Project description:Burkitt lymphoma cells can be latently infected with Epstein-Barr virus (EBV). The virus may be activated into its lytic cycle by small molecules, such as sodium butyrate. Other molecules, such as valproate and valpromide, block viral lytic reactivation. These pharmacological agents alter the cellular physiology that controls viral lytic gene expression. Changes in the cellular transcription were measured in response to one activator and two inhibitors of the Epstein-Barr virus lytic cycle in order to identify cellular genes that are potential regulators of the viral life cycle.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The RNA-seq data below show that the second block causes a decrease in expression of late but not early lytic genes.
Project description:Epstein-Barr virus (EBV) has a lifelong latency period after initial infection. Rarely, however, when the EBV immediate early gene BZLF1 is expressed by a specific stimulus, the virus switches to the lytic cycle to produce progeny viruses. We found that EBV infection reduced levels of various ceramide species in gastric cancer cells. As ceramide is a bioactive lipid implicated in the infection of various viruses, we assessed the effect of ceramide on the EBV lytic cycle. Treatment with C6-ceramide (C6-Cer) induced an increase in the endogenous ceramide pool and increased production of the viral product as well as BZLF1 expression. Treatment with the ceramidase inhibitor ceranib-2 induced EBV lytic replication with an increase in the endogenous ceramide pool. The glucosylceramide synthase inhibitor Genz-123346 inhibited C6-Cer-induced lytic replication. C6-Cer induced ERK1/2 and CREB phosphorylation, c-JUN expression, and accumulation of the autophagosome marker LC3B. Treatment with MEK1/2 inhibitor U0126 or autophagy initiation inhibitor 3-MA suppressed C6-Cer-induced EBV lytic replication. In contrast, the autophagosome-lysosome fusion inhibitor chloroquine induced BZLF1 expression. Transfection with siCREB reduced ERK1/2 phosphorylation and C6-Cer-induced BZLF1 expression. On the other hand, siJUN transfection did not affect BZLF1 expression. Our results show that increased endogenous ceramide and glycosyl ceramide (GlyCer) following C6-Cer treatment induce EBV lytic replication in gastric cancer cells via ERK1/2 and CREB phosphorylation and autophagosome accumulation.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The ChIP-seq data below show that the BET proteins bind to both EBV lytic origins of replication.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The ChIP-seq data below show that the BET proteins bind to both EBV lytic origins of replication.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The sequenced total DNA data below show that JQ1 and I-BET cause a decrease in EBV genome replication after induction.
Project description:Epstein Barr virus (EBV) replication contributes to multiple human diseases, including infectious mononucleosis, nasopharyngeal carcinoma, B-cell lymphomas, and oral hairy leukoplakia. We performed systematic quantitative analyses of temporal changes in host and EBV proteins during lytic replication to gain novel insights into virus-host interactions, using conditional Burkitt lymphoma models of type I and II EBV infection. We quantified profiles of >8000 cellular and 69 EBV proteins, including >500 plasma membrane proteins, providing temporal views of the lytic B-cell proteome and EBV virome. Our approach revealed EBV-induced remodelling of cell cycle, innate and adaptive immune pathways, including upregulation of the complement cascade and proteasomal degradation of the B-cell receptor complex, conserved between EBV types I and II. Cross-comparison with proteomic analyses of human cytomegalovirus infection and of a Kaposi sarcoma associated herpesvirus immunoevasin identified host factors targeted by multiple herpesviruses. Our results provide an important resource for studies of EBV replication.
Project description:Lytic infection by the Epstein-Barr virus (EBV) poses numerous health risks, such as infectious mononucleosis and lymphoproliferative disorder. We demonstrate that JQ1 and other BET inhibitors block two different steps in the sequential cascade of the EBV life cycle: expression of the immediate-early gene BZLF1 and lytic genome replication. This represents a novel mode of action for antiviral drugs that may increase efficacy and decrease emergence of resistance. The ChIP-seq data below show that the BET proteins bind to both EBV lytic origins of replication.
Project description:Lytic activation from latency is a key transition point in the life cycle of herpesviruses. Epstein-Barr virus (EBV) is a human herpesvirus that can cause lymphomas, epithelial cancers, and other diseases, most of which require the lytic cycle. While the lytic cycle of EBV can be triggered by chemicals and immunologic ligands, the lytic cascade is only activated when expression of the EBV latency-to-lytic switch protein ZEBRA is turned on. ZEBRA then transcriptionally activates other EBV genes and together with some of those gene products ensures completion of the lytic cycle. However, not every latently-infected cell exposed to a lytic trigger turns expression of ZEBRA on, resulting in responsive and refractory subpopulations. What governs this dichotomy? By examining the nascent transcriptome following exposure to a lytic trigger, we find that several cellular genes are transcriptionally upregulated temporally upstream of ZEBRA. These genes regulate lytic susceptibility to variable degrees in latently-infected cells that respond to mechanistically distinct lytic triggers. While increased expression of these cellular genes defines a pro-lytic state, such upregulation also runs counter to the well-known mechanism of viral nuclease-mediated host shut-off that is activated downstream of ZEBRA. Furthermore, a subset of upregulated cellular genes is transcriptionally repressed downstream of ZEBRA, indicating an additional mode of virus-mediated host shut-off through transcriptional repression. Thus, increased transcription of a set of host genes contributes to a pro-lytic state that allows a subpopulation of cells to support the EBV lytic cycle.