scholarly journals A new lineage of segmented RNA viruses infecting animals

2019 ◽  
Author(s):  
Darren J. Obbard ◽  
Mang Shi ◽  
Katherine E. Roberts ◽  
Ben Longdon ◽  
Alice B. Dennis
Keyword(s):  
Small Rnas ◽  
Rna Viruses ◽  
Rna Virus ◽  
Close Relative ◽  
Metagenomic Sequencing ◽  
Reading Frame ◽  
Virus Identification ◽  
Conserved Sequence ◽  
Virus Diversity ◽  
Close Relatives

AbstractMetagenomic sequencing has revolutionised our knowledge of virus diversity, with new virus sequences being reported faster than ever before. However, virus discovery from metagenomic sequencing usually depends on detectable homology: without a sufficiently close relative, so-called ‘dark’ virus sequences remain unrecognisable. An alternative approach is to use virus-identification methods that do not depend on detecting homology, such as virus recognition by host antiviral immunity. For example, virus-derived small RNAs have previously been used to propose ‘dark’ virus sequences associated with the Drosophilidae (Diptera). Here we combine published Drosophila data with a comprehensive search of transcriptomic sequences and selected meta-transcriptomic datasets to identify a completely new lineage of segmented positive-sense single-stranded RNA viruses that we provisionally refer to as the Quenyaviruses. Each of the five segments contains a single open reading frame, with most encoding proteins showing no detectable similarity to characterised viruses, and one sharing a small number of residues with the RNA-dependent RNA polymerases of single- and double-stranded RNA viruses. Using these sequences, we identify close relatives in approximately 20 arthropods, including insects, crustaceans, spiders and a myriapod. Using a more conserved sequence from the putative polymerase, we further identify relatives in meta-transcriptomic datasets from gut, gill, and lung tissues of vertebrates, reflecting infections of vertebrates or of their associated parasites. Our data illustrate the utility of small RNAs to detect viruses with limited sequence conservation, and provide robust evidence for a new deeply divergent and phylogenetically distinct RNA virus lineage.

scholarly journals A new lineage of segmented RNA viruses infecting animals

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Darren J Obbard ◽  
Mang Shi ◽  
Katherine E Roberts ◽  
Ben Longdon ◽  
Alice B Dennis
Keyword(s):  
Small Rnas ◽  
Rna Viruses ◽  
Rna Virus ◽  
Close Relative ◽  
Metagenomic Sequencing ◽  
Reading Frame ◽  
Virus Identification ◽  
Conserved Sequence ◽  
Virus Diversity ◽  
Close Relatives

Abstract Metagenomic sequencing has revolutionised our knowledge of virus diversity, with new virus sequences being reported faster than ever before. However, virus discovery from metagenomic sequencing usually depends on detectable homology: without a sufficiently close relative, so-called ‘dark’ virus sequences remain unrecognisable. An alternative approach is to use virus-identification methods that do not depend on detecting homology, such as virus recognition by host antiviral immunity. For example, virus-derived small RNAs have previously been used to propose ‘dark’ virus sequences associated with the Drosophilidae (Diptera). Here, we combine published Drosophila data with a comprehensive search of transcriptomic sequences and selected meta-transcriptomic datasets to identify a completely new lineage of segmented positive-sense single-stranded RNA viruses that we provisionally refer to as the Quenyaviruses. Each of the five segments contains a single open reading frame, with most encoding proteins showing no detectable similarity to characterised viruses, and one sharing a small number of residues with the RNA-dependent RNA polymerases of single- and double-stranded RNA viruses. Using these sequences, we identify close relatives in approximately 20 arthropods, including insects, crustaceans, spiders, and a myriapod. Using a more conserved sequence from the putative polymerase, we further identify relatives in meta-transcriptomic datasets from gut, gill, and lung tissues of vertebrates, reflecting infections of vertebrates or of their associated parasites. Our data illustrate the utility of small RNAs to detect viruses with limited sequence conservation, and provide robust evidence for a new deeply divergent and phylogenetically distinct RNA virus lineage.

