Zoonotic risk assessment among farmed mammals.

Farmed mammals may act as hosts for zoonotic viruses that can cause disease outbreaks in humans. This SnapShot shows which farmed mammals, and to what extent, are of particular risk of harboring and spreading viruses from viral families that are commonly associated with zoonotic disease. It also discusses genome surveillance methods and biosafety measures. To view this SnapShot, open or download the PDF.

Virome characterization of game animals in China reveals a spectrum of emerging pathogens.

Game animals are wildlife species traded and consumed as food and are potential reservoirs for SARS-CoV and SARS-CoV-2. We performed a meta-transcriptomic analysis of 1,941 game animals, representing 18 species and five mammalian orders, sampled across China. From this, we identified 102 mammalian-infecting viruses, with 65 described for the first time. Twenty-one viruses were considered as potentially high risk to humans and domestic animals. Civets (Paguma larvata) carried the highest number of potentially high-risk viruses. We inferred the transmission of bat-associated coronavirus from bats to civets, as well as cross-species jumps of coronaviruses from bats to hedgehogs, from birds to porcupines, and from dogs to raccoon dogs. Of note, we identified avian Influenza A virus H9N2 in civets and Asian badgers, with the latter displaying respiratory symptoms, as well as cases of likely human-to-wildlife virus transmission. These data highlight the importance of game animals as potential drivers of disease emergence.

Using Metagenomics to Characterize an Expanding Virosphere.

We know less about viruses than any other lifeform. Fortunately, metagenomics has led to a massive expansion in the known diversity of the virosphere. Here, we discuss how metagenomics has changed our understanding of RNA viruses and present some of the remaining challenges, including characterization of the "dark matter" of divergent viral genomes.

Association of vaccination, international travel, public health and social measures with lineage dynamics of SARS-CoV-2.

Continually emerging SARS-CoV-2 variants of concern that can evade immune defenses are driving recurrent epidemic waves of COVID-19 globally. However, the impact of measures to contain the virus and their effect on lineage diversity dynamics are poorly understood. Here, we jointly analyzed international travel, public health and social measures (PHSM), COVID-19 vaccine rollout, SARS-CoV-2 lineage diversity, and the case growth rate (GR) from March 2020 to September 2022 across 63 countries. We showed that despite worldwide vaccine rollout, PHSM are effective in mitigating epidemic waves and lineage diversity. An increase of 10,000 monthly travelers in a single country-to-country route between endemic countries corresponds to a 5.5% (95% CI: 2.9 to 8.2%) rise in local lineage diversity. After accounting for PHSM, natural immunity from previous infections, and waning immunity, we discovered a negative association between the GR of cases and adjusted vaccine coverage (AVC). We also observed a complex relationship between lineage diversity and vaccine rollout. Specifically, we found a significant negative association between lineage diversity and AVC at both low and high levels but not significant at the medium level. Our study deepens the understanding of population immunity and lineage dynamics for future pandemic preparedness and responsiveness.

Spike substitution T813S increases Sarbecovirus fusogenicity by enhancing the usage of TMPRSS2.

SARS-CoV Spike (S) protein shares considerable homology with SARS-CoV-2 S, especially in the conserved S2 subunit (S2). S protein mediates coronavirus receptor binding and membrane fusion, and the latter activity can greatly influence coronavirus infection. We observed that SARS-CoV S is less effective in inducing membrane fusion compared with SARS-CoV-2 S. We identify that S813T mutation is sufficient in S2 interfering with the cleavage of SARS-CoV-2 S by TMPRSS2, reducing spike fusogenicity and pseudoparticle entry. Conversely, the mutation of T813S in SARS-CoV S increased fusion ability and viral replication. Our data suggested that residue 813 in the S was critical for the proteolytic activation, and the change from threonine to serine at 813 position might be an evolutionary feature adopted by SARS-2-related viruses. This finding deepened the understanding of Spike fusogenicity and could provide a new perspective for exploring Sarbecovirus' evolution.

