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Koonin EV, Fischer MG, Kuhn JH, Krupovic M. The polinton-like supergroup of viruses: evolution, molecular biology, and taxonomy. Microbiol Mol Biol Rev 2024; 88:e0008623. [PMID: 39023254 PMCID: PMC11426020 DOI: 10.1128/mmbr.00086-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024] Open
Abstract
SUMMARYPolintons are 15-20 kb-long self-synthesizing transposons that are widespread in eukaryotic, and in particular protist, genomes. Apart from a transposase and a protein-primed DNA polymerase, polintons encode homologs of major and minor jelly-roll capsid proteins, DNA-packaging ATPases, and proteases involved in capsid maturation of diverse eukaryotic viruses of kingdom Bamfordvirae. Given the conservation of these structural and morphogenetic proteins among polintons, these elements are predicted to alternate between transposon and viral lifestyles and, although virions have thus far not been detected, are classified as viruses (class Polintoviricetes) in the phylum Preplasmiviricota. Related to polintoviricetes are vertebrate adenovirids; unclassified polinton-like viruses (PLVs) identified in various environments or integrated into diverse protist genomes; virophages (Maveriviricetes), which are part of tripartite hyperparasitic systems including protist hosts and giant viruses; and capsid-less derivatives, such as cytoplasmic linear DNA plasmids of fungi and transpovirons. Phylogenomic analysis indicates that the polinton-like supergroup of viruses bridges bacterial tectivirids (preplasmiviricot class Tectiliviricetes) to the phylum Nucleocytoviricota that includes large and giant eukaryotic DNA viruses. Comparative structural analysis of proteins encoded by polinton-like viruses led to the discovery of previously undetected functional domains, such as terminal proteins and distinct proteases implicated in DNA polymerase processing, and clarified the evolutionary relationships within Polintoviricetes. Here, we leverage these insights into the evolution of the polinton-like supergroup to develop an amended megataxonomy that groups Polintoviricetes, PLVs (new class 'Aquintoviricetes'), and virophages (renamed class 'Virophaviricetes') together with Adenoviridae (new class 'Pharingeaviricetes') in a preplasmiviricot subphylum 'Polisuviricotina' sister to a subphylum including Tectiliviricetes ('Prepoliviricotina').
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Matthias G Fischer
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, Division of Clinical Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Fort Detrick, Frederick, Maryland, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, Archaeal Virology Unit, Paris, France
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2
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Tokarz-Deptuła B, Chrzanowska S, Baraniecki Ł, Gurgacz N, Stosik M, Sobolewski J, Deptuła W. Virophages, Satellite Viruses, Virophage Replication and Its Effects and Virophage Defence Mechanisms for Giant Virus Hosts and Giant Virus Defence Systems against Virophages. Int J Mol Sci 2024; 25:5878. [PMID: 38892066 PMCID: PMC11172284 DOI: 10.3390/ijms25115878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/22/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
In this paper, the characteristics of 40 so far described virophages-parasites of giant viruses-are given, and the similarities and differences between virophages and satellite viruses, which also, like virophages, require helper viruses for replication, are described. The replication of virophages taking place at a specific site-the viral particle factory of giant viruses-and its consequences are presented, and the defence mechanisms of virophages for giant virus hosts, as a protective action for giant virus hosts-protozoa and algae-are approximated. The defence systems of giant viruses against virophages were also presented, which are similar to the CRISPR/Cas defence system found in bacteria and in Archea. These facts, and related to the very specific biological features of virophages (specific site of replication, specific mechanisms of their defensive effects for giant virus hosts, defence systems in giant viruses against virophages), indicate that virophages, and their host giant viruses, are biological objects, forming a 'novelty' in biology.
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Affiliation(s)
| | - Sara Chrzanowska
- Institute of Biology, University of Szczecin, 71-412 Szczecin, Poland (Ł.B.)
| | - Łukasz Baraniecki
- Institute of Biology, University of Szczecin, 71-412 Szczecin, Poland (Ł.B.)
| | - Natalia Gurgacz
- Institute of Biology, University of Szczecin, 71-412 Szczecin, Poland (Ł.B.)
| | - Michał Stosik
- Institute of Biological Science, Faculty of Biological Sciences, University of Zielona Góra, 65-516 Zielona Góra, Poland;
| | - Jarosław Sobolewski
- Institute of Veterinary Medicine, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland;
| | - Wiesław Deptuła
- Institute of Veterinary Medicine, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland;
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3
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Cho A, Lax G, Livingston SJ, Masukagami Y, Naumova M, Millar O, Husnik F, Keeling PJ. Genomic analyses of Symbiomonas scintillans show no evidence for endosymbiotic bacteria but does reveal the presence of giant viruses. PLoS Genet 2024; 20:e1011218. [PMID: 38557755 PMCID: PMC11008856 DOI: 10.1371/journal.pgen.1011218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 04/11/2024] [Accepted: 03/11/2024] [Indexed: 04/04/2024] Open
Abstract
Symbiomonas scintillans Guillou et Chrétiennot-Dinet, 1999 is a tiny (1.4 μm) heterotrophic microbial eukaryote. The genus was named based on the presence of endosymbiotic bacteria in its endoplasmic reticulum, however, like most such endosymbionts neither the identity nor functional association with its host were known. We generated both amplification-free shotgun metagenomics and whole genome amplification sequencing data from S. scintillans strains RCC257 and RCC24, but were unable to detect any sequences from known lineages of endosymbiotic bacteria. The absence of endobacteria was further verified with FISH analyses. Instead, numerous contigs in assemblies from both RCC24 and RCC257 were closely related to prasinoviruses infecting the green algae Ostreococcus lucimarinus, Bathycoccus prasinos, and Micromonas pusilla (OlV, BpV, and MpV, respectively). Using the BpV genome as a reference, we assembled a near-complete 190 kbp draft genome encoding all hallmark prasinovirus genes, as well as two additional incomplete assemblies of closely related but distinct viruses from RCC257, and three similar draft viral genomes from RCC24, which we collectively call SsVs. A multi-gene tree showed the three SsV genome types branched within highly supported clades with each of BpV2, OlVs, and MpVs, respectively. Interestingly, transmission electron microscopy also revealed a 190 nm virus-like particle similar the morphology and size of the endosymbiont originally reported in S. scintillans. Overall, we conclude that S. scintillans currently does not harbour an endosymbiotic bacterium, but is associated with giant viruses.
