduced the levels of both intracellular viral RNA and DENV titers, suggesting roles in viral amplification prior to packaging and release. In contrast, knockdown of hnRNP M or NONO caused a dramatic drop in viral titers without impacting viral RNA accumulation, indicating a role downstream of DENV replication. Importantly, none of these five host factors were essential for cell viability or amplification of an unrelated virus, adenovirus, demonstrating that knockdown of these host factors did not reduce cell fitness for viral amplification. Thus, qTUX-MS can be used to identify host factor interactions for any RNA virus.
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:Clinical symptoms of dengue virus (DENV) infection, the most prevalent arthropod-borne viral disease, range from classical mild dengue fever to severe, life-threatening dengue shock syndrome. However, most DENV infections cause few or no symptoms. Asymptomatic DENV-infected patients provide a unique opportunity to decipher the host immune responses leading to virus elimination without negative impact on an individual’s health. We used an integrated approach of transcriptional profiling and immunological analysis to compare a Cambodian population of strictly asymptomatic viremic individuals with clinical dengue patients. Whereas inflammatory pathways and innate immune response pathways were similar between asymptomatic individuals and clinical dengue patients, expression of proteins related to antigen presentation and subsequent T and B cell activation pathways were differentially regulated, independent of viral load and previous DENV infection history. Feedback mechanisms controlled the immune response in asymptomatic viremic individuals, as demonstrated by increased activation of T cell apoptosis-related pathways and FcγRIIB signaling associated with decreased anti-DENV specific antibody concentrations. Taken together, our data illustrate that symptom-free DENV infection in children is associated with determined by increased activation of the adaptive immune compartment and proper control mechanisms, leading to elimination of viral infection without excessive immune activation, with implications for novel vaccine development strategies
Project description:Dengue virus (DENV) infects hundreds of millions of people annually, yet there is only a limited knowledge of the host immune response to dengue. Here, we used a systems biological approach to perform a detailed analysis of the innate immune response to DENV infection in the whole blood samples of acutely infected humans in Bangkok, Thailand. Transcriptomic analysis revealed that genes encoding pro-inflammatory mediators and type I IFN related proteins, were associated with high levels of virus during the first few days of infection. Individuals with low or negative viremia at the late stage of fever were enriched with genes associated with pathways involved in cell cycle, proliferation, cell metabolism and translational control. Meta-analysis showed significant enrichment in genes specific for innate cells (monocytes, macrophages and DCs) in the specimens with high VL and enrichment in genes specific for NK cells, CD4+ and CD8+ T cells as well as B cells in specimens with low VL. Furthermore, flow cytometric analysis revealed an expansion in the numbers of CD14+CD16+ monocytes and depletion of CD14dimCD16++ cells and BDCA-1+ myeloid DC in blood. Consistent with this, in a non-human primate model, infection with DENV boosted the numbers of CD14+CD16+ monocytes in the blood and in secondary lymphoid organs. In vitro, freshly isolated blood monocytes infected with DENV up regulated CD16 and mediated robust differentiation of resting B cells to CD27++CD38++ plasmablasts and IgG and IgM secretion. Taken together, these data provide a detailed picture of the innate response to dengue infection in humans, and highlight an unappreciated role for CD14+CD16+ monocytes in promoting the differentiation of plasmablasts and mediating antibody response to DENV. We analyzed whole blood samples from 28 dengue patients (DF n=18, DHF=10) hospitalized at the Siriraj Hospital in Bangkok, Thailand during the season of 2009 The specimens were acquired between days 2 and 9 after onset of symptoms (acute illness), and for 19 patients (DF n=13, DHF=6) also at the convalescence at 4 weeks or later after discharge. Additionally, blood was sampled from 9 healthy, non-infected donors to provide controls for transcriptomic and immunological analysis.