scholarly journals Marine RNA Virus Quasispecies Are Distributed throughout the Oceans

mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Marli Vlok ◽  
Andrew S. Lang ◽  
Curtis A. Suttle
Keyword(s):  
Amino Acid ◽  
Rna Viruses ◽  
Rna Virus ◽  
Purifying Selection ◽  
Amino Acid Sequences ◽  
Metagenomic Data ◽  
Spatial And Temporal Patterns ◽  
Data Set ◽  
Virus Diversity ◽  
Virus Genomes

ABSTRACTRNA viruses, particularly genetically diverse members of thePicornavirales, are widespread and abundant in the ocean. Gene surveys suggest that there are spatial and temporal patterns in the composition of RNA virus assemblages, but data on their diversity and genetic variability in different oceanographic settings are limited. Here, we show that specific RNA virus genomes have widespread geographic distributions and that the dominant genotypes are under purifying selection. Genomes from three previously unknown picorna-like viruses (BC-1, -2, and -3) assembled from a coastal site in British Columbia, Canada, as well as marine RNA viruses JP-A, JP-B, andHeterosigma akashiwoRNA virus exhibited different biogeographical patterns. Thus, biotic factors such as host specificity and viral life cycle, and not just abiotic processes such as dispersal, affect marine RNA virus distribution. Sequence differences relative to reference genomes imply that virus quasispecies are under purifying selection, with synonymous single-nucleotide variations dominating in genomes from geographically distinct regions resulting in conservation of amino acid sequences. Conversely, sequences from coastal South Africa that mapped to marine RNA virus JP-A exhibited more nonsynonymous mutations, probably representing amino acid changes that accumulated over a longer separation. This biogeographical analysis of marine RNA viruses demonstrates that purifying selection is occurring across oceanographic provinces. These data add to the spectrum of known marine RNA virus genomes, show the importance of dispersal and purifying selection for these viruses, and indicate that closely related RNA viruses are pathogens of eukaryotic microbes across oceans.IMPORTANCEVery little is known about aquatic RNA virus populations and genome evolution. This is the first study that analyzes marine environmental RNA viral assemblages in an evolutionary and broad geographical context. This study contributes the largest marine RNA virus metagenomic data set to date, substantially increasing the sequencing space for RNA viruses and also providing a baseline for comparisons of marine RNA virus diversity. The new viruses discovered in this study are representative of the most abundant family of marine RNA viruses, theMarnaviridae, and expand our view of the diversity of this important group. Overall, our data and analyses provide a foundation for interpreting marine RNA virus diversity and evolution.

scholarly journals Evolutionary origins of epidemic potential among human RNA viruses

2019 ◽  
Author(s):  
Lu Lu ◽  
Liam Brierley ◽  
Gail Robertson ◽  
Feifei Zhang ◽  
Samantha Lycett ◽  
...  
Keyword(s):  
Rna Viruses ◽  
Rna Virus ◽  
Virus Genome ◽  
Human Populations ◽  
Infective Virus ◽  
Genome Sequences ◽  
Evolutionary Origins ◽  
Virus Diversity ◽  
Human Viruses ◽  
Do So

AbstractTo have epidemic potential, a pathogen must be able to spread in human populations, but of human-infective RNA viruses only a minority can do so. We investigated the evolution of human transmissibility through parallel analyses of 1755 virus genome sequences from 39 RNA virus genera. We identified 57 lineages containing human-transmissible species and estimated that at least 74% of these lineages have evolved directly from non-human viruses in other mammals or birds, a public health threat recently designated “Disease X”. Human-transmissible viruses rarely evolve from virus lineages that can infect but not transmit between humans. This result cautions against focussing surveillance and mitigation efforts narrowly on currently known human-infective virus lineages and supports calls for a better understanding of RNA virus diversity in non-human hosts.