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Affiliation(s)
- Anna Cho
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Gordon Lax
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Samuel J. Livingston
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yumiko Masukagami
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Mariia Naumova
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Olivia Millar
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Filip Husnik
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Patrick J. Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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Koslová A, Hackl T, Bade F, Sanchez Kasikovic A, Barenhoff K, Schimm F, Mersdorf U, Fischer MG. Endogenous virophages are active and mitigate giant virus infection in the marine protist Cafeteria burkhardae. Proc Natl Acad Sci U S A 2024; 121:e2314606121. [PMID: 38446847 PMCID: PMC10945749 DOI: 10.1073/pnas.2314606121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/14/2024] [Indexed: 03/08/2024] Open
Abstract
Endogenous viral elements (EVEs) are common genetic passengers in various protists. Some EVEs represent viral fossils, whereas others are still active. The marine heterotrophic flagellate Cafeteria burkhardae contains several EVE types related to the virophage mavirus, a small DNA virus that parasitizes the lytic giant virus CroV. We hypothesized that endogenous virophages may act as an antiviral defense system in protists, but no protective effect of virophages in wild host populations has been shown so far. Here, we tested the activity of virophage EVEs and studied their impact on giant virus replication. We found that endogenous mavirus-like elements (EMALEs) from globally distributed Cafeteria populations produced infectious virus particles specifically in response to CroV infection. However, reactivation was stochastic, often inefficient, and poorly reproducible. Interestingly, only one of eight EMALE types responded to CroV infection, implying that other EMALEs may be linked to different giant viruses. We isolated and cloned several reactivated virophages and characterized their particles, genomes, and infection dynamics. All tested virophages inhibited the production of CroV during coinfection, thereby preventing lysis of the host cultures in a dose-dependent manner. Comparative genomics of different C. burkhardae strains revealed that inducible EMALEs are common and are not linked to specific geographic locations. We demonstrate that naturally occurring virophage EVEs reactivate upon giant virus infection, thus providing a striking example that eukaryotic EVEs can become active under specific conditions. Moreover, our results support the hypothesis that virophages can act as an adaptive antiviral defense system in protists.
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Affiliation(s)
- Anna Koslová
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
| | - Thomas Hackl
- Faculty of Science and Engineering, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen9747 AG, The Netherlands
| | - Felix Bade
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
| | | | - Karina Barenhoff
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
| | - Fiona Schimm
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
| | - Ulrike Mersdorf
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
| | - Matthias G. Fischer
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg69120, Germany
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5
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Potapov SA, Belykh OI. Virophages Found in Viromes from Lake Baikal. Biomolecules 2023; 13:1773. [PMID: 38136644 PMCID: PMC10741620 DOI: 10.3390/biom13121773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
In this study, a previously little-studied group of viruses-virophages-was searched for and identified in the viromes of the ancient oligotrophic Lake Baikal. Virophages are small dsDNA viruses that parasitize giant viruses (e.g., Mimiviridae), which in turn affect unicellular eukaryotes. We analyzed eight viromes obtained from the deep-water areas of three basins of Lake Baikal and the shallow-water strait Maloye More in different seasons. The sequences of virophages were revealed in all viromes and were dominant after bacteriophages and algal viruses. Sixteen putative complete genomes of virophages were assembled, all of which contained four conserved genes encoding major capsid protein (MCP), minor capsid protein (mCP), maturation cysteine protease (PRO), and FtsK-HerA family DNA-packaging ATPase (ATPase). The MCP-based cluster analysis showed a sequence separation according to seasons, and a dependence on the geographical localization was not detected.
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Affiliation(s)
- Sergey Anatoljevich Potapov
- Limnological Institute Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya 3, Irkutsk 664033, Russia;
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Tokarz-Deptuła B, Chrzanowska S, Gurgacz N, Stosik M, Deptuła W. Virophages-Known and Unknown Facts. Viruses 2023; 15:1321. [PMID: 37376621 PMCID: PMC10301787 DOI: 10.3390/v15061321] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/31/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023] Open
Abstract
The paper presents virophages, which, like their host, giant viruses, are "new" infectious agents whose role in nature, including mammalian health, is important. Virophages, along with their protozoan and algal hosts, are found in fresh inland waters and oceanic and marine waters, including thermal waters and deep-sea vents, as well as in soil, plants, and in humans and animals (ruminants). Representing "superparasitism", almost all of the 39 described virophages (except Zamilon) interact negatively with giant viruses by affecting their replication and morphogenesis and their "adaptive immunity". This causes them to become regulators and, at the same time, defenders of the host of giant viruses protozoa and algae, which are organisms that determine the homeostasis of the aquatic environment. They are classified in the family Lavidaviridae with two genus (Sputnikovirus, Mavirus). However, in 2023, a proposal was presented that they should form the class Maveriviricetes, with four orders and seven families. Their specific structure, including their microsatellite (SSR-Simple Sequence Repeats) and the CVV (cell-virus-virophage, or transpovirion) system described with them, as well as their function, makes them, together with the biological features of giant viruses, form the basis for discussing the existence of a fourth domain in addition to Bacteria, Archaea, and Eukaryota. The paper also presents the hypothetical possibility of using them as a vector for vaccine antigens.
