archaeal viruses
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2021 ◽  
Vol 2 (4) ◽  
pp. 100791
Author(s):  
Lauge Alfastsen ◽  
Xu Peng ◽  
Yuvaraj Bhoobalan-Chitty

PLoS Biology ◽  
2021 ◽  
Vol 19 (11) ◽  
pp. e3001442
Author(s):  
Ying Liu ◽  
Tatiana A. Demina ◽  
Simon Roux ◽  
Pakorn Aiewsakun ◽  
Darius Kazlauskas ◽  
...  

The archaeal tailed viruses (arTV), evolutionarily related to tailed double-stranded DNA (dsDNA) bacteriophages of the class Caudoviricetes, represent the most common isolates infecting halophilic archaea. Only a handful of these viruses have been genomically characterized, limiting our appreciation of their ecological impacts and evolution. Here, we present 37 new genomes of haloarchaeal tailed virus isolates, more than doubling the current number of sequenced arTVs. Analysis of all 63 available complete genomes of arTVs, which we propose to classify into 14 new families and 3 orders, suggests ancient divergence of archaeal and bacterial tailed viruses and points to an extensive sharing of genes involved in DNA metabolism and counter defense mechanisms, illuminating common strategies of virus–host interactions with tailed bacteriophages. Coupling of the comparative genomics with the host range analysis on a broad panel of haloarchaeal species uncovered 4 distinct groups of viral tail fiber adhesins controlling the host range expansion. The survey of metagenomes using viral hallmark genes suggests that the global architecture of the arTV community is shaped through recurrent transfers between different biomes, including hypersaline, marine, and anoxic environments.


Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2126
Author(s):  
Victoria Turzynski ◽  
Indra Monsees ◽  
Cristina Moraru ◽  
Alexander J. Probst

Viruses are the most abundant biological entities on Earth with an estimate of 1031 viral particles across all ecosystems. Prokaryotic viruses—bacteriophages and archaeal viruses—influence global biogeochemical cycles by shaping microbial communities through predation, through the effect of horizontal gene transfer on the host genome evolution, and through manipulating the host cellular metabolism. Imaging techniques have played an important role in understanding the biology and lifestyle of prokaryotic viruses. Specifically, structure-resolving microscopy methods, for example, transmission electron microscopy, are commonly used for understanding viral morphology, ultrastructure, and host interaction. These methods have been applied mostly to cultivated phage–host pairs. However, recent advances in environmental genomics have demonstrated that the majority of viruses remain uncultivated, and thus microscopically uncharacterized. Although light- and structure-resolving microscopy of viruses from environmental samples is possible, quite often the link between the visualization and the genomic information of uncultivated prokaryotic viruses is missing. In this minireview, we summarize the current state of the art of imaging techniques available for characterizing viruses in environmental samples and discuss potential links between viral imaging and environmental genomics for shedding light on the morphology of uncultivated viruses and their lifestyles in Earth’s ecosystems.


2021 ◽  
Author(s):  
Ian Rambo ◽  
Valerie De Anda ◽  
Marguerite Langwig ◽  
Brett Baker

Abstract Asgard archaea are globally distributed, newly described microbes related to eukaryotes. Despite their importance, Asgard viruses have not been described. Here we characterize seven double-stranded DNA (dsDNA) viral genomes that infected Lokiarchaeota, Helarchaeota, and Thorarchaeota in deep-sea hydrothermal sediments. These viruses code for Caudovirales-like structural proteins, as well as proteins distinct from those described in archaeal viruses. They contain genes common in eukaryotic nucleocytoplasmic large DNA viruses (NCLDVs), and appear to be capable of semi-autonomous genome replication, repair, epigenetic modifications, and transcriptional regulation. Moreover, Helarchaeota viruses may hijack host ubiquitin systems similar to eukaryotic viruses. Recovery of these Asgard viral genomes reveals they contain features of both prokaryotic and eukaryotic viruses, and provides insights into their roles in the ecology and evolution of their hosts.


2021 ◽  
Author(s):  
Diana P. Baquero ◽  
Junfeng Liu ◽  
David Prangishvili
Keyword(s):  

2021 ◽  
Author(s):  
Daniel Tamarit ◽  
Eva F Caceres ◽  
Mart Krupovic ◽  
Reindert Nijland ◽  
Laura Eme ◽  
...  

Asgard archaea have recently been identified as the closest archaeal relatives of eukaryotes. Their ecology remains enigmatic, and their virome, completely unknown. Here, we describe the closed genome of Ca. Odinarchaeum yellowstonii LCB_4, and, from this, obtain novel CRISPR arrays with spacer targets to several viral contigs. We find related viruses in sequence data from thermophilic environments and in the genomes of diverse prokaryotes, including other Asgard archaea. These novel viruses open research avenues into the ecology and evolution of Asgard archaea.