scholarly journals Viromes in Marine Ecosystems Reveal Remarkable Invertebrate RNA Virus Diversity

2021 ◽  
Author(s):  
Yu-Yi Zhang ◽  
Yicong Chen ◽  
Xiaoman Wei ◽  
Jie Cui
Keyword(s):  
Rna Viruses ◽  
Rna Virus ◽  
Marine Invertebrate ◽  
Ecological Factors ◽  
Virus Evolution ◽  
Marine Ecosystems ◽  
Invertebrate Species ◽  
Virus Diversity ◽  
First Time ◽  
Special Notice

AbstractOcean viromes remain poorly understood and little is known about the ecological factors driving aquatic RNA virus evolution. In this study, we used a meta-transcriptomic approach to characterize the viromes of 58 marine invertebrate species across three seas. This revealed the presence of 315 newly identified RNA viruses in nine viral families or orders (Durnavirales, Totiviridae, Bunyavirales, Hantaviridae, Picornavirales, Flaviviridae, Hepelivirales, Solemoviridae and Tombusviridae), with most of them are sufficiently divergent to the documented viruses. With special notice that we first time revealed an ocean virus rooting to mammalian hantaviruses. We also found evidence for possible host sharing and switch events during virus evolution. In sum, we demonstrated the hidden diversity of marine invertebrate RNA viruses.

scholarly journals A Retrospective Paired Comparison Between Untargeted Next Generation Sequencing and Conventional Microbiology Tests With Wisely Chosen Metagenomic Sequencing Positive Criteria

2021 ◽  
Vol 8 ◽  
Author(s):  
Hanyu Qin ◽  
Jinmin Peng ◽  
Ling Liu ◽  
Jing Wu ◽  
Lingai Pan ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Fungal Infections ◽  
Rna Virus ◽  
Paired Comparison ◽  
Final Analysis ◽  
Metagenomic Sequencing ◽  
Next Generation ◽  
Dna Virus ◽  
Virus Identification ◽  
Generation Sequencing

Objectives: To evaluate the performance of metagenomic next generation sequencing (mNGS) using adequate criteria for the detection of pathogens in lower respiratory tract (LRT) samples with a paired comparison to conventional microbiology tests (CMT).Methods: One hundred sixty-seven patients were reviewed from four different intensive care units (ICUs) in mainland China during 2018 with both mNGS and CMT results of LRT samples available. The reads per million ratio (RPMsample/RPMnon−template−control ratio) and standardized strictly mapped reads number (SDSMRN) were the two criteria chosen for identifying positive pathogens reported from mNGS. A McNemar test was used for a paired comparison analysis between mNGS and CMT.Results: One hundred forty-nine cases were counted into the final analysis. The RPMsample/RPMNTC ratio criterion performed better with a higher accuracy for bacteria, fungi, and virus than SDSMRN criterion [bacteria (RPMsample/RPMNTC ratio vs. SDSMRN), 65.1 vs. 55.7%; fungi, 75.8 vs. 71.1%; DNA virus, 86.3 vs. 74.5%; RNA virus, 90.9 vs. 81.8%]. The mNGS was also superior in bacteria detection only if an SDSMRN ≥3 was used as a positive criterion with a paired comparison to culture [SDSMRN positive, 92/149 (61.7%); culture positive, 54/149 (36.2%); p < 0.001]; however, it was outperformed with significantly more fungi and DNA virus identification when choosing both criteria for positive outliers [fungi (RPMsample/RPMNTC ratio vs. SDSMRN vs. culture), 23.5 vs. 29.5 vs. 8.7%, p < 0.001; DNA virus (RPMsample/RPMNTC ratio vs. SDSMRN vs. PCR), 14.1 vs. 20.8 vs. 11.8%, p < 0.05].Conclusions: Metagenomic next generation sequencing may contribute to revealing the LRT infection etiology in hospitalized groups of potential fungal infections and in situations with less access to the multiplex PCR of LRT samples from the laboratory by choosing a wise criterion like the RPMsample/RPMNTC ratio.

