Project description:Infection by neurotropic virus Japanese Encephalitis Virus (JEV) is characterized by profound neuronal cell death and neuroinflammation. Long non-coding RNAs (lncRNAs) are critical regulatory players in diverse biological processes, including viral pathogenesis. We use whole transcriptomic sequencing to identify a lncRNA JINR1 (JEV-induced non-coding RNA 1) induced upon JEV infection in neuronal cells. Transcription factor NF-κB triggers JINR-1 expression during JEV infection. Loss of JINR-1 impairs virus replication and reduces JEV-induced neuronal cell death and expression of genes involved in ER stress and neuroinflammation. Mechanistically, JINR1 inhibits the expression of mir-216-5p, which inhibits host factors GRP78 and c-JUN and the viral genome. In line with its role as a pro-viral host factor, JINR1 interacts with RBM10 and NF-κB to promote the expression of genes involved in ER stress and neuroinflammation. Our results suggest a role for JINR-1 in promoting JEV-induced cell death and neuroinflammation.
Project description:The cellular transcriptomes of VZV-infected fibroblasts and T-lymphocytes have been reported, but not that of human neurons. In order to determine the transcriptional response of human neurons to VZV infection, we generated 95%-pure populations of neurons from hESC, infected them with recombinant GFP-expressing cell-free VZV, and compared their transcriptome to that of human foreskin fibroblasts infected in parallel, using Agilent microarrays. Applying a twofold-change as the cutoff (p-value<0.05), we observed that transcription of 1654 fibroblast and 340 neuronal genes were upregulated, and 955 fibroblast and 38 neuronal genes were downregulated by VZV infection. 223 of these infection-regulated genes were unique to neurons. Gene ontology enrichment analysis revealed several clusters of genes regulated by VZV in neurons and fibroblasts differed. For example, neurons did not show upregulation of innate immune responses, NF-kappaB, response to stress and DNA repair clusters, in contrast to fibroblasts that upregulated these groups. This is the first study of the response of genetically normal human neurons to viral infection. Two-condition experiment, VZV-GFP23- fibroblast cells vs. fibroblast cells, and VZV-GFP23- neuron cells vs. neuron cells. Data from two biological replicates and two technical replicates were used for each condition.
Project description:Following genital HSV-1 infection in mice, virus spreads to and infects the sensory neurons of the dorsal root ganglia (DRG) and the enteric neurons situated within the large intestinal musculara (LIM). We used RNA sequencing to simultaneously study the host and viral transcriptomes at these two distinct sites of infection. We find that transcription across the HSV-1 genome is weak and incomplete in sensory neurons whereas all known HSV-1 coding genes are robustly expressed in the enteric neurons. Furthermore, a T cell activation signature dominated the immune response to HSV-1 infection in the DRG. In contrast, an innate inflammatory signature was observed in the LIM.
Project description:Loss of RNA homeostasis underlies numerous neurodegenerative and neuroinflammatory diseases. However, the molecular mechanisms that trigger neuroinflammation are poorly understood. Viral double-stranded RNA (dsRNA) triggers innate immune responses when sensed by host pattern recognition receptors (PRRs) present in all cell types. Here, we report that human neurons intrinsically carry exceptionally high levels of immunostimulatory dsRNAs and identify long 3'UTRs as giving rise to neuronal dsRNA structures. We found that the neuron-enriched ELAVL family of genes (ELAVL2, -3, -4) can increase 1) 3'UTR length, 2) dsRNA load, and 3) activation of dsRNA-sensing PRRs such as MDA5, PKR, and TLR3. In wild-type neurons, neuronal dsRNAs signaled through PRRs to induce tonic production of the antiviral type I interferon. Depleting ELAVL2 in WT neurons led to global shortening of 3'UTR length, reduced immunostimulatory dsRNA levels, and rendered WT neurons susceptible to herpes simplex virus and Zika virus infection. Neurons deficient in ADAR1, a dsRNA-editing enzyme mutated in the neuroinflammatory disorder Aicardi-Goutières syndrome, exhibited intolerably high levels of dsRNA that triggered PRR mediated toxic inflammation and neuronal death. Depleting ELAVL2 in ADAR1 knockout neurons led to prolonged neuron survival by reducing immunostimulatory dsRNA levels. In summary, neurons are specialized cells where PRRs constantly sense ‘self’ dsRNAs to pre-emptively induce protective antiviral immunity, but maintaining RNA homeostasis is paramount to prevent pathological neuroinflammation.
Project description:The cellular transcriptomes of VZV-infected fibroblasts and T-lymphocytes have been reported, but not that of human neurons. In order to determine the transcriptional response of human neurons to VZV infection, we generated 95%-pure populations of neurons from hESC, infected them with recombinant GFP-expressing cell-free VZV, and compared their transcriptome to that of human foreskin fibroblasts infected in parallel, using Agilent microarrays. Applying a twofold-change as the cutoff (p-value<0.05), we observed that transcription of 1654 fibroblast and 340 neuronal genes were upregulated, and 955 fibroblast and 38 neuronal genes were downregulated by VZV infection. 223 of these infection-regulated genes were unique to neurons. Gene ontology enrichment analysis revealed several clusters of genes regulated by VZV in neurons and fibroblasts differed. For example, neurons did not show upregulation of innate immune responses, NF-kappaB, response to stress and DNA repair clusters, in contrast to fibroblasts that upregulated these groups. This is the first study of the response of genetically normal human neurons to viral infection.
