Project description:Cyanobacteria are highly abundant in the oceans and are constantly exposed to lytic viruses. The T4-like cyanomyoviruses are abundant in the marine environment and have broad host ranges relative to other cyanophages. It is currently unknown whether broad-host-range phages specifically tailor their infection program for each host, or employ the same program irrespective of the host infected. Also unknown is how different hosts respond to infection by the same phage. Here we used microarray and RNA-seq analyses to investigate the interaction between the Syn9 T4-like cyanophage and three phylogenetically, ecologically and genomically distinct marine Synechococcus strains: WH8102, WH7803 and WH8109. Strikingly, Syn9 led a nearly identical infection and transcriptional program in all three hosts. Different to previous assumptions for T4-like cyanophages, three temporally regulated gene expression classes were observed. Furthermore, a novel regulatory element controlled early gene transcription, and host-like promoters drove middle gene transcription, different to the regulatory paradigm for T4. Similar results were found for the P-TIM40 phage during infection of Prochlorococcus NATL2A. Moreover, genomic and metagenomic analyses indicate that these regulatory elements are abundant and conserved among T4-like cyanophages. In contrast to the near-identical transcriptional program employed by Syn9, host responses to infection involved host-specific genes primarily located in hypervariable genomic islands, substantiating islands as a major axis of phage-cyanobacteria interactions. Our findings suggest that the ability of broad host-range phages to infect multiple hosts is more likely dependent on the effectiveness of host defense strategies than on differential tailoring of the infection process by the phage.
Project description:Cyanobacteria are highly abundant in the oceans and are constantly exposed to lytic viruses. The T4-like cyanomyoviruses are abundant in the marine environment and have broad host ranges relative to other cyanophages. It is currently unknown whether broad-host-range phages specifically tailor their infection program for each host, or employ the same program irrespective of the host infected. Also unknown is how different hosts respond to infection by the same phage. Here we used microarray and RNA-seq analyses to investigate the interaction between the Syn9 T4-like cyanophage and three phylogenetically, ecologically and genomically distinct marine Synechococcus strains: WH8102, WH7803 and WH8109. Strikingly, Syn9 led a nearly identical infection and transcriptional program in all three hosts. Different to previous assumptions for T4-like cyanophages, three temporally regulated gene expression classes were observed. Furthermore, a novel regulatory element controlled early gene transcription, and host-like promoters drove middle gene transcription, different to the regulatory paradigm for T4. Similar results were found for the P-TIM40 phage during infection of Prochlorococcus NATL2A. Moreover, genomic and metagenomic analyses indicate that these regulatory elements are abundant and conserved among T4-like cyanophages. In contrast to the near-identical transcriptional program employed by Syn9, host responses to infection involved host-specific genes primarily located in hypervariable genomic islands, substantiating islands as a major axis of phage-cyanobacteria interactions. Our findings suggest that the ability of broad host-range phages to infect multiple hosts is more likely dependent on the effectiveness of host defense strategies than on differential tailoring of the infection process by the phage.
Project description:The worldwide spread of severe acute respiratory syndrome-related coronavirus-2 (SARS- CoV-2) caused an urgent need for an in-depth understanding of virus-host interactions. Here, we dissected the dynamics of virus replication and the host cell transcriptional response to SARS-CoV-2 infection at a systems level by combining time-resolved RNA sequencing with mathematical modeling. We observed an immediate transcriptional activation of inflammatory pathways linked to the anti-viral response followed by increased expression of genes involved in ribosome and mitochondria function, thus hinting at rapid alterations in protein production and cellular energy supply. At later stages, metabolic processes, in particular those related to xenobiotic metabolism, were downregulated. To gain a deeper understanding of the underlying transcriptional dynamics, we developed an ODE model of SARS-CoV-2 infection and replication. Mathematical modeling of SARS-CoV-2 replication suggested a strong inhibitory effect of SARS-CoV-2 proteins on the anti-viral response and a large excess of virus transcripts over the translation capacity. Our study provides insights into the sequence of SARS-CoV-2 virus-host interactions and facilitates the identification of druggable host pathways supporting virus replication.