scholarly journals Chemogenetic ON and OFF switches for RNA virus replication

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
E. Heilmann ◽  
J. Kimpel ◽  
B. Hofer ◽  
A. Rössler ◽  
I. Blaas ◽  
...  
Keyword(s):  
Protease Inhibitor ◽  
Rna Viruses ◽  
Rna Virus ◽  
Hiv Protease ◽  
Hiv Protease Inhibitors ◽  
Dependent Manner ◽  
Reading Frame ◽  
Virus Activity ◽  
Gene Vectors ◽  
Or Gene

AbstractTherapeutic application of RNA viruses as oncolytic agents or gene vectors requires a tight control of virus activity if toxicity is a concern. Here we present a regulator switch for RNA viruses using a conditional protease approach, in which the function of at least one viral protein essential for transcription and replication is linked to autocatalytical, exogenous human immunodeficiency virus (HIV) protease activity. Virus activity can be en- or disabled by various HIV protease inhibitors. Incorporating the HIV protease dimer in the genome of vesicular stomatitis virus (VSV) into the open reading frame of either the P- or L-protein resulted in an ON switch. Here, virus activity depends on co-application of protease inhibitor in a dose-dependent manner. Conversely, an N-terminal VSV polymerase tag with the HIV protease dimer constitutes an OFF switch, as application of protease inhibitor stops virus activity. This technology may also be applicable to other potentially therapeutic RNA viruses.

scholarly journals Application of a sequence-based taxonomic classification method to uncultured and unclassified marine single-stranded RNA viruses in the order Picornavirales

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Marli Vlok ◽  
Andrew S Lang ◽  
Curtis A Suttle
Keyword(s):  
Rna Viruses ◽  
Sequence Data ◽  
Rna Virus ◽  
Taxonomic Classification ◽  
Sound Classification ◽  
Virus Diversity ◽  
Species Demarcation Threshold ◽  
The Family ◽  
Genetic Features ◽  
Taxonomic Framework

Abstract Metagenomics has altered our understanding of microbial diversity and ecology. This includes its applications to viruses in marine environments that have demonstrated their enormous diversity. Within these are RNA viruses, many of which share genetic features with members of the order Picornavirales; yet, very few of these have been taxonomically classified. The only recognized family of marine RNA viruses is the Marnaviridae, which was founded based on discovery and characterization of the species Heterosigma akashiwo RNA virus. Two additional genera of marine RNA viruses, Labyrnavirus (one species) and Bacillarnavirus (three species), were subsequently defined within the order Picornavirales but not assigned to a family. We have defined a sequence-based framework for taxonomic classification of twenty marine RNA viruses into the family Marnaviridae. Using RNA-dependent RNA polymerase (RdRp) phylogeny and distance-based analyses, we assigned the genera Labyrnavirus and Bacillarnavirus to the family Marnaviridae and created four additional genera in the family: Locarnavirus (four species), Kusarnavirus (one species), Salisharnavirus (four species) and Sogarnavirus (six species). We used pairwise capsid protein comparisons to delineate species within families, with 75 per cent identity as the species demarcation threshold. The family displays high sequence diversities and Jukes–Cantor distances for both the RdRp and capsid genes, suggesting that the classified viruses are not representative of all of the virus diversity within the family and that there are many more extant taxa. Our proposed taxonomic framework provides a sound classification system for this group of viruses that will have broadly applicable principles for other viral groups. It is based on sequence data alone and provides a robust taxonomic framework to include viruses discovered via metagenomic studies, thereby greatly expanding the realm of viruses subject to taxonomic classification.

scholarly journals Human and Animal RNA Virus Diversity Detected by Metagenomics in Cameroonian Clams