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Affiliation(s)
| | - Sara Chrzanowska
- Institute of Biology, University of Szczecin, 71-412 Szczecin, Poland
| | - Natalia Gurgacz
- Institute of Biology, University of Szczecin, 71-412 Szczecin, Poland
| | - Michał Stosik
- Institute of Biological Science, Faculty of Biological Sciences, University of Zielona Góra, 65-417 Zielona Góra, Poland
| | - Wiesław Deptuła
- Institute of Veterinary Medicine, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University of Toruń, 87-100 Toruń, Poland
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7
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Xu Y, Wang H, Sahu SK, Li L, Liang H, Günther G, Wong GKS, Melkonian B, Melkonian M, Liu H, Wang S. Chromosome-level genome of Pedinomonas minor (Chlorophyta) unveils adaptations to abiotic stress in a rapidly fluctuating environment. THE NEW PHYTOLOGIST 2022; 235:1409-1425. [PMID: 35560066 DOI: 10.1111/nph.18220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The Pedinophyceae (Viridiplantae) comprise a class of small uniflagellate algae with a pivotal position in the phylogeny of the Chlorophyta as the sister group of the 'core chlorophytes'. We present a chromosome-level genome assembly of the freshwater type species of the class, Pedinomonas minor. We sequenced the genome using Pacbio, Illumina and Hi-C technologies, performed comparative analyses of genome and gene family evolution, and analyzed the transcriptome under various abiotic stresses. Although the genome is relatively small (55 Mb), it shares many traits with core chlorophytes including number of introns and protein-coding genes, messenger RNA (mRNA) lengths, and abundance of transposable elements. Pedinomonas minor is only bounded by the plasma membrane, thriving in temporary habitats that frequently dry out. Gene family innovations and expansions and transcriptomic responses to abiotic stresses have shed light on adaptations of P. minor to its fluctuating environment. Horizontal gene transfers from bacteria and fungi have possibly contributed to the evolution of some of these traits. We identified a putative endogenization site of a nucleocytoplasmic large DNA virus and hypothesized that endogenous viral elements donated foreign genes to the host genome, their spread enhanced by transposable elements, located at gene boundaries in several of the expanded gene families.
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Affiliation(s)
- Yan Xu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 10049, China
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Hongli Wang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 10049, China
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Sunil Kumar Sahu
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Linzhou Li
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, 2800, Denmark
| | - Hongping Liang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 10049, China
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Gerd Günther
- Private Laboratory, Knittkuhler Str. 61, Düsseldorf, 40629, Germany
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada
- Department of Medicine, University of Alberta, Edmonton, AB, T6G 2E9, Canada
| | - Barbara Melkonian
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, 50829, Germany
| | - Michael Melkonian
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, 50829, Germany
| | - Huan Liu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 10049, China
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Sibo Wang
- State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen, 518083, China
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Aylward FO, Moniruzzaman M. Viral Complexity. Biomolecules 2022; 12:1061. [PMID: 36008955 PMCID: PMC9405923 DOI: 10.3390/biom12081061] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 12/18/2022] Open
Abstract
Although traditionally viewed as streamlined and simple, discoveries over the last century have revealed that viruses can exhibit surprisingly complex physical structures, genomic organization, ecological interactions, and evolutionary histories. Viruses can have physical dimensions and genome lengths that exceed many cellular lineages, and their infection strategies can involve a remarkable level of physiological remodeling of their host cells. Virus-virus communication and widespread forms of hyperparasitism have been shown to be common in the virosphere, demonstrating that dynamic ecological interactions often shape their success. And the evolutionary histories of viruses are often fraught with complexities, with chimeric genomes including genes derived from numerous distinct sources or evolved de novo. Here we will discuss many aspects of this viral complexity, with particular emphasis on large DNA viruses, and provide an outlook for future research.
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Affiliation(s)
- Frank O. Aylward
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-Borne Pathogens, Virginia Tech, Blacksburg, VA 24061, USA
| | - Mohammad Moniruzzaman
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables, FL 33149, USA;
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Chase EE, Desnues C, Blanc G. Integrated Viral Elements Suggest the Dual Lifestyle of Tetraselmis Spp. Polinton-Like Viruses. Virus Evol 2022; 8:veac068. [PMID: 35949392 PMCID: PMC9356565 DOI: 10.1093/ve/veac068] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/30/2022] [Accepted: 07/21/2022] [Indexed: 12/03/2022] Open
Abstract
In this study, we aimed at exploring horizontal gene transfer between viruses and Chlorodendraceae green algae (Chlorophyta) using available genomic and transcriptomic sequences for twenty algal strains. We identified a significant number of genes sharing a higher sequence similarity with viral homologues, thus signalling their possible involvement in horizontal gene transfers with viruses. Further characterization showed that many of these genes were clustered in DNA regions of several tens to hundreds of kilobases in size, originally belonging to viruses related to known Tetraselmis spp. viruses (TetV and TsV). In contrast, the remaining candidate HGT genes were randomly dispersed in the algal genomes, were more frequently transcribed, and belonged to large multigene families. The presence of homologues in Viridiplantae suggested that the latter were more likely of algal rather than viral origin. We found a remarkable diversity in polinton-like virus (PLV) elements inserted in Tetraselmis genomes, all of which were most similar to the Tetraselmis striata virus (TsV). The genes of PLV elements are transcriptionally inactive with the notable exception of the homologue of the TVSG_00024 gene of TsV whose function is unknown. We suggest that this gene may be involved in a sentinel process to trigger virus reactivation and excision in response to an environmental stimulus. Altogether, these results provide evidence that TsV-related viruses have a dual lifestyle, alternating between a free viral phase (i.e. virion) and a phase integrated into host genomes.