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.
Project description:Discrimination between self vs. non-self and adequate response to infection and tissue damage are fundamental functions of the immune system. The rapid and global spread of known and emerging viruses is a testament that the timely detection of viral pathogens that reproduce within host cells, presents a formidable challenge to the immune system. To gain access to a proper reproductive niche, many pathogens travel via the host vasculature and therefore become exposed to humoral factors of the innate immune system. Although a cascade of coagulation factors plays a fundamental role in host defense for “living fossils” such as horseshoe crabs (Xiphosurida spp), the role of the coagulation system in activation of innate responses to pathogens in higher organisms remains unclear. When human type C adenovirus (HAdv) enters the circulation, 240 copies of coagulation factor X (FX) bind to the virus particle with picomolar affinity. Here, using molecular dynamics flexible fitting (MDFF) and high resolution cryo-electron microscopy (cryo-EM), we defined the interface between the HAdv5 hexon protein and FX at pseudo-atomic level. Based on this structural data, we introduced a single amino acid substitution, T424A, in the hexon that completely abrogated FX interaction with the virus. In vivo genome-wide transcriptional profiling revealed that FX-binding-ablated virus failed to activate a distinct network of the early response genes, whose expression depends on transcription factor NFKB1. Deconvolution of the signaling network responsible for early gene activation showed that the FX-HAdv complex triggers MyD88/TRIF/TRAF6 signaling upon activation of toll-like receptor 4 (TLR4) that serves as a principal sensor of FX-virus complex in vivo. Our study implicates host factor “decoration” of the virus as a mechanism to trigger innate immune sensor that respond to a misplacement of coagulation FX from the blood into intracellular macrophage compartments upon virus entry into the cell. Our results further the mounting evidence of evolutionary conservation between the coagulation system and innate immunity. Two strains of mice, C57BL/6, and Il1r1-/- deficient. Mice were challenged with wild type HAdv5 or HAdv5-based vectors.
Project description:Discrimination between self vs. non-self and adequate response to infection and tissue damage are fundamental functions of the immune system. The rapid and global spread of known and emerging viruses is a testament that the timely detection of viral pathogens that reproduce within host cells, presents a formidable challenge to the immune system. To gain access to a proper reproductive niche, many pathogens travel via the host vasculature and therefore become exposed to humoral factors of the innate immune system. Although a cascade of coagulation factors plays a fundamental role in host defense for “living fossils” such as horseshoe crabs (Xiphosurida spp), the role of the coagulation system in activation of innate responses to pathogens in higher organisms remains unclear. When human type C adenovirus (HAdv) enters the circulation, 240 copies of coagulation factor X (FX) bind to the virus particle with picomolar affinity. Here, using molecular dynamics flexible fitting (MDFF) and high resolution cryo-electron microscopy (cryo-EM), we defined the interface between the HAdv5 hexon protein and FX at pseudo-atomic level. Based on this structural data, we introduced a single amino acid substitution, T424A, in the hexon that completely abrogated FX interaction with the virus. In vivo genome-wide transcriptional profiling revealed that FX-binding-ablated virus failed to activate a distinct network of the early response genes, whose expression depends on transcription factor NFKB1. Deconvolution of the signaling network responsible for early gene activation showed that the FX-HAdv complex triggers MyD88/TRIF/TRAF6 signaling upon activation of toll-like receptor 4 (TLR4) that serves as a principal sensor of FX-virus complex in vivo. Our study implicates host factor “decoration” of the virus as a mechanism to trigger innate immune sensor that respond to a misplacement of coagulation FX from the blood into intracellular macrophage compartments upon virus entry into the cell. Our results further the mounting evidence of evolutionary conservation between the coagulation system and innate immunity.