Author(s):  
Mart Krupovic ◽  
Dann Turner ◽  
Vera Morozova ◽  
Mike Dyall-Smith ◽  
Hanna M. Oksanen ◽  
...  

AbstractIn this article, we – the Bacterial Viruses Subcommittee and the Archaeal Viruses Subcommittee of the International Committee on Taxonomy of Viruses (ICTV) – summarise the results of our activities for the period March 2020 – March 2021. We report the division of the former Bacterial and Archaeal Viruses Subcommittee in two separate Subcommittees, welcome new members, a new Subcommittee Chair and Vice Chair, and give an overview of the new taxa that were proposed in 2020, approved by the Executive Committee and ratified by vote in 2021. In particular, a new realm, three orders, 15 families, 31 subfamilies, 734 genera and 1845 species were newly created or redefined (moved/promoted).


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Janina Rahlff ◽  
Victoria Turzynski ◽  
Sarah P. Esser ◽  
Indra Monsees ◽  
Till L. V. Bornemann ◽  
...  

AbstractThe continental subsurface houses a major portion of life’s abundance and diversity, yet little is known about viruses infecting microbes that reside there. Here, we use a combination of metagenomics and virus-targeted direct-geneFISH (virusFISH) to show that highly abundant carbon-fixing organisms of the uncultivated genus Candidatus Altiarchaeum are frequent targets of previously unrecognized viruses in the deep subsurface. Analysis of CRISPR spacer matches display resistances of Ca. Altiarchaea against eight predicted viral clades, which show genomic relatedness across continents but little similarity to previously identified viruses. Based on metagenomic information, we tag and image a putatively viral genome rich in protospacers using fluorescence microscopy. VirusFISH reveals a lytic lifestyle of the respective virus and challenges previous predictions that lysogeny prevails as the dominant viral lifestyle in the subsurface. CRISPR development over time and imaging of 18 samples from one subsurface ecosystem suggest a sophisticated interplay of viral diversification and adapting CRISPR-mediated resistances of Ca. Altiarchaeum. We conclude that infections of primary producers with lytic viruses followed by cell lysis potentially jump-start heterotrophic carbon cycling in these subsurface ecosystems.


2021 ◽  
Author(s):  
Ian M Rambo ◽  
Valerie De Anda ◽  
Marguerite V Langwig ◽  
Brett J Baker

Asgard archaea are newly described microbes that are related to eukaryotes. Asgards are diverse and globally distributed, however, their viruses have not been described. Here we characterize seven viral genomes that infected Lokiarchaeota, Helarchaeota, and Thorarchaeota in deep-sea hydrothermal sediments. These viruses code for structural proteins similar to those in Caudovirales, as well as proteins distinct from those described in archaeal viruses. They also have genes common in eukaryotic nucleocytoplasmic large DNA viruses (NCLDVs), and are predicted to be capable of semi-autonomous genome replication, repair, epigenetic modifications, and transcriptional regulation. Moreover, Helarchaeota viruses may hijack host ubiquitin systems similar to eukaryotic viruses. This first glimpse of Asgard viruses reveals they have features of both prokaryotic and eukaryotic viruses, and provides insights into their roles in the ecology and evolution of these globally distributed microbes.


2021 ◽  
Author(s):  
Ying Liu ◽  
Tatiana A. Demina ◽  
Simon Roux ◽  
Pakorn Aiewsakun ◽  
Darius Kazlauskas ◽  
...  

The archaeal tailed viruses (arTV), evolutionarily related to tailed double-stranded DNA bacteriophages of the class Caudoviricetes, represent the most common isolates infecting halophilic archaea. Only a handful of these viruses have been genomically characterized, limiting our appreciation of their ecological impacts and evolution. Here, we present 37 new genomes of haloarchaeal tailed virus isolates, more than doubling the current number of sequenced arTVs. Analysis of all 63 available complete genomes of arTVs, which we propose to classify into 14 new families, suggests ancient divergence of archaeal and bacterial tailed viruses and points to an extensive sharing of genes involved in DNA metabolism and counter defense mechanisms, illuminating common strategies of virus-host interactions with tailed bacteriophages. Coupling of the comparative genomics with the host range analysis on a broad panel of haloarchaeal species uncovered four distinct groups of viral tail fiber adhesins controlling the host range expansion. The survey of metagenomes using viral hallmark genes suggests that the global architecture of the arTV community is shaped through recurrent transfers between different biomes, including hypersaline, marine and anoxic environments.


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