Project description:The apicomplexan parasite Toxoplasma gondii infects a broad range of different cell types in avian and mammalian hosts including humans. Infection of immunocompetent hosts is mostly asymptomatic or benign, but leads to development of largely dormant bradyzoites that persist for the hosts life predominantly within neurons and muscle cells. Here we have analyzed the impact of the host cell type on the co-transcriptomes of host and parasite using high-throughput RNA sequencing. Murine cortical neurons and astrocytes, skeletal muscle cells (SkMCs) and fibroblasts differed by more than 16,200 differentially expressed genes (DEGs) before and at 24 hours after infection with T. gondii. However, only 157 to 492 of these DEGs were regulated within the different cell types by infection. Intriguingly, largely diverse sets of genes were regulated in neurons, SkMCs, astrocytes and fibroblasts following infection indicating host cell type-specific transcriptional responses. Only a few genes were identified that were commonly regulated in two or three host cell types after infection. The heterogeneous transcriptomes of the host cells before and during infection coincided with the differential expression of ~5,400 genes in T. gondii residing in the different host cells. Expression of these DEGs mostly differed quantitatively but within neurons, T. gondii also expressed 121 genes in a strictly host cell-type specific manner. Interestingly, we identified gene clusters in both T. gondii and its host, which correlated with the predominant parasite persistence in neurons or SkMCs as compared to astrocytes or fibroblasts. Thus, heterogeneous expression profiles of different host cell types and the parasites’ ability to adapt to them may govern the parasite-host cell interaction during toxoplasmosis.
Project description:The major inducible 70 kDa heat shock protein (hsp70) is host protective in a mouse model of measles virus (MeV) brain infection. Transgenic constitutive expression of hsp70 in neurons, the primary target of MeV infection, abrogates neurovirulence in neonatal H-2d congenic C57BL/6 mice. A significant level of protection is retained after depletion of T lymphocytes, implicating innate immune mechanisms. Focus of the present work was to elucidate the basis for hsp70-dependent innate immunity using this model. Transcriptome analysis of brains from transgenic (TG) and non-transgenic (NT) mice 5 days after infection identified type 1 interferon (IFN) signaling and macrophage activation/antigen presentation as the main differences linked to survival. The pivotal role for type 1 IFN in hsp70-mediated protection was demonstrated in mice with a genetically disrupted type 1 IFN receptor (IFNAR-/-), where IFNAR-/- eliminated the difference in survival between TG and NT mice. Brain macrophages, not neurons, are the predominant source of type 1 IFN in the virus-infected brain, and in vitro studies provided a mechanistic basis by which MeV-infected neurons can induce IFN-β in uninfected microglia in an hsp70-dependent manner. MeV infection induced extracellular release of hsp70 from mouse neuronal cells that constitutively express hsp70, and extracellular hsp70 induced IFN-β transcription in mouse microglial cells through Toll-like receptors 2 and 4. Collectively, results support a novel axis of type 1 IFN-dependent antiviral immunity in the virus-infected brain that is driven by hsp70. Hsp70 expression in mice enhances gene expression related to antiviral immune response against MeV neurovirulence. We performed microarrays on whole brain tissues in mice to obtain an unbiased picture of how hsp70 alters host innate responses to viral infection. Hsp70-overexpressing transgenic (TG) and non-transgenic (NT) mice were infected with MeV intracranially, and total brain mRNA harvested at 5 and 10 days post infection (d.p.i.) was analyzed, sampling the hemisphere opposite the side of viral inoculation. Analysis includes 6 groups: infected TG at 5 d.p.i. (n=4), infected TG at 10 d.p.i. (n=5), infected NT at 5 d.p.i. (n=4), infected NT at 10 d.p.i. (n=5), uninfected TG at 5 d.p.i. (n=4), and uninfected NT at 5 d.p.i. (n=4).
Project description:Viral infection outcomes are governed by the complex and dynamic interplay between the infecting virus population and the host response. It is increasingly clear that both viral and host cell populations are highly heterogeneous, but little is known about how this heterogeneity influences infection dynamics or viral pathogenicity. To dissect the interactions between influenza A virus (IAV) and host cell heterogeneity, we examined the combined host and viral transcriptomes of thousands of individual cells, each infected with a single IAV virion. We observed complex patterns of viral gene expression and the existence of multiple distinct host transcriptional responses to infection at the single cell level. We show that human H1N1 and H3N2 strains differ significantly in patterns of both viral and host anti-viral gene transcriptional heterogeneity at the single cell level. Our analyses also reveal that semi-infectious particles that fail to express the viral NS can play a dominant role in triggering the innate anti-viral response to infection. Altogether, these data reveal how patterns of viral population heterogeneity can serve as a major determinant of antiviral gene activation.
Project description:Virus and host factors contribute to cell-to-cell variation in viral infection and determine the outcome of the overall infection. However, the extent of the variability at the single cell level and how it impacts virus-host interactions at a systems level are not well understood. To characterize the dynamics of viral transcription and host responses, we used single-cell RNA sequencing to quantify at multiple time points the host and viral transcriptomes of human A549 cells and primary bronchial epithelial cells infected with influenza A virus. We observed substantial variability of viral transcription between cells, including the accumulation of defective viral genomes (DVGs) that impact viral replication. We show a correlation between DVGs and viral-induced variation of the host transcriptional program and an association between differential induction of innate immune response genes and attenuated viral transcription in subpopulations of cells. These observations at the single cell level improve our understanding of the complex virus-host interplay during influenza infection.
Project description:Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders. Using primary cultures and neuronal cell lines, we examined the impact of a viral protein (HIV-1 Vpr) on the expression of miRNAs and mRNAs.