Project description:We used microarray analysis to investigate whole genome transcriptome dynamics of the marine cyanobacterium Prochlorococcus sp. strain MED4 and the T7-like podovirus P-SSP7 over a time course during the 8 hour latent period of lytic infection prior to cell lysis. Manuscript Summary: Interactions between bacterial hosts and their viruses (phages) lead to reciprocal genome evolution through a dynamic co-evolutionary process1-5. Phage-mediated transfer of host genes – often located in genome islands – has had a major impact on microbial evolution1, 4, 6. Furthermore, phage genomes have clearly been shaped by the acquisition of genes from their hosts2, 3, 5. Here we investigate whole-genome expression of a host and phage, the marine cyanobacterium Prochlorococcus and a T7-like cyanophage during lytic infection, to gain insight into these co-evolutionary processes. While most of the phage genome was linearly transcribed over the course of infection, 4 phage-encoded bacterial metabolism genes were part of the same expression cluster, even though they are physically separated on the genome. These genes — encoding photosystem II D1 (psbA), high-light inducible protein (hli), transaldolase (talC) and ribonucleotide reductase (nrd) — are transcribed together with phage DNA replication genes and appear to make up a functional unit involved in energy and deoxynucleotide production needed for phage replication in resource-poor oceans. Also unique to this system was the upregulation of numerous genes in the host during infection. These may be host stress response genes, and/or genes induced by the phage. Many of these host genes are located in genome islands and have homologues in cyanophage genomes. We hypothesize that phage have evolved to utilize upregulated host genes, leading to their stable incorporation into phage genomes and their subsequent transfer back to hosts in genome islands. Thus activation of host genes during infection may be directing the co-evolution of gene content in both host and phage genomes. Keywords: time course, viral infection, marine cyanobacteria, podovirus, bacteriophage, stress response
Project description:Viral infection leads to heterogeneous cellular outcomes ranging from resistance to virion amplification and cell death. In this study, we apply single-cell techniques to analyze diverse fate trajectories during Epstein-Barr virus (EBV) lytic reactivation in three B cell models. We expand upon the previous finding that c-Myc regulates lytic reactivation and determine that MYC downregulation during the lytic phase is correlated with a loss of germinal center (GC) B cell expression signatures. Consistent with prior work, lytic induction yields both abortive and complete reactivation. Abortive lytic cells, which express high STAT3 and initiate but do not complete the lytic cycle, also upregulate NF-kB and IRF3 pathway target genes. Cells that proceeded through the full lytic cycle exhibited unexpected and striking expression of genes associated with cellular reprogramming, developmental progenitor phenotypes, and cytokine upregulation. Distinct subpopulations of lytic cells further displayed variable profiles for transcripts known to escape virus-mediated host shutoff. These data reveal previously unknown and promiscuous outcomes of lytic reactivation with broad implications for viral replication and EBV-associated oncogenesis.
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.
Project description:Ebola virus (EBOV) causes epidemics with high mortality, yet remains understudied due to the challenge of experimentation in high-containment and outbreak settings. Here, we used single-cell transcriptomics and CyTOF-based single-cell protein quantification to characterize peripheral immune cells during EBOV infection in rhesus monkeys. We obtained 100,000 transcriptomes and 15,000,000 protein profiles, providing insight into pathogenesis: e.g., immature, proliferative monocyte-lineage cells with reduced antigen presentation capacity replace conventional monocyte subsets, while lymphocytes upregulate apoptosis genes and decline in abundance. By quantifying intracellular viral RNA, we identify molecular determinants of tropism among circulating immune cells and examine temporal dynamics in viral and host gene expression. Within infected cells, EBOV down-regulates STAT1 mRNA and interferon signaling, and up-regulates putative pro-viral genes (e.g., DYNLL1 and HSPA5), nominating pathways the virus manipulates for its replication. This study sheds light on EBOV tropism, replication dynamics, and elicited immune response, and provides a framework for characterizing host-virus interactions under maximum containment.
Project description:Ebola virus (EBOV) causes epidemics with high mortality, yet remains understudied due to the challenge of experimentation in high-containment and outbreak settings. Here, we used single-cell transcriptomics and CyTOF-based single-cell protein quantification to characterize peripheral immune cells during EBOV infection in rhesus monkeys. We obtained 100,000 transcriptomes and 15,000,000 protein profiles, providing insight into pathogenesis: e.g., immature, proliferative monocyte-lineage cells with reduced antigen presentation capacity replace conventional monocyte subsets, while lymphocytes upregulate apoptosis genes and decline in abundance. By quantifying intracellular viral RNA, we identify molecular determinants of tropism among circulating immune cells and examine temporal dynamics in viral and host gene expression. Within infected cells, EBOV down-regulates STAT1 mRNA and interferon signaling, and up-regulates putative pro-viral genes (e.g., DYNLL1 and HSPA5), nominating pathways the virus manipulates for its replication. This study sheds light on EBOV tropism, replication dynamics, and elicited immune response, and provides a framework for characterizing host-virus interactions under maximum containment.
Project description:Ebola virus (EBOV) causes epidemics with high mortality, yet remains understudied due to the challenge of experimentation in high-containment and outbreak settings. Here, we used single-cell transcriptomics and CyTOF-based single-cell protein quantification to characterize peripheral immune cells during EBOV infection in rhesus monkeys. We obtained 100,000 transcriptomes and 15,000,000 protein profiles, providing insight into pathogenesis: e.g., immature, proliferative monocyte-lineage cells with reduced antigen presentation capacity replace conventional monocyte subsets, while lymphocytes upregulate apoptosis genes and decline in abundance. By quantifying intracellular viral RNA, we identify molecular determinants of tropism among circulating immune cells and examine temporal dynamics in viral and host gene expression. Within infected cells, EBOV down-regulates STAT1 mRNA and interferon signaling, and up-regulates putative pro-viral genes (e.g., DYNLL1 and HSPA5), nominating pathways the virus manipulates for its replication. This study sheds light on EBOV tropism, replication dynamics, and elicited immune response, and provides a framework for characterizing host-virus interactions under maximum containment.
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.