2021 ◽  
Vol 12 ◽  
Author(s):  
Patrice Bonny ◽  
Julien Schaeffer ◽  
Alban Besnard ◽  
Marion Desdouits ◽  
Jean Justin Essia Ngang ◽  
...  
Keyword(s):  
De Novo ◽  
Hepatitis A Virus ◽  
Rna Viruses ◽  
Rna Virus ◽  
Zoonotic Transmission ◽  
Taxonomic Assignment ◽  
Virus Diversity ◽  
Health Authorities ◽  
Viral Contaminants ◽  
Quality Filtering

Many recent pandemics have been recognized as zoonotic viral diseases. While their origins remain frequently unknown, environmental contamination may play an important role in emergence. Thus, being able to describe the viral diversity in environmental samples contributes to understand the key issues in zoonotic transmission. This work describes the use of a metagenomic approach to assess the diversity of eukaryotic RNA viruses in river clams and identify sequences from human or potentially zoonotic viruses. Clam samples collected over 2years were first screened for the presence of norovirus to verify human contamination. Selected samples were analyzed using metagenomics, including a capture of sequences from viral families infecting vertebrates (VirCapSeq-VERT) before Illumina NovaSeq sequencing. The bioinformatics analysis included pooling of data from triplicates, quality filtering, elimination of bacterial and host sequences, and a deduplication step before de novo assembly. After taxonomic assignment, the viral fraction represented 0.8–15% of reads with most sequences (68–87%) remaining un-assigned. Yet, several mammalian RNA viruses were identified. Contigs identified as belonging to the Astroviridae were the most abundant, with some nearly complete genomes of bastrovirus identified. Picobirnaviridae sequences were related to strains infecting bats, and few others to strains infecting humans or other hosts. Hepeviridae sequences were mostly related to strains detected in sponge samples but also strains from swine samples. For Caliciviridae and Picornaviridae, most of identified sequences were related to strains infecting bats, with few sequences close to human norovirus, picornavirus, and genogroup V hepatitis A virus. Despite a need to improve the sensitivity of our method, this study describes a large diversity of RNA virus sequences from clam samples. To describe all viral contaminants in this type of food, and being able to identify the host infected by viral sequences detected, may help to understand some zoonotic transmission events and alert health authorities of possible emergence.

scholarly journals Meta-transcriptomic comparison of the RNA viromes of the mosquito vectors Culex pipiens and Culex torrentium in northern Europe

2019 ◽  
Author(s):  
John H.-O. Pettersson ◽  
Mang Shi ◽  
John-Sebastian Eden ◽  
Edward C. Holmes ◽  
Jenny C. Hesson
Keyword(s):  
Culex Pipiens ◽  
Rna Viruses ◽  
Rna Virus ◽  
Mosquito Species ◽  
Animal Health ◽  
Northern Europe ◽  
Mosquito Vector ◽  
Tropical Regions ◽  
South Central ◽  
Virus Diversity