VirBot: an RNA viral contig detector for metagenomic data.

SUMMARY: Without relying on cultivation, metagenomic sequencing greatly accelerated the novel RNA virus detection. However, it is not trivial to accurately identify RNA viral contigs from a mixture of species. The low content of RNA viruses in metagenomic data requires a highly specific detector, while new RNA viruses can exhibit high genetic diversity, posing a challenge for alignment-based tools. In this work, we developed VirBot, a simple yet effective RNA virus identification tool based on the protein families and the corresponding adaptive score cutoffs. We benchmarked it with seven popular tools for virus identification on both simulated and real sequencing data. VirBot shows its high specificity in metagenomic datasets and superior sensitivity in detecting novel RNA viruses. AVAILABILITY AND IMPLEMENTATION: https://github.com/GreyGuoweiChen/RNA_virus_detector. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Total infectome characterization of respiratory infections in pre-COVID-19 Wuhan, China.

At the end of 2019 Wuhan witnessed an outbreak of "atypical pneumonia" that later developed into a global pandemic. Metagenomic sequencing rapidly revealed the causative agent of this outbreak to be a novel coronavirus denoted SARS-CoV-2. To provide a snapshot of the pathogens in pneumonia-associated respiratory samples from Wuhan prior to the emergence of SARS-CoV-2, we collected bronchoalveolar lavage fluid samples from 408 patients presenting with pneumonia and acute respiratory infections at the Central Hospital of Wuhan between 2016 and 2017. Unbiased total RNA sequencing was performed to reveal their "total infectome", including viruses, bacteria and fungi. We identified 35 pathogen species, comprising 13 RNA viruses, 3 DNA viruses, 16 bacteria and 3 fungi, often at high abundance and including multiple co-infections (13.5%). SARS-CoV-2 was not present. These data depict a stable core infectome comprising common respiratory pathogens such as rhinoviruses and influenza viruses, an atypical respiratory virus (EV-D68), and a single case of a sporadic zoonotic pathogen-Chlamydia psittaci. Samples from patients experiencing respiratory disease on average had higher pathogen abundance than healthy controls. Phylogenetic analyses of individual pathogens revealed multiple origins and global transmission histories, highlighting the connectedness of the Wuhan population. This study provides a comprehensive overview of the pathogens associated with acute respiratory infections and pneumonia, which were more diverse and complex than obtained using targeted PCR or qPCR approaches. These data also suggest that SARS-CoV-2 or closely related viruses were absent from Wuhan in 2016-2017.

The evolutionary history of vertebrate RNA viruses.

Our understanding of the diversity and evolution of vertebrate RNA viruses is largely limited to those found in mammalian and avian hosts and associated with overt disease. Here, using a large-scale meta-transcriptomic approach, we discover 214 vertebrate-associated viruses in reptiles, amphibians, lungfish, ray-finned fish, cartilaginous fish and jawless fish. The newly discovered viruses appear in every family or genus of RNA virus associated with vertebrate infection, including those containing human pathogens such as influenza virus, the Arenaviridae and Filoviridae families, and have branching orders that broadly reflected the phylogenetic history of their hosts. We establish a long evolutionary history for most groups of vertebrate RNA virus, and support this by evaluating evolutionary timescales using dated orthologous endogenous virus elements. We also identify new vertebrate-specific RNA viruses and genome architectures, and re-evaluate the evolution of vector-borne RNA viruses. In summary, this study reveals diverse virus-host associations across the entire evolutionary history of the vertebrates.

Author Correction: The evolutionary history of vertebrate RNA viruses.

Change history: In this Article, author Li Liu should be associated with affiliation number 5 (College of Marine Sciences, South China Agricultural University, Guangzhou, Guangdong, China), rather than affiliation number 4 (Wenzhou Center for Disease Control and Prevention, Wenzhou, Zhejiang, China). This has been corrected online.

ICTV Virus Taxonomy Profile: Jingchuvirales 2023.