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Affiliation(s)
- Emily E Chase
- Microbiologie Environnementale Biotechnologie, Institut Méditerranéen d’Océanologie, Campus de Luminy , 163 Avenue de Luminy, 13009 Marseille, France
- Institut hospitalo-universitaire (IHU) Méditerranée infection , 19-21 Boulevard Jean Moulin, 13005 Marseille, France
| | - Christelle Desnues
- Microbiologie Environnementale Biotechnologie, Institut Méditerranéen d’Océanologie, Campus de Luminy , 163 Avenue de Luminy, 13009 Marseille, France
- Institut hospitalo-universitaire (IHU) Méditerranée infection , 19-21 Boulevard Jean Moulin, 13005 Marseille, France
| | - Guillaume Blanc
- Microbiologie Environnementale Biotechnologie, Institut Méditerranéen d’Océanologie, Campus de Luminy , 163 Avenue de Luminy, 13009 Marseille, France
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Queiroz VF, Rodrigues RAL, Boratto PVDM, La Scola B, Andreani J, Abrahão JS. Amoebae: Hiding in Plain Sight: Unappreciated Hosts for the Very Large Viruses. Annu Rev Virol 2022; 9:79-98. [DOI: 10.1146/annurev-virology-100520-125832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
For decades, viruses have been isolated primarily from humans and other organisms. Interestingly, one of the most complex sides of the virosphere was discovered using free-living amoebae as hosts. The discovery of giant viruses in the early twenty-first century opened a new chapter in the field of virology. Giant viruses are included in the phylum Nucleocytoviricota and harbor large and complex DNA genomes (up to 2.7 Mb) encoding genes never before seen in the virosphere and presenting gigantic particles (up to 1.5 μm). Different amoebae have been used to isolate and characterize a plethora of new viruses with exciting details about novel viral biology. Through distinct isolation techniques and metagenomics, the diversity and complexity of giant viruses have astonished the scientific community. Here, we discuss the latest findings on amoeba viruses and how using these single-celled organisms as hosts has revealed entities that have remained hidden in plain sight for ages. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Victória Fulgêncio Queiroz
- Laboratório de Vírus, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Rodrigo Araújo Lima Rodrigues
- Laboratório de Vírus, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Bernard La Scola
- Department of Microbes, Evolution, Phylogeny and Infection, Institut de Recherche pour le Développement, Assistance Publique-Hôpitaux de Marseille, Aix-Marseille Université, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
| | - Julien Andreani
- Department of Microbes, Evolution, Phylogeny and Infection, Institut de Recherche pour le Développement, Assistance Publique-Hôpitaux de Marseille, Aix-Marseille Université, Marseille, France
- Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
- Laboratoire de Virologie, Centre Hospitalier Universitaire Grenoble-Alpes, Grenoble, France
| | - Jônatas Santos Abrahão
- Laboratório de Vírus, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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11
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del Arco A, Fischer M, Becks L. Simultaneous Giant Virus and Virophage Quantification Using Droplet Digital PCR. Viruses 2022; 14:1056. [PMID: 35632796 PMCID: PMC9144729 DOI: 10.3390/v14051056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 04/30/2022] [Accepted: 05/03/2022] [Indexed: 01/27/2023] Open
Abstract
Viruses are an abundant component of aquatic systems, but their detection and quantification remain a challenge. Virophages co-replicate with giant viruses in the shared host cell, and can inhibit the production of new giant virus particles, thereby increasing the survival of the infected host population. Here, we present a protocol for Droplet Digital PCR (ddPCR) to quantify simultaneously giant virus and virophage in a mixed sample, enabling the rapid, culture-free and high throughput detection of virus and virophage. As virophage can be present as free virus particles or integrated into the virus host's genome as well as associated with organic particles, we developed a simple method that enables discrimination between free and particle-associated virophages. The latter include aggregated virophage particles as well as virophage integrated into the host genome. We used, for our experiments, a host-virus-virophage system consisting of Cafeteria burkhardae, CroV and mavirus. Our results show that ddPCR can be an efficient method to quantify virus and virophage, and we discuss potential applications of the method for studying ecological and evolutionary processes of virus and virophages.
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Affiliation(s)
- Ana del Arco
- Limnology-Aquatic Ecology and Evolution, Limnological Institute, University of Konstanz, 78464 Konstanz, Germany;
| | - Matthias Fischer
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany;
| | - Lutz Becks
- Limnology-Aquatic Ecology and Evolution, Limnological Institute, University of Konstanz, 78464 Konstanz, Germany;
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12
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Isolation and Identification of a Large Green Alga Virus ( Chlorella Virus XW01) of Mimiviridae and Its Virophage ( Chlorella Virus Virophage SW01) by Using Unicellular Green Algal Cultures. J Virol 2022; 96:e0211421. [PMID: 35262372 DOI: 10.1128/jvi.02114-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Virophages are a group of small double-stranded DNA viruses that infect protist hosts and parasitize the viral factory of host giant/large viruses to propagate. Here, we discover a novel cell-virus-virophage (CVv) tripartite interaction system by using unicellular micro-green algae (Chlorella sp.) as eukaryotic hosts for the first time. Viral particles, resembling known virophages and large alga viruses, are detected in culture supernatants and inside algal cells. Complete genomic sequences of the virophage (Chlorella virus virophage SW01 [CVv-SW01]; 24,744 bp) and large virus (Chlorella virus XW01 [CV-XW01]; 407,612 bp) are obtained from the cocultures. Both genomic and phylogenetic analyses show that CVv-SW01 is closely related to virophages previously found in Dishui Lake. CV-XW01 shares the greatest number of homologous genes (n = 82) with Cafeteria roenbergensis virus (CroV) and phylogenetically represents the closest relative to CroV. This is the first report of a large green alga virus being affiliated with a heterotrophic zooplankton-infecting Cafeteriavirus of the family Mimiviridae. Moreover, the codon usage preferences of CV-XW01 and CVv-SW01 are highly similar to those of CroV and its virophage Mavirus, respectively. The discovery of such a novel CVv system with the green alga Chlorella sp. as the single cellular eukaryotic host paves a way to further investigate the potential interaction mechanism of CVv and its significance in the ecology of green algae and the evolution of large/giant viruses and their parasitic viruses. IMPORTANCE Parasitic virophages are small unicellular eukaryotic dsDNA viruses that rely on the viral factories of coinfecting giant/large dsDNA viruses for propagation. Presently, the identified eukaryotic hosts of isolated virophages were restricted to a free-living amoeba, Acanthamoeba polyphaga, and a widespread marine heterotrophic flagellate, Cafeteria roenbergensis. In this study, we successfully discovered and identified a novel tripartite interaction system comprised of a micro-green alga (Chlorella sp.), Mimiviridae large green alga virus, and virophage at the coculture level, with Chlorella sp. as the eukaryotic host, based on combination analysis of infection, morphotype, genome, and phylogeny. The large green alga virus CV-XW01 represents the closest relative to the Mimiviridae giant virus Cafeteria roenbergensis virus, host virus of the virophage Mavirus, as well as a novel large virus of Mimiviridae that infects a non-protozoan protist host. The virophage CVv-SW01 highly resembles Mavirus in its codon usage frequency and preference, although they are phylogenetically distantly related. These findings give novel insights into the diversity of large/giant viruses and their virophages.
