The ongoing pandemic of a new human coronavirus, SARS-CoV-2, has generated enormous global concern. We and others in China were involved in the initial genome sequencing of the virus. Herein, we ...describe what genomic data reveal about the emergence SARS-CoV-2 and discuss the gaps in our understanding of its origins.
COVID-19-lessons for zoonotic disease Holmes, Edward C
Science (American Association for the Advancement of Science),
2022-Mar-11, Volume:
375, Issue:
6585
Journal Article
Peer reviewed
Disease emergence is driven by human-animal contact in a global viral ecosystem.
Identifying the animal reservoirs from which zoonotic viruses will likely emerge is central to understanding the determinants of disease emergence. Accordingly, there has been an increase in studies ...attempting zoonotic "risk assessment." Herein, we demonstrate that the virological data on which these analyses are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery. Together, these shortcomings suggest that attempts to assess zoonotic risk using available virological data are likely to be inaccurate and largely only identify those host taxa that have been studied most extensively. We suggest that virus surveillance at the human-animal interface may be more productive.
The cross-species transmission of viruses from one host species to another is responsible for the majority of emerging infections. However, it is unclear whether some virus families have a greater ...propensity to jump host species than others. If related viruses have an evolutionary history of co-divergence with their hosts there should be evidence of topological similarities between the virus and host phylogenetic trees, whereas host jumping generates incongruent tree topologies. By analyzing co-phylogenetic processes in 19 virus families and their eukaryotic hosts we provide a quantitative and comparative estimate of the relative frequency of virus-host co-divergence versus cross-species transmission among virus families. Notably, our analysis reveals that cross-species transmission is a near universal feature of the viruses analyzed here, with virus-host co-divergence occurring less frequently and always on a subset of viruses. Despite the overall high topological incongruence among virus and host phylogenies, the Hepadnaviridae, Polyomaviridae, Poxviridae, Papillomaviridae and Adenoviridae, all of which possess double-stranded DNA genomes, exhibited more frequent co-divergence than the other virus families studied here. At the other extreme, the virus and host trees for all the RNA viruses studied here, particularly the Rhabdoviridae and the Picornaviridae, displayed high levels of topological incongruence, indicative of frequent host switching. Overall, we show that cross-species transmission plays a major role in virus evolution, with all the virus families studied here having the potential to jump host species, and that increased sampling will likely reveal more instances of host jumping.
Endogenous retroviruses are a common component of the eukaryotic genome, and their evolution and potential function have attracted considerable interest. More surprising was the recent discovery that ...eukaryotic genomes contain sequences from RNA viruses that have no DNA stage in their life cycle. Similarly, several single-stranded DNA viruses have left integrated copies in their host genomes. This review explores some major evolutionary aspects arising from the discovery of these endogenous viral elements (EVEs). In particular, the reasons for the bias toward EVEs derived from negative-sense RNA viruses are considered, as well as what they tell us about the long-term “arms races” between hosts and viruses, characterized by episodes of selection and counter-selection. Most dramatically, the presence of orthologous EVEs in divergent hosts demonstrates that some viral families have ancestries dating back almost 100 million years, and hence are far older than expected from the phylogenetic analysis of their exogenous relatives.
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.
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.
The unprecedented pandemic of pneumonia caused by a novel coronavirus, SARS-CoV-2, in China and beyond has had major public health impacts on a global scale 1, 2. Although bats are regarded as the ...most likely natural hosts for SARS-CoV-2 3, the origins of the virus remain unclear. Here, we report a novel bat-derived coronavirus, denoted RmYN02, identified from a metagenomic analysis of samples from 227 bats collected from Yunnan Province in China between May and October 2019. Notably, RmYN02 shares 93.3% nucleotide identity with SARS-CoV-2 at the scale of the complete virus genome and 97.2% identity in the 1ab gene, in which it is the closest relative of SARS-CoV-2 reported to date. In contrast, RmYN02 showed low sequence identity (61.3%) to SARS-CoV-2 in the receptor-binding domain (RBD) and might not bind to angiotensin-converting enzyme 2 (ACE2). Critically, and in a similar manner to SARS-CoV-2, RmYN02 was characterized by the insertion of multiple amino acids at the junction site of the S1 and S2 subunits of the spike (S) protein. This provides strong evidence that such insertion events can occur naturally in animal betacoronaviruses.