Jingchuvirales is an order of negative-sense RNA viruses with genomes of 9.1-15.3 kb that have been associated with arachnids, barnacles, crustaceans, insects, fish and reptiles in Africa, Asia, Australia, Europe, North America and South America. The jingchuviral genome has two to four open reading frames (ORFs) that encode a glycoprotein (GP), a nucleoprotein (NP), a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain, and/or proteins of unknown function. Viruses in the order are only known from their genome sequences. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the order Jingchuvirales and on the families Aliusviridae, Chuviridae, Crepuscuviridae, Myriaviridae and Natareviridae, which are available at ictv.global/report/jingchuvirales, ictv.global/report/aliusviridae, ictv.global/report/chuviridae, ictv.global/report/crepuscuviridae, ictv.global/report/myriaviridae and ictv.global/report/natareviridae, respectively.

Virome of Bat-Infesting Arthropods: Highly Divergent Viruses in Different Vectors.

Bats are reservoirs of important zoonotic viruses like Nipah and SARS viruses. However, whether the blood-sucking arthropods on the body surface of bats also carry these viruses and the relationship between viruses carried by the blood-sucking arthropods and viruses carried by bats have not been reported. This study collected 686 blood-sucking arthropods on the body surface of bats from Yunnan Province, China, between 2012 and 2015, and they included wingless bat flies, bat flies, ticks, mites, and fleas. The viruses carried by these arthropods were analyzed using a meta-transcriptomic approach, and 144 highly diverse positive-sense single-stranded RNA, negative-sense single-stranded RNA, and double-stranded RNA viruses were found, of which 138 were potentially new viruses. These viruses were classified into 14 different virus families or orders, including Bunyavirales, Mononegavirales, Reoviridae, and Picornavirales. Further analyses found that Bunyavirales were the most abundant virus group (84% of total virus RNA) in ticks, whereas narnaviruses were the most abundant (52 to 92%) in the bat flies and wingless bat flies libraries, followed by solemoviruses (1 to 29%) and reoviruses (0 to 43%). These viruses were highly structured based on the arthropod types. It is worth noting that no bat-borne zoonotic viruses were found in the virome of bat-infesting arthropod, seemingly not supporting that bat surface arthropods are vectors of zoonotic viruses carried by bats. IMPORTANCE Bats are reservoirs of many important viral pathogens. To evaluate whether bat-parasitic blood-sucking arthropods participate in the circulation of these important viruses, it is necessary to conduct unbiased virome studies on these arthropods. We evaluated five types of blood-sucking parasitic arthropods on the surface of bats in Yunnan, China, and identified a variety of viruses, some of which had high prevalence and abundance levels, although there is limited overlap in virome between distant arthropods. While most of the virome discovered here is potentially arthropod-specific viruses, we identified three possible arboviruses, including one orthobunyavirus and two vesiculoviruses (family Rhabdoviridae), suggesting bat-parasitic arthropods carry viruses with risk of spillage, which warrants further study.

Hierarchical metacommunity structure of fungal endophytes.

The ecological and evolutionary processes shaping community structure and functions of microbial symbionts are known to be scale-dependent. Nonetheless, understanding how the relative importance of these processes changes across spatial scales, and deciphering the hierarchical metacommunity structure of fungal endophytes has proven challenging. We investigated metacommunities of endophytic fungi within leaves of an invasive plant (Alternanthera philoxeroides) across wide latitudinal transects both in its native (Argentina) and introduced (China) ranges to test whether metacommunities of fungal endophytes were structured by different drivers at different spatial scales. We found Clementsian structures with seven discrete compartments (distinctive groups of fungal species with coincident distribution ranges), which coincided with the distribution of major watersheds. Metacommunity compartments were explicitly demarcated at three spatial scales, that is, the between-continent, between-compartment, and within-compartment scales. At larger spatial scales, local environmental conditions (climate, soil, and host plant traits) were replaced by other geographical factors as principal determinants of metacommunity structure of fungal endophytes and community diversity-function relationships. Our results reveal novel insights into the scale dependency of diversity and functions of fungal endophytes, which are likely similar for plant symbionts. These findings can potentially improve our understanding of the global patterns of fungal diversity.