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Timmons CM, Shazib SUA, Katz LA. Epigenetic influences of mobile genetic elements on ciliate genome architecture and evolution. J Eukaryot Microbiol 2022; 69:e12891. [PMID: 35100457 DOI: 10.1111/jeu.12891] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/20/2022] [Accepted: 01/22/2022] [Indexed: 11/27/2022]
Abstract
Mobile genetic elements (MGEs) are transient genetic material that can move either within a single organism's genome or between individuals or species. While historically considered 'junk' DNA (i.e. deleterious or at best neutral), more recent studies reveal the adaptive advantages MGEs provide in lineages across the tree of life. Ciliates, a group of single-celled microbial eukaryotes characterized by nuclear dimorphism, exemplify how epigenetic influences from MGEs shape genome architecture and patterns of molecular evolution. Ciliate nuclear dimorphism may have evolved as a response to transposon invasion and ciliates have since co-opted transposons to carry out programmed DNA deletion. Another example of the effect of MGEs is in providing mechanisms for lateral gene transfer from bacteria, which introduces genetic diversity and, in several cases, drives ecological specialization in ciliates. As a third example, the integration of viral DNA, likely through transduction, provides new genetic material and can change the way host cells defend themselves against other viral pathogens. We argue that the acquisition of MGEs through non-Mendelian patterns of inheritance, coupled with their effects on ciliate genome architecture and expression and persistence throughout evolutionary history, exemplify how the transmission of mobile elements should be considered a mechanism of transgenerational epigenetic inheritance.
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Affiliation(s)
- Caitlin M Timmons
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA
| | - Shahed U A Shazib
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA
| | - Laura A Katz
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01063, USA
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Irwin NAT, Pittis AA, Richards TA, Keeling PJ. Systematic evaluation of horizontal gene transfer between eukaryotes and viruses. Nat Microbiol 2021; 7:327-336. [PMID: 34972821 DOI: 10.1038/s41564-021-01026-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 11/12/2021] [Indexed: 01/19/2023]
Abstract
Gene exchange between viruses and their hosts acts as a key facilitator of horizontal gene transfer and is hypothesized to be a major driver of evolutionary change. Our understanding of this process comes primarily from bacteria and phage co-evolution, but the mode and functional importance of gene transfers between eukaryotes and their viruses remain anecdotal. Here we systematically characterized viral-eukaryotic gene exchange across eukaryotic and viral diversity, identifying thousands of transfers and revealing their frequency, taxonomic distribution and projected functions. Eukaryote-derived viral genes, abundant in the Nucleocytoviricota, highlighted common strategies for viral host-manipulation, including metabolic reprogramming, proteolytic degradation and extracellular modification. Furthermore, viral-derived eukaryotic genes implicate genetic exchange in the early evolution and diversification of eukaryotes, particularly through viral-derived glycosyltransferases, which have impacted structures as diverse as algal cell walls, trypanosome mitochondria and animal tissues. These findings illuminate the nature of viral-eukaryotic gene exchange and its impact on the evolution of viruses and their eukaryotic hosts.
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Affiliation(s)
- Nicholas A T Irwin
- Merton College, University of Oxford, Oxford, UK. .,Department of Zoology, University of Oxford, Oxford, UK. .,Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Alexandros A Pittis
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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Hackl T, Duponchel S, Barenhoff K, Weinmann A, Fischer MG. Virophages and retrotransposons colonize the genomes of a heterotrophic flagellate. eLife 2021; 10:72674. [PMID: 34698016 PMCID: PMC8547959 DOI: 10.7554/elife.72674] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 09/28/2021] [Indexed: 11/24/2022] Open
Abstract
Virophages can parasitize giant DNA viruses and may provide adaptive anti-giant virus defense in unicellular eukaryotes. Under laboratory conditions, the virophage mavirus integrates into the nuclear genome of the marine flagellate Cafeteria burkhardae and reactivates upon superinfection with the giant virus CroV. In natural systems, however, the prevalence and diversity of host-virophage associations has not been systematically explored. Here, we report dozens of integrated virophages in four globally sampled C. burkhardae strains that constitute up to 2% of their host genomes. These endogenous mavirus-like elements (EMALEs) separated into eight types based on GC-content, nucleotide similarity, and coding potential and carried diverse promoter motifs implicating interactions with different giant viruses. Between host strains, some EMALE insertion loci were conserved indicating ancient integration events, whereas the majority of insertion sites were unique to a given host strain suggesting that EMALEs are active and mobile. Furthermore, we uncovered a unique association between EMALEs and a group of tyrosine recombinase retrotransposons, revealing yet another layer of parasitism in this nested microbial system. Our findings show that virophages are widespread and dynamic in wild Cafeteria populations, supporting their potential role in antiviral defense in protists. Viruses exist in all ecosystems in vast numbers and infect many organisms. Some of them are harmful but others can protect the organisms they infect. For example, a group of viruses called virophages protect microscopic sea creatures called plankton from deadly infections by so-called giant viruses. In fact, virophages need plankton infected with giant viruses to survive because they use enzymes from the giant viruses to turn on their own genes. A virophage called mavirus integrates its genes into the DNA of a type of plankton called Cafeteria. It lays dormant in the DNA until a giant virus called CroV infects the plankton. This suggests that the mavirus may be a built-in defense against CroV infections and laboratory studies seem to confirm this. But whether wild Cafeteria also use these defenses is unknown. Hackl et al. show that virophages are common in the DNA of wild Cafeteria and that the two appear to have a mutually beneficial relationship. In the experiments, the researchers sequenced the genomes of four Cafeteria populations from the Atlantic and Pacific Oceans and looked for virophages in their DNA. Each of the four Cafeteria genomes contained dozens of virophages, which suggests that virophages are important to these plankton. This included several relatives of the mavirus and seven new virophages. Virophage genes were often interrupted by so called jumping genes, which may take advantage of the virophages the way the virophages use giant viruses to meet their own needs. The experiments show that virophages often co-exist with marine plankton from around the world and these relationships are likely beneficial. In fact, the experiments suggest that the virophages may have played an important role in the evolution of these plankton. Further studies may help scientists learn more about virus ecology and how viruses have shaped the evolution of other creatures.