AbstractThere is mounting evidence that mosquitoes harbour an extensive diversity of ‘insect-specific’ RNA viruses in addition to those important to human and animal health. However, because most studies of the mosquito virome have been conducted at lower latitudes there is a major knowledge gap on the genetic diversity, evolutionary history, and spread of RNA viruses sampled from mosquitoes in northern latitudes. Here, we determined and compared the RNA virome of two common northern Culex mosquito species, Cx. pipiens and Cx. torrentium, known vectors of West Nile virus and Sindbis virus, respectively, collected in south-central Sweden. Following bulk RNA-sequencing (meta-transcriptomics) of 12 libraries, comprising 120 specimens of Cx. pipiens and 150 specimens of Cx. torrentium, we identified 40 viruses (representing 14 virus families) of which 28 were novel based on phylogenetic analysis of the RNA-dependent RNA polymerase (RdRp) protein. Hence, we found similar levels of virome diversity as in mosquitoes sampled from the more biodiverse lower latitudes. Four libraries, all from Cx. torrentium, had a significantly higher abundance of viral reads, spanning ∼7– 36% of the total amount of reads. Many of these viruses were also related to those sampled on other continents, indicative of widespread global movement and/or long host-virus co-evolution. Importantly, although the two mosquito species investigated have overlapping geographical distributions and share many viruses, approximately one quarter of the viruses were only found at a specific location, such that geography must play an important role in shaping the diversity of RNA viruses in Culex mosquitoes.ImportanceRNA viruses are found in all domains of life and all global habitats. However, the factors that determine virome composition and structure within and between organisms are largely unknown. Herein, we characterised RNA virus diversity in two common mosquito vector species, Culex pipiens and Culex torrentium, sampled from northern Europe. Our analysis revealed extensive viral diversity, including 28 novel viruses, and was comparable to the levels of diversity found in other temperate and tropical regions globally. Importantly, as well as harbouring RNA viruses that are closely related to other mosquito-derived viruses sampled in diverse global locations, we also described a number of viruses that are unique to specific sampling locations in Sweden. Hence, these data showed that geographical factors can play an important role in shaping virome structure even at local scales.

scholarly journals A planarian nidovirus expands the limits of RNA genome size

2018 ◽  
Author(s):  
Amir Saberi ◽  
Anastasia A. Gulyaeva ◽  
John L. Brubacher ◽  
Phillip A. Newmark ◽  
Alexander E. Gorbalenya
Keyword(s):  
Genome Size ◽  
Secretory Cell ◽  
Rna Viruses ◽  
Rna Virus ◽  
Evolutionary Analysis ◽  
Reading Frame ◽  
Autonomous Replication ◽  
Rna Genome ◽  
On The Road ◽  
Cellular Dna

AbstractRNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication (albeit within a permissive environment). A 33.5-kb nidovirus has been considered close to the upper size limit for such entities; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the transition from primordial RNP to contemporary DNA-RNP-based life. Whether or not RNA viruses represent transitional steps on the road to DNA-based life, studies of larger RNA viruses advance our understanding of size constraints on RNP entities. For example, emergence of the largest previously known RNA genomes (20-34 kb in positive-stranded nidoviruses, including coronaviruses) is associated with a proofreading exoribonuclease encoded in the nidoviral open reading frame 1b (ORF1b). However, apparent constraints on the size of ORF1b, which encodes this and other key replicative enzymes, have been hypothesized to limit further expansion of viral RNA genomes. Here, we characterize a novel nidovirus (planarian secretory cell nidovirus; PSCNV) whose disproportionately large ORF1b-like region, and overall 41.1 kb genome, substantially extend the presumed limits on RNA genome size. This genome encodes a predicted 13,556-aa polyprotein in an unconventional single ORF, yet retains canonical nidoviral genome organization and expression, and key replicative domains. Our evolutionary analysis suggests that PSCNV diverged early from multi-ORF nidoviruses, and subsequently acquired additional genes, including those typical of large DNA viruses or hosts. PSCNV’s greatly expanded genome, proteomic complexity, and unique features – impressive in themselves – attest to the likelihood of still-larger RNA genomes awaiting discovery.Significance StatementRNA viruses are the only known RNA-protein (RNP) entities capable of autonomous replication. The upper genome size for such entities was assumed to be <35 kb; conversely, the minimal cellular DNA genome is ~200 kb. This large difference presents a daunting gap for the proposed evolution of contemporary DNA-RNP-based life from primordial RNP entities. Here, we describe a nidovirus from planarians, whose 41.1 kb genome is 23% larger than the largest known of RNA virus. The planarian secretory cell nidovirus has broken apparent constraints on the size of the genomic subregion that encodes core replication machinery, and has acquired genes not previously observed in RNA viruses. This virus challenges and advances our understanding of the limits to RNA genome size.

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