Dysbiosis of oropharyngeal microbiome and antibiotic resistance in hospitalized COVID-19 patients.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is ongoing and multiple studies have elucidated its pathogenesis, however, the related- microbiome imbalance caused by SARS-CoV-2 is still not clear. In this study, we have comprehensively compared the microbiome composition and associated function alterations in the oropharyngeal swabs of healthy controls and coronavirus disease 2019 (COVID-19) patients with moderate or severe symptoms by metatranscriptomic sequencing. We did observe a reduced microbiome alpha-diversity but significant enrichment of opportunistic microorganisms in patients with COVID-19 compared with healthy controls, and the microbial homeostasis was rebuilt following the recovery of COVID-19 patients. Correspondingly, less functional genes in multiple biological processes and weakened metabolic pathways such as carbohydrate metabolism, energy metabolism were also observed in COVID-19 patients. We only found higher relative abundance of limited genera such as Lachnoanaerobaculum between severe patients and moderate patients while no worthy-noting microbiome diversity and function alteration were observed. Finally, we noticed that the co-occurrence of antibiotic resistance and virulence was closely related to the microbiome alteration caused by SRAS-CoV-2. Overall, our findings demonstrate that microbial dysbiosis may enhance the pathogenesis of SARS-CoV-2 and the antibiotics treatment should be critically considered.

ICTV Virus Taxonomy Profile: Rhabdoviridae 2022.

The family Rhabdoviridae comprises viruses with negative-sense (-) RNA genomes of 10-16 kb. Virions are typically enveloped with bullet-shaped or bacilliform morphology but can also be non-enveloped filaments. Rhabdoviruses infect plants or animals, including mammals, birds, reptiles, amphibians or fish, as well as arthropods, which serve as single hosts or act as biological vectors for transmission to animals or plants. Rhabdoviruses include important pathogens of humans, livestock, fish or agricultural crops. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Rhabdoviridae, which is available at ictv.global/report/rhabdoviridae.

Jingchuvirales: a New Taxonomical Framework for a Rapidly Expanding Order of Unusual Monjiviricete Viruses Broadly Distributed among Arthropod Subphyla.

Technical advances in metagenomics and metatranscriptomics have dramatically accelerated virus discovery in recent years. "Chuviruses" were first described in 2015 as obscure negative-sense RNA viruses of diverse arthropods. Although "chuviruses" first appeared to be members of the negarnaviricot order Mononegavirales in phylogenetic analyses using RNA-directed RNA polymerase sequences, further characterization revealed unusual gene orders in genomes that are nonsegmented, segmented, and/or possibly circular. Consequently, a separate order, Jingchuvirales, was established to include a monospecific family, Chuviridae. Recently, it has become apparent that jingchuvirals are broadly distributed and are therefore likely of ecological and economic importance. Here, we describe recent and ongoing efforts to create the necessary taxonomic framework to accommodate the expected flood of novel viruses belonging to the order.

Redefining the invertebrate RNA virosphere.

Current knowledge of RNA virus biodiversity is both biased and fragmentary, reflecting a focus on culturable or disease-causing agents. Here we profile the transcriptomes of over 220 invertebrate species sampled across nine animal phyla and report the discovery of 1,445 RNA viruses, including some that are sufficiently divergent to comprise new families. The identified viruses fill major gaps in the RNA virus phylogeny and reveal an evolutionary history that is characterized by both host switching and co-divergence. The invertebrate virome also reveals remarkable genomic flexibility that includes frequent recombination, lateral gene transfer among viruses and hosts, gene gain and loss, and complex genomic rearrangements. Together, these data present a view of the RNA virosphere that is more phylogenetically and genomically diverse than that depicted in current classification schemes and provide a more solid foundation for studies in virus ecology and evolution.

RNA virome diversity and Wolbachia infection in individual Drosophila simulans flies.