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Affiliation(s)
- Thomas Hackl
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany
| | - Sarah Duponchel
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany
| | - Karina Barenhoff
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany
| | - Alexa Weinmann
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany
| | - Matthias G Fischer
- Max Planck Institute for Medical Research, Department of Biomolecular Mechanisms, Heidelberg, Germany
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Ibrahim A, Colson P, Merhej V, Zgheib R, Maatouk M, Naud S, Bittar F, Raoult D. Rhizomal Reclassification of Living Organisms. Int J Mol Sci 2021; 22:5643. [PMID: 34073251 PMCID: PMC8199106 DOI: 10.3390/ijms22115643] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/14/2021] [Accepted: 05/23/2021] [Indexed: 12/11/2022] Open
Abstract
Living organisms interact with each other during their lifetime, leading to genomes rearrangement and sequences transfer. These well-known phenomena give these organisms mosaic genomes, which challenge their classification. Moreover, many findings occurred between the IXXth and XXIst century, especially the discovery of giant viruses and candidate phyla radiation (CPR). Here, we tried to provide an updated classification, which integrates 216 representative genomes of the current described organisms. The reclassification was expressed through a genetic network based on the total genomic content, not on a single gene to represent the tree of life. This rhizomal exploration represents, more accurately, the evolutionary relationships among the studied species. Our analyses show a separated branch named fifth TRUC (Things Resisting Uncompleted Classifications). This taxon groups CPRs together, independently from Bacteria, Archaea (which regrouped also Nanoarchaeota and Asgard members), Eukarya, and the giant viruses (recognized recently as fourth TRUC). Finally, the broadening of analysis methods will lead to the discovery of new organisms, which justify the importance of updating the classification at every opportunity. In this perspective, our pragmatic representation could be adjusted along with the progress of evolutionary studies.
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Affiliation(s)
- Ahmad Ibrahim
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Philippe Colson
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Vicky Merhej
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Rita Zgheib
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, SSA, VITROME, 13005 Marseille, France
| | - Mohamad Maatouk
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Sabrina Naud
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Fadi Bittar
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
| | - Didier Raoult
- IHU Méditerranée Infection, 13005 Marseille, France; (A.I.); (P.C.); (V.M.); (R.Z.); (M.M.); (S.N.)
- Aix-Marseille Université, IRD, APHM, MEPHI, 13005 Marseille, France
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Analysis of Different Size Fractions Provides a More Complete Perspective of Viral Diversity in a Freshwater Embayment. Appl Environ Microbiol 2021; 87:AEM.00197-21. [PMID: 33741611 DOI: 10.1128/aem.00197-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/11/2021] [Indexed: 11/20/2022] Open
Abstract
Inspired by recent discoveries of the prevalence of large viruses in the environment, we reassessed the longstanding approach of filtering water through small-pore-size filters to separate viruses from cells before metagenomic analysis. We collected samples from three sites in Hamilton Harbour, an embayment of Lake Ontario, and studied 6 data sets derived from <0.45-μm- and >0.45-μm-size fractions to compare the diversity of viruses in these fractions. At the level of virus order/family, we observed highly diverse and distinct virus communities in the >0.45-μm-size fractions, whereas the <0.45-μm-size fractions were composed primarily of Caudovirales The relative abundances of Caudovirales for which hosts could be inferred varied widely between size fractions, with higher relative abundances of cyanophages in the >0.45-μm-size fractions, potentially indicating replication within cells during ongoing infections. Many viruses of eukaryotes, such as Mimiviridae, Phycodnaviridae, Iridoviridae, and Poxviridae, were detected exclusively in the often-disregarded >0.45-μm-size fractions. In addition to observing unique virus communities associated with each size fraction from every site we examined, we detected viruses common to both fractions, suggesting that these are candidates for further exploration because they could be the product of ongoing or recent lytic events. Most importantly, our observations indicate that analysis of either fraction alone provides only a partial perspective of double-stranded DNA (dsDNA) viruses in the environment, highlighting the need for more comprehensive approaches for analyzing virus communities inferred from metagenomic sequencing.IMPORTANCE Most studies of aquatic virus communities analyze DNA sequences derived from the smaller-size "free-virus" fraction. Our study demonstrates that analysis of virus communities using only the smaller-size fraction can lead to erroneously low diversity estimates for many of the larger viruses such as Mimiviridae, Phycodnaviridae, Iridoviridae, and Poxviridae, whereas analyzing only the larger->0.45-μm-size fraction can lead to underestimates of Caudovirales diversity and relative abundance. Similarly, our data show that examining only the smaller-size fraction can lead to underestimations of virophage and cyanophage relative abundances that could, in turn, cause researchers to assume their limited ecological importance. Given the considerable differences we observed in this study, we recommend cautious interpretations of environmental virus community assemblages and dynamics when based on metagenomic data derived from different size fractions.