•Metagenomic analysis identified a novel coronavirus, RmYN02, from R. malayanus•RmYN02 was the closest relative of SARS-CoV-2 in most of the virus genome•Two loop deletions in RBD may reduce the binding of RmYN02 with ACE2•RmYN02 contains an insertion at the S1/S2 cleavage site in the spike protein
Zhou et al. report a bat-derived coronavirus, RmYN02, which is the closest relative of SARS-CoV-2 in most of the virus genome reported to date. RmYN02 contains an insertion at the S1/S2 cleavage site in the spike protein in a similar manner to SARS-CoV-2. This suggests that such insertion events can occur naturally in animal betacoronaviruses.
The patterns and processes of influenza virus evolution are of fundamental importance, underpinning such traits as the propensity to emerge in new host species and the ability to rapidly generate ...antigenic variation. Herein, we review key aspects of the ecology and evolution of influenza viruses. We begin with an exploration of the origins of influenza viruses within the orthomyxoviruses, showing how our perception of the evolutionary history of these viruses has been transformed with metagenomic sequencing. We then outline the diversity of virus subtypes in different species and the processes by which these viruses have emerged in new hosts, with a particular focus on the role played by segment reassortment. We then turn our attention to documenting the spread and phylodynamics of seasonal influenza A and B viruses in human populations, including the drivers of antigenic evolution, and finish with a discussion of virus diversity and evolution at the scale of individual hosts.
ABSTRACT
Wild birds interconnect all parts of the globe through annual cycles of migration with little respect for country or continental borders. Although wild birds are reservoir hosts for a high ...diversity of gamma- and deltacoronaviruses, we have little understanding of the ecology or evolution of any of these viruses. In this review, we use genome sequence and ecological data to disentangle the evolution of coronaviruses in wild birds. Specifically, we explore host range at the levels of viral genus and species, and reveal the multi-host nature of many viral species, albeit with biases to certain types of avian host. We conclude that it is currently challenging to infer viral ecology due to major sampling and technical limitations, and suggest that improved assay performance across the breadth of gamma- and deltacoronaviruses, assay standardization, as well as better sequencing approaches, will improve both the repeatability and interpretation of results. Finally, we discuss cross-species virus transmission across both the wild bird – poultry interface as well as from birds to mammals. Clarifying the ecology and diversity in the wild bird reservoir has important ramifications for our ability to respond to the likely future emergence of coronaviruses in socioeconomically important animal species or human populations.
Although wild birds are hosts to numerous species of gammacoronaviruses and deltacoronaviruses, some of which infect domestic birds or are able to spill-over into mammals, we reveal the limitations to our current understanding of their diversity, ecology and evolution.
Aquatic birds harbor diverse influenza A viruses and are a major viral reservoir in nature. The recent discovery of influenza viruses of a new H17N10 subtype in Central American fruit bats suggests ...that other New World species may similarly carry divergent influenza viruses. Using consensus degenerate RT-PCR, we identified a novel influenza A virus, designated as H18N11, in a flat-faced fruit bat (Artibeus planirostris) from Peru. Serologic studies with the recombinant H18 protein indicated that several Peruvian bat species were infected by this virus. Phylogenetic analyses demonstrate that, in some gene segments, New World bats harbor more influenza virus genetic diversity than all other mammalian and avian species combined, indicative of a long-standing host-virus association. Structural and functional analyses of the hemagglutinin and neuraminidase indicate that sialic acid is not a ligand for virus attachment nor a substrate for release, suggesting a unique mode of influenza A virus attachment and activation of membrane fusion for entry into host cells. Taken together, these findings indicate that bats constitute a potentially important and likely ancient reservoir for a diverse pool of influenza viruses.
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