The endosymbiont bacteria of the genus Wolbachia are associated with multiple mutualistic effects on insect biology, including nutritional and antiviral properties. Members of the genus Wolbachia naturally occur in fly species of the genus Drosophila, providing an operational model host for studying how virome composition may be affected by its presence. Drosophila simulans populations can carry a variety of strains of members of the genus Wolbachia, with the wAu strain associated with strong antiviral protection under experimental conditions. We used D. simulans sampled from the Perth Hills, Western Australia, to investigate the potential virus protective effect of the wAu strain of Wolbachia on individual wild-caught flies. Our data revealed no appreciable variation in virus composition and abundance between individuals infected or uninfected with Wolbachia associated with the presence or absence of wAu. However, it remains unclear whether wAu might affect viral infection and host survival by increasing tolerance rather than inducing complete resistance. These data also provide new insights into the natural virome diversity of D. simulans. Despite the small number of individuals sampled, we identified a repertoire of RNA viruses, including nora virus, galbut virus, thika virus and La Jolla virus, that have been identified in other species of the genus Drosophila. Chaq virus-like sequences associated with galbut virus were also detected. In addition, we identified five novel viruses from the families Reoviridae, Tombusviridae, Mitoviridae and Bunyaviridae. Overall, this study highlights the complex interaction between Wolbachia and RNA virus infections and provides a baseline description of the natural virome of D. simulans.

Comparative Analysis of RNA Virome Composition in Rabbits and Associated Ectoparasites.

Ectoparasites play an important role in virus transmission among vertebrates. Little, however, is known about the nature of those viruses that pass between invertebrates and vertebrates. In Australia, flies and fleas support the mechanical transmission of two viral biological controls against wild rabbits-rabbit hemorrhagic disease virus (RHDV) and myxoma virus. We compared virome compositions in rabbits and these ectoparasites, sequencing total RNA from multiple tissues and gut contents of wild rabbits, fleas collected from these rabbits, and flies trapped sympatrically. Meta-transcriptomic analyses identified 50 novel viruses from multiple RNA virus families. Rabbits and their ectoparasites were characterized by markedly different viromes, with virus abundance greatest in flies. Although viral contigs from six virus families/groups were found in both rabbits and ectoparasites, they clustered in distinct host-dependent lineages. A novel calicivirus and a picornavirus detected in rabbit cecal content were vertebrate specific; the newly detected calicivirus was distinct from known rabbit caliciviruses, while the picornavirus clustered with sapeloviruses. Several picobirnaviruses were also identified that fell in diverse phylogenetic positions, compatible with the idea that they are associated with bacteria. Further comparative analysis revealed that the remaining viruses found in rabbits, and all those from ectoparasites, were likely associated with invertebrates, plants, and coinfecting endosymbionts. While no full genomes of vertebrate-associated viruses were detected in ectoparasites, small numbers of reads from rabbit astrovirus, RHDV, and other lagoviruses were present in flies. This supports a role for flies in the mechanical transmission of RHDV, while their involvement in astrovirus transmission merits additional exploration.IMPORTANCE Ectoparasites play an important role in the transmission of many vertebrate-infecting viruses, including Zika and dengue viruses. Although it is becoming increasingly clear that invertebrate species harbor substantial virus diversity, it is unclear how many of the viruses carried by invertebrates have the potential to infect vertebrate species. We used the European rabbit (Oryctolagus cuniculus) as a model species to compare virome compositions in a vertebrate host and known associated ectoparasite mechanical vectors, in this case, fleas and blowflies. In particular, we aimed to infer the extent of viral transfer between these distinct types of host. Our analysis revealed that despite extensive viral diversity in both rabbits and associated ectoparasites, and the close interaction of these vertebrate and invertebrate species, biological viral transmission from ectoparasites to vertebrate species is rare. We did, however, find evidence to support the idea of a role of blowflies in transmitting viruses without active replication in the insect.

Metatranscriptomic Analysis of Virus Diversity in Urban Wild Birds with Paretic Disease.