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Aylward FO, Moniruzzaman M. ViralRecall-A Flexible Command-Line Tool for the Detection of Giant Virus Signatures in 'Omic Data. Viruses 2021; 13:v13020150. [PMID: 33498458 PMCID: PMC7909515 DOI: 10.3390/v13020150] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/07/2021] [Accepted: 01/18/2021] [Indexed: 01/06/2023] Open
Abstract
Giant viruses are widespread in the biosphere and play important roles in biogeochemical cycling and host genome evolution. Also known as nucleo-cytoplasmic large DNA viruses (NCLDVs), these eukaryotic viruses harbor the largest and most complex viral genomes known. Studies have shown that NCLDVs are frequently abundant in metagenomic datasets, and that sequences derived from these viruses can also be found endogenized in diverse eukaryotic genomes. The accurate detection of sequences derived from NCLDVs is therefore of great importance, but this task is challenging owing to both the high level of sequence divergence between NCLDV families and the extraordinarily high diversity of genes encoded in their genomes, including some encoding for metabolic or translation-related functions that are typically found only in cellular lineages. Here, we present ViralRecall, a bioinformatic tool for the identification of NCLDV signatures in ‘omic data. This tool leverages a library of giant virus orthologous groups (GVOGs) to identify sequences that bear signatures of NCLDVs. We demonstrate that this tool can effectively identify NCLDV sequences with high sensitivity and specificity. Moreover, we show that it can be useful both for removing contaminating sequences in metagenome-assembled viral genomes as well as the identification of eukaryotic genomic loci that derived from NCLDV. ViralRecall is written in Python 3.5 and is freely available on GitHub: https://github.com/faylward/viralrecall.
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Chelkha N, Levasseur A, La Scola B, Colson P. Host-virus interactions and defense mechanisms for giant viruses. Ann N Y Acad Sci 2020; 1486:39-57. [PMID: 33090482 DOI: 10.1111/nyas.14469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 06/28/2020] [Accepted: 07/26/2020] [Indexed: 12/26/2022]
Abstract
Giant viruses, with virions larger than 200 nm and genomes larger than 340 kilobase pairs, modified the now outdated perception of the virosphere. With virions now reported reaching up to 1.5 μm in size and genomes of up to 2.5 Mb encoding components shared with cellular life forms, giant viruses exhibit a complexity similar to microbes, such as bacteria and archaea. Here, we review interactions of giant viruses with their hosts and defense strategies of giant viruses against their hosts and coinfecting microorganisms or virophages. We also searched by comparative genomics for homologies with proteins described or suspected to be involved in defense mechanisms. Our search reveals that natural immunity and apoptosis seem to be crucial components of the host defense against giant virus infection. Conversely, giant viruses possess methods of hijacking host functions to counteract cellular antiviral responses. In addition, giant viruses may encode other unique and complex pathways to manipulate the host machinery and eliminate other competing microorganisms. Notably, giant viruses have evolved defense mechanisms against their virophages and they might trigger defense systems against other viruses through sequence integration. We anticipate that comparative genomics may help identifying genes involved in defense strategies of both giant viruses and their hosts.
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Affiliation(s)
- Nisrine Chelkha
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
| | - Anthony Levasseur
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
| | - Bernard La Scola
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
| | - Philippe Colson
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
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Novel Cell-Virus-Virophage Tripartite Infection Systems Discovered in the Freshwater Lake Dishui Lake in Shanghai, China. J Virol 2020; 94:JVI.00149-20. [PMID: 32188734 DOI: 10.1128/jvi.00149-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 03/12/2020] [Indexed: 01/30/2023] Open
Abstract
Virophages are small parasitic double-stranded DNA (dsDNA) viruses of giant dsDNA viruses infecting unicellular eukaryotes. Except for a few isolated virophages characterized by parasitization mechanisms, features of virophages discovered in metagenomic data sets remain largely unknown. Here, the complete genomes of seven virophages (26.6 to 31.5 kbp) and four large DNA viruses (190.4 to 392.5 kbp) that coexist in the freshwater lake Dishui Lake, Shanghai, China, have been identified based on environmental metagenomic investigation. Both genomic and phylogenetic analyses indicate that Dishui Lake virophages (DSLVs) are closely related to each other and to other lake virophages, and Dishui Lake large DNA viruses are affiliated with the micro-green alga-infecting Prasinovirus of the Phycodnaviridae (named Dishui Lake phycodnaviruses [DSLPVs]) and protist (protozoan and alga)-infecting Mimiviridae (named Dishui Lake large alga virus [DSLLAV]). The DSLVs possess more genes with closer homology to that of large alga viruses than to that of giant protozoan viruses. Furthermore, the DSLVs are strongly associated with large green alga viruses, including DSLPV4 and DSLLAV1, based on codon usage as well as oligonucleotide frequency and correlation analyses. Surprisingly, a nonhomologous CRISPR-Cas like system is found in DSLLAV1, which appears to protect DSLLAV1 from the parasitization of DSLV5 and DSLV8. These results suggest that novel cell-virus-virophage (CVv) tripartite infection systems of green algae, large green alga virus (Phycodnaviridae- and Mimiviridae-related), and virophage exist in Dishui Lake, which will contribute to further deep investigations of the evolutionary interaction of virophages and large alga viruses as well as of the essential roles that the CVv plays in the ecology of algae.IMPORTANCE Virophages are small parasitizing viruses of large/giant viruses. To our knowledge, the few isolated virophages all parasitize giant protozoan viruses (Mimiviridae) for propagation and form a tripartite infection system with hosts, here named the cell-virus-virophage (CVv) system. However, the CVv system remains largely unknown in environmental metagenomic data sets. In this study, we systematically investigated the metagenomic data set from the freshwater lake Dishui Lake, Shanghai, China. Consequently, four novel large alga viruses and seven virophages were discovered to coexist in Dishui Lake. Surprisingly, a novel CVv tripartite infection system comprising green algae, large green alga viruses (Phycodnaviridae- and Mimiviridae-related), and virophages was identified based on genetic link, genomic signature, and CRISPR system analyses. Meanwhile, a nonhomologous CRISPR-like system was found in Dishui Lake large alga viruses, which appears to protect the virus host from the infection of Dishui Lake virophages (DSLVs). These findings are critical to give insight into the potential significance of CVv in global evolution and ecology.
