Novel Circular Single-Stranded DNA Viruses among an Asteroid, Echinoid and Holothurian (Phylum: Echinodermata).
ABSTRACT: Echinoderms are prone to large population fluctuations that can be mediated by pervasive disease events. For the majority of echinoderm disease events the causative pathogen is unknown. Viruses have only recently been explored as potential pathogens using culture-independent techniques though little information currently exists on echinoderm viruses. In this study, ten circular ssDNA viruses were discovered in tissues among an asteroid (Asterias forbesi), an echinoid (Strongylocentrotus droebachiensis) and a holothurian (Parastichopus californicus) using viral metagenomics. Genome architecture and sequence similarity place these viruses among the rapidly expanding circular rep-encoding single stranded (CRESS) DNA viral group. Multiple genomes from the same tissue were no more similar in sequence identity to each other than when compared to other known CRESS DNA viruses. The results from this study are the first to describe a virus from a holothurian and continue to show the ubiquity of these viruses among aquatic invertebrates.
Project description:Circoviruses, cycloviruses and other circular, replication-associated protein-encoding single stranded (CRESS) DNA viruses have been detected in a variety of animal taxa. In this study, cloacal swab samples (n?=?90) were examined for CRESS DNA viruses from 31 wild bird species living at various aquatic sites in Hungary to identify possible reservoirs of viruses pathogenic to domestic poultry. A total of 30 (33.3%) specimens tested positive with pan-CRESS DNA virus specific PCR. Goose circovirus (GoCV), Duck associated cyclovirus 1 (DuACyV-1) and Garrulus glandarius associated circular virus 1 (GgaCV-1) were detected in nine, three and two different bird species, respectively. Selected specimens were subjected to whole genome sequencing. The obtained sequence data revealed conserved gene structure within the identified virus species and detected homologous (within GoCV) and possible heterologous recombination (within DuACyV-1) events. Results presented here provide new information on the genomic diversity and evolution of selected CRESS DNA viruses.
Project description:Viral metagenomics has recently revealed the ubiquitous and diverse nature of single-stranded DNA (ssDNA) viruses that encode a conserved replication initiator protein (Rep) in the marine environment. Although eukaryotic circular Rep-encoding ssDNA (CRESS-DNA) viruses were originally thought to only infect plants and vertebrates, recent studies have identified these viruses in a number of invertebrates. To further explore CRESS-DNA viruses in the marine environment, this study surveyed CRESS-DNA viruses in various marine invertebrate species. A total of 27 novel CRESS-DNA genomes, with Reps that share less than 60.1% identity with previously reported viruses, were recovered from 21 invertebrate species, mainly crustaceans. Phylogenetic analysis based on the Rep revealed a novel clade of CRESS-DNA viruses that included approximately one third of the marine invertebrate associated viruses identified here and whose members may represent a novel family. Investigation of putative capsid proteins (Cap) encoded within the eukaryotic CRESS-DNA viral genomes from this study and those in GenBank demonstrated conserved patterns of predicted intrinsically disordered regions (IDRs), which can be used to complement similarity-based searches to identify divergent structural proteins within novel genomes. Overall, this study expands our knowledge of CRESS-DNA viruses associated with invertebrates and explores a new tool to evaluate divergent structural proteins encoded by these viruses.
Project description:Numerous metagenomic studies have uncovered a remarkable diversity of circular replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA viruses, the majority of which are uncultured and unclassified. Unlike capsid proteins, the Reps show significant similarity across different groups of CRESS DNA viruses and have conserved domain organization with the N-terminal nuclease and the C-terminal helicase domain. Consequently, Rep is widely used as a marker for identification, classification and assessment of the diversity of CRESS DNA viruses. However, it has been shown that in certain viruses the Rep nuclease and helicase domains display incongruent evolutionary histories. Here, we systematically evaluated the co-evolutionary patterns of the two Rep domains across classified and unclassified CRESS DNA viruses. Our analysis indicates that the Reps encoded by members of the families Bacilladnaviridae, Circoviridae, Geminiviridae, Genomoviridae, Nanoviridae and Smacoviridae display largely congruent evolutionary patterns in the two domains. By contrast, among the unclassified CRESS DNA viruses, 71% appear to have chimeric Reps. Such massive chimerism suggests that unclassified CRESS DNA viruses represent a dynamic population in which exchange of gene fragments encoding the nuclease and helicase domains is extremely common. Furthermore, purging of the chimeric sequences uncovered six monophyletic Rep groups that may represent new families of CRESS DNA viruses.
Project description:Here, we present the complete genome sequences of three circular replication-associated protein (Rep)-encoding single-stranded DNA (CRESS DNA) viruses detected in secondary treated and disinfected wastewater effluent. The discovered viruses, named wastewater CRESS DNA virus (WCDV)-1 to -3, represent novel viral species that seem to persist in wastewater effluent.
Project description:Metagenomic analysis of diarrhea samples revealed the presence of numerous human enteric viruses and small circular Rep-encoding single-stranded DNA (CRESS-DNA) genomes. One such genome was related to smacoviruses, while eight others were related to genomes reported in the feces of different mammals. The tropism of these CRESS-DNA viruses remains unknown.
