Project description:The flavivirids (family Flaviviridae) are a group of positive-sense RNA viruses that include well-documented agents of human disease. Despite their importance and ubiquity, the timescale of flavivirid evolution is uncertain. An ancient origin, spanning millions of years, is supported by their presence in both vertebrates and invertebrates and by the identification of a flavivirus-derived endogenous viral element in the peach blossom jellyfish genome (Craspedacusta sowerbii, phylum Cnidaria), implying that the flaviviruses arose early in the evolution of the Metazoa. To date, however, no exogenous flavivirid sequences have been identified in these hosts. To help resolve the antiquity of the Flaviviridae, we mined publicly available transcriptome data across the Metazoa. From this, we expanded the diversity within the family through the identification of 32 novel viral sequences and extended the host range of the pestiviruses to include amphibians, reptiles, and ray-finned fish. Through co-phylogenetic analysis we found cross-species transmission to be the predominate macroevolutionary event across the non-vectored flavivirid genera (median, 68 per cent), including a cross-species transmission event between bats and rodents, although long-term virus-host co-divergence was still a regular occurrence (median, 23 per cent). Notably, we discovered flavivirus-like sequences in basal metazoan species, including the first associated with Cnidaria. This sequence formed a basal lineage to the genus Flavivirus and was closer to arthropod and crustacean flaviviruses than those in the tamanavirus group, which includes a variety of invertebrate and vertebrate viruses. Combined, these data attest to an ancient origin of the flaviviruses, likely close to the emergence of the metazoans 750-800 million years ago.
Project description:Evolutionarily successful poxviruses presented effective and diverse strategies to circumvent or overcome host defense mechanisms. Poxviruses encode many immunoregulatory proteins to evade host immunity for a productive infection and unique means of inhibiting DNA-sensing dependent type 1 interferon (IFN-I) responses is anticipated due to the biology of its dsDNA genome in nature and an exclusive cytoplasmic life cycle. We found the key DNA sensing inhibition by poxvirus infection was dominant during the early stage of poxvirus infection independent from DNA replication. In an effort of identifying poxvirus novel means to subdue antiviral proinflammatory responses e.g., IFN-I response, we focused on the function of one early gene that is the known host range determinant from the highly conserved poxvirus host range C7L superfamily, myxoma virus (MYXV) M062. Host range factors are unique features of poxviruses that determine the species and cell type tropism. Almost all sequenced mammalian poxviruses retain at least one homologue of the poxvirus host range C7L superfamily. In MYXV, a rabbit specific poxvirus, the dominant and broad-spectrum host range determinant of the C7L superfamily is the M062R gene. M062R gene product is essential for MYXV infection in almost all cells tested from different mammalian species and specifically inhibits the function of host Sterile α Motif Domain-containing 9 (SAMD9), as M062R-null (ΔM062R) MYXV causes abortive infection in a SAMD9-dependend manner. In this study we investigated the immunostimulatory property of the ΔM062R. We found that the replication-defective ΔM062R infection activated host DNA sensing pathway in the cGAS dependent fashion and knocking down SAMD9 expression attenuated proinflammatory responses. Moreover, transcriptomic analyses showed a unique feature of host gene expression landscape that is different from dsDNA stimulated inflammatory state. This study built a link between the anti-neoplastic SAMD9 and the regulation of the innate immune responses.
Project description:The success of plant pathogenic fungi mostly relies on their arsenal of virulence factors that are expressed and delivered into the host tissue during colonization. The biotrophic fungal pathogen Ustilago hordei causes covered smut disease on both barley and oat. The biotrophic interaction of the fungus with its host plant starts with formation of appressorium and subsequent penetration of invasive hyphae into the plant cell, in which the plasma membrane of the infected cell gets invaginated and encases the penetrating hypha. After penetration, the fungus grows towards and in later stages along the vascular bundles, which contain assimilates and metabolites, representing a source of nutrients for the fungus. In this study, we combined cytological, genomics and molecular biological methods to achieve a better understanding of the molecular interactions in the U. hordei-barley pathosystem. This study focuses on the genome-wide Agilent Microarray-based transcriptome analysis of U. hordei during early stages (20 hpi, 40 hpi, 3 dpi, 6 dpi) of the biotrophic interaction in comparison to axenic culture growth. This should give insights into the molecular processes during these stages by the identification of regulated genes. Furthermore, the regulation of putative secreted enzymes and effector proteins can be studied. Transcriptome analysis of U. hordei at different stages of host infection revealed 273 effector gene candidates with differentially expressed transcript levels. Furthermore, U. hordei transcriptionally activates core-effector genes that may suppress even non-host early defense responses. It could be shown that about one half of the U. hordei open reading frames are differentially regulated during at least one of the analyzed stages. Based on the transcriptome data, some of them were identified to be involved in stage-specific processes, e.g. in the nutrient acquisition by the induction of carbohydrate transporters during the later stages of infection. Furthermore, a set of strongly induced genes was identified, which encode for secreted proteins. The acquired datasets show a strong induction of stage-specific secreted effector proteins, whose functions remain unclear. Based on the expression values, a group of 16 promising candidates was chosen for functional characterization. The success of plant pathogenic fungi mostly relies on their arsenal of virulence factors that are expressed and delivered into the host tissue during colonization. The biotrophic fungal pathogen Ustilago hordei causes covered smut disease on both barley and oat. The biotrophic interaction of the fungus with its host plant starts with formation of appressorium and subsequent penetration of invasive hyphae into the plant cell, in which the plasma membrane of the infected cell gets invaginated and encases the penetrating hypha. After penetration, the fungus grows towards and in later stages along the vascular bundles, which contain assimilates and metabolites, representing a source of nutrients for the fungus. In this study, we combined cytological, genomics and molecular biological methods to achieve a better understanding of the molecular interactions in the U. hordei-barley pathosystem. This study focuses on the genome-wide Agilent Microarray-based transcriptome analysis of U. hordei during early stages (20 hpi, 40 hpi, 3 dpi, 6 dpi) of the biotrophic interaction in comparison to axenic culture growth. This should give insights into the molecular processes during these stages by the identification of regulated genes. Furthermore, the regulation of putative secreted enzymes and effector proteins can be studied. Transcriptome analysis of U. hordei at different stages of host infection revealed 273 effector gene candidates with differentially expressed transcript levels. Furthermore, U. hordei transcriptionally activates core-effector genes that may suppress even non-host early defense responses. It could be shown that about one half of the U. hordei open reading frames are differentially regulated during at least one of the analyzed stages. Based on the transcriptome data, some of them were identified to be involved in stage-specific processes, e.g. in the nutrient acquisition by the induction of carbohydrate transporters during the later stages of infection. Furthermore, a set of strongly induced genes was identified, which encode for secreted proteins.The acquired datasets show a strong induction of stage-specific secreted effector proteins, whose functions remain unclear. Based on the expression values, a group of 16 promising candidates was chosen for functional characterization.