Wild birds are major natural reservoirs and potential dispersers of a variety of infectious diseases. As such, it is important to determine the diversity of viruses they carry and use this information to help understand the potential risks of spillover to humans, domestic animals, and other wildlife. We investigated the potential viral causes of paresis in long-standing, but undiagnosed, disease syndromes in wild Australian birds. RNA from diseased birds was extracted and pooled based on tissue type, host species, and clinical manifestation for metagenomic sequencing. Using a bulk and unbiased metatranscriptomic approach, combined with clinical investigation and histopathology, we identified a number of novel viruses from the families Astroviridae, Adenoviridae, Picornaviridae, Polyomaviridae, Paramyxoviridae, Parvoviridae, and Circoviridae in common urban wild birds, including Australian magpies, magpie larks, pied currawongs, Australian ravens, and rainbow lorikeets. In each case, the presence of the virus was confirmed by reverse transcription (RT)-PCR. These data revealed a number of candidate viral pathogens that may contribute to coronary, skeletal muscle, vascular, and neuropathology in birds of the Corvidae and Artamidae families and neuropathology in members of the Psittaculidae The existence of such a diverse virome in urban avian species highlights the importance and challenges in elucidating the etiology and ecology of wildlife pathogens in urban environments. This information will be increasingly important for managing disease risks and conducting surveillance for potential viral threats to wildlife, livestock, and human health.IMPORTANCE Wildlife naturally harbor a diverse array of infectious microorganisms and can be a source of novel diseases in domestic animals and human populations. Using unbiased RNA sequencing, we identified highly diverse viruses in native birds from Australian urban environments presenting with paresis. This research included the clinical investigation and description of poorly understood recurring syndromes of unknown etiology: clenched claw syndrome and black and white bird disease. As well as identifying a range of potentially disease-causing viral pathogens, this study describes methods that can effectively and efficiently characterize emergent disease syndromes in free-ranging wildlife and promotes further surveillance for specific pathogens of potential conservation and zoonotic concern.

Meta-Transcriptomic Analysis Reveals the Virome and Viral Genomic Evolution of Medically Important Mites.

Mites are notorious for being vectors transmitting infectious pathogens and source of allergens causing allergic conditions in animals and humans. However, despite their huge impact on public health, the virome of mites remains unknown. Here we characterized the virus diversity and abundance of 14 species of medically important mites based on total RNA sequencing data sets generated in this study as well as those deposited in the Sequence Read Archive (SRA) database. A total of 47 genetically distinct viruses were identified and classified into 17 virus families or virus super-groups, and the viral sequences accounted for as much as 29.67% of total non-rRNA transcriptome in one mite library. The most commonly identified viruses are members of Picornavirales, among which we revealed more than one type of viruses that are evolutionarily related to dicistronic viruses but contain a single open reading frame, thus likely representing a recent example of host (i.e., mite)-related parallel evolution from dicistronic to monocistronic genomic form within the family Dicistroviridae To our best knowledge, this is the first time to perform comprehensive and systematic screening of RNA virome in medically important mites including house dust mites (HDM). Overall, the RNA virome identified here provides not only significant insights into the diversity and evolution of RNA viruses in mites, but also a solid knowledge base for studying their roles in human diseases.IMPORTANCE Mites are important group of arthropods that are associated with a variety of human diseases including scrub typhus and asthma. However, it remains unclear whether or not mites carry viruses that might play a role in human infections or allergic disease. In this study, we used a total transcriptomics approach to characterize and compare the complete RNA virome within mites that are relevant to human health and diseases. Specifically, our data revealed a large diversity, a high abundance, and a flexible genomic evolution for these viruses. Although most of the viruses identified here are unknown to associate with human infectious disease, the abundant presence of viral RNAs may play an immunomodulatory role in the development of allergic reactions such as asthma during environmental exposure to mite allergens, and therefore provide important insights into the mite-induced allergy and preparation of mite allergen vaccines.