Project description:Single-stranded (ss) DNA viruses are a major component of the earth virome. In particular, the circular, Rep-encoding ssDNA (CRESS-DNA) viruses show high diversity and abundance in various habitats. By combining sequence similarity network and phylogenetic analyses of the replication proteins (Rep) belonging to the HUH endonuclease superfamily, we show that the replication machinery of the CRESS-DNA viruses evolved, on three independent occasions, from the Reps of bacterial rolling circle-replicating plasmids. The CRESS-DNA viruses emerged via recombination between such plasmids and cDNA copies of capsid genes of eukaryotic positive-sense RNA viruses. Similarly, the rep genes of prokaryotic DNA viruses appear to have evolved from HUH endonuclease genes of various bacterial and archaeal plasmids. Our findings also suggest that eukaryotic polyomaviruses and papillomaviruses with dsDNA genomes have evolved via parvoviruses from CRESS-DNA viruses. Collectively, our results shed light on the complex evolutionary history of a major class of viruses revealing its polyphyletic origins.
Project description:Replication-associated protein (Rep)-encoding single-stranded DNA (CRESS DNA) viruses are a diverse group of viruses, and their persistence in the environment has been studied for over a decade. However, the persistence of CRESS DNA viruses in herds of domestic animals has, in some cases, serious economic consequence. In this study, we describe the diversity of CRESS DNA viruses identified during the metagenomics analysis of fecal samples collected from a single swine herd with apparently healthy animals. A total of nine genome sequences were assembled and classified into two different groups (CRESSV1 and CRESSV2) of the <i>Cirlivirales</i> order (<i>Cressdnaviricota</i> phylum). The novel CRESS DNA viral sequences shared 85.8-96.8% and 38.1-94.3% amino acid sequence identities for the Rep and putative capsid protein sequences compared to their respective counterparts with extant GenBank record. Data presented here show evidence for simultaneous infection of swine herds with multiple novel CRESS DNA viruses, including po-circo-like viruses and fur seal feces-associated circular DNA viruses. Given that viral genomes with similar sequence and structure have been detected in swine fecal viromes from independent studies, investigation of the association between presence of CRESS DNA viruses and swine health conditions seems to be justified.
Project description:Metagenomic approaches are rapidly expanding our knowledge of the diversity of viruses. In the fecal matter of Nigerian chimpanzees we recovered three gokushovirus genomes, one circular replication-associated protein encoding single-stranded DNA virus (CRESS), and a CRESS DNA molecule.
Project description:Viruses encoding a replication-associated protein (Rep) within a covalently closed, single-stranded (ss)DNA genome are among the smallest viruses known to infect eukaryotic organisms, including economically valuable agricultural crops and livestock. Although circular Rep-encoding ssDNA (CRESS DNA) viruses are a widespread group for which our knowledge is rapidly expanding, biased sampling toward vertebrates and land plants has limited our understanding of their diversity and evolution. Here, we screened terrestrial arthropods for CRESS DNA viruses and report the identification of 44 viral genomes and replicons associated with specimens representing all three major terrestrial arthropod lineages, namely Euchelicerata (spiders), Hexapoda (insects), and Myriapoda (millipedes). We identified virus genomes belonging to three established CRESS DNA viral families (<i>Circoviridae</i>, <i>Genomoviridae</i>, and <i>Smacoviridae</i>); however, over half of the arthropod-associated viral genomes are only distantly related to currently classified CRESS DNA viral sequences. Although members of viral and satellite families known to infect plants (<i>Geminiviridae</i>, <i>Nanoviridae</i>, <i>Alphasatellitidae</i>) were not identified in this study, these plant-infecting CRESS DNA viruses and replicons are transmitted by hemipterans. Therefore, members from six out of the seven established CRESS DNA viral families circulate among arthropods. Furthermore, a phylogenetic analysis of Reps, including endogenous viral sequences, reported to date from a wide array of organisms revealed that most of the known CRESS DNA viral diversity circulates among invertebrates. Our results highlight the vast and unexplored diversity of CRESS DNA viruses among invertebrates and parallel findings from RNA viral discovery efforts in undersampled taxa.
Project description:The Smacoviridae has recently been classified as a family of small circular single-stranded DNA viruses. An increasing number of smacovirus genomes have been identified exclusively in faecal matter of various vertebrate species and from insect body parts. However, the genetic diversity and host range of smacoviruses remains to be fully elucidated. Herein, we report the genetic characterization of eleven circular replication-associated protein (Rep) encoding single-stranded (CRESS) DNA viruses detected in the faeces of Zambian non-human primates. Based on pairwise genome-wide and amino acid identities with reference smacovirus species, ten of the identified CRESS DNA viruses are assigned to the genera Porprismacovirus and Huchismacovirus of the family Smacoviridae, which bidirectionally encode two major open reading frames (ORFs): Rep and capsid protein (CP) characteristic of a type IV genome organization. The remaining unclassified CRESS DNA virus was related to smacoviruses but possessed a genome harbouring a unidirectionally oriented CP and Rep, assigned as a type V genome organization. Moreover, phylogenetic and recombination analyses provided evidence for recombination events encompassing the 3'-end of the Rep ORF in the unclassified CRESS DNA virus. Our findings increase the knowledge of the known genetic diversity of smacoviruses and highlight African non-human primates as carrier animals.