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Paez-Espino D, Zhou J, Roux S, Nayfach S, Pavlopoulos GA, Schulz F, McMahon KD, Walsh D, Woyke T, Ivanova NN, Eloe-Fadrosh EA, Tringe SG, Kyrpides NC. Diversity, evolution, and classification of virophages uncovered through global metagenomics. MICROBIOME 2019; 7:157. [PMID: 31823797 PMCID: PMC6905037 DOI: 10.1186/s40168-019-0768-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/11/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND Virophages are small viruses with double-stranded DNA genomes that replicate along with giant viruses and co-infect eukaryotic cells. Due to the paucity of virophage reference genomes, a collective understanding of the global virophage diversity, distribution, and evolution is lacking. RESULTS Here we screened a public collection of over 14,000 metagenomes using the virophage-specific major capsid protein (MCP) as "bait." We identified 44,221 assembled virophage sequences, of which 328 represent high-quality (complete or near-complete) genomes from diverse habitats including the human gut, plant rhizosphere, and terrestrial subsurface. Comparative genomic analysis confirmed the presence of four core genes in a conserved block. We used these genes to establish a revised virophage classification including 27 clades with consistent genome length, gene content, and habitat distribution. Moreover, for eight high-quality virophage genomes, we computationally predicted putative eukaryotic virus hosts. CONCLUSION Overall, our approach has increased the number of known virophage genomes by 10-fold and revealed patterns of genome evolution and global virophage distribution. We anticipate that the expanded diversity presented here will provide the backbone for further virophage studies.
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Affiliation(s)
- David Paez-Espino
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Jinglie Zhou
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Simon Roux
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Stephen Nayfach
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Georgios A. Pavlopoulos
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
- BSRC “Alexander Fleming”, 34 Fleming Street, Vari, 16672 Athens, Greece
| | - Frederik Schulz
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Katherine D. McMahon
- Departments of Civil and Environmental Engineering and Bacteriology, University of Wisconsin Madison, 1550 Linden Drive, Madison, WI 53726 USA
| | - David Walsh
- Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, QC, H4B 1R6 Canada
| | - Tanja Woyke
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Natalia N. Ivanova
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Emiley A. Eloe-Fadrosh
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Susannah G. Tringe
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
| | - Nikos C. Kyrpides
- Department of Energy, Joint Genome Institute, 2800 Mitchell Dr., Walnut Creek, 94598 USA
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Abstract
Since the discovery of mimivirus, numerous giant viruses associated with free-living amoebae have been described. The genome of giant viruses can be more than 2.5 megabases, and virus particles can exceed the size of many bacteria. The unexpected characteristics of these viruses have made them intriguing research targets and, as a result, studies focusing on their interactions with their amoeba host have gained increased attention. Studies have shown that giant viruses can establish host-pathogen interactions, which have not been previously demonstrated, including the unprecedented interaction with a new group of small viruses, called virophages, that parasitize their viral factories. In this brief review, we present recent advances in virophage-giant virus-host interactions and highlight selected studies involving interactions between giant viruses and amoebae. These unprecedented interactions involve the giant viruses mimivirus, marseillevirus, tupanviruses and faustovirus, all of which modulate the amoeba environment, affecting both their replication and their spread to new hosts.
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Koonin EV, Makarova KS, Wolf YI, Krupovic M. Evolutionary entanglement of mobile genetic elements and host defence systems: guns for hire. Nat Rev Genet 2019; 21:119-131. [PMID: 31611667 DOI: 10.1038/s41576-019-0172-9] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2019] [Indexed: 12/12/2022]
Abstract
All cellular life forms are afflicted by diverse genetic parasites, including viruses and other types of mobile genetic elements (MGEs), and have evolved multiple, diverse defence systems that protect them from MGE assault via different mechanisms. Here, we provide our perspectives on how recent evidence points to tight evolutionary connections between MGEs and defence systems that reach far beyond the proverbial arms race. Defence systems incur a fitness cost for the hosts; therefore, at least in prokaryotes, horizontal mobility of defence systems, mediated primarily by MGEs, is essential for their persistence. Moreover, defence systems themselves possess certain features of selfish elements. Common components of MGEs, such as site-specific nucleases, are 'guns for hire' that can also function as parts of defence mechanisms and are often shuttled between MGEs and defence systems. Thus, evolutionary and molecular factors converge to mould the multifaceted, inextricable connection between MGEs and anti-MGE defence systems.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA.
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, USA
| | - Mart Krupovic
- Department of Microbiology, Institut Pasteur, Paris, France.
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Castillo YM, Mangot J, Benites LF, Logares R, Kuronishi M, Ogata H, Jaillon O, Massana R, Sebastián M, Vaqué D. Assessing the viral content of uncultured picoeukaryotes in the global‐ocean by single cell genomics. Mol Ecol 2019; 28:4272-4289. [DOI: 10.1111/mec.15210] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 07/23/2019] [Accepted: 08/01/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Yaiza M. Castillo
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
| | - Jean‐François Mangot
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
| | - Luiz Felipe Benites
- Integrative Biology of Marine Organisms (BIOM) CNRS Oceanological Observatory of Banyuls Sorbonne University Banyuls‐sur‐Mer France
| | - Ramiro Logares
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
| | - Megumi Kuronishi
- Bioinformatic Center Institute for Chemical Research Kyoto University Uji Japan
| | - Hiroyuki Ogata
- Bioinformatic Center Institute for Chemical Research Kyoto University Uji Japan
| | - Olivier Jaillon
- Génomique Métabolique Genoscope Institut de biologie François Jacob CEA CNRS Université d'Evry Université Paris‐Saclay Evry France
| | - Ramon Massana
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
| | - Marta Sebastián
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
- Institute of Oceanography and Global Change (IOCAG) University of Las Palmas de Gran Canaria Telde Spain
| | - Dolors Vaqué
- Department of Marine Biology and Oceanography Institute of Marine Sciences (ICM) CSIC Barcelona Spain
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Effects on Gene Transcription Profile and Fatty Acid Composition by Genetic Modification of Mevalonate Diphosphate Decarboxylase MVD/Erg19 in Aspergillus Oryzae. Microorganisms 2019; 7:microorganisms7090342. [PMID: 31514444 PMCID: PMC6780523 DOI: 10.3390/microorganisms7090342] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/03/2019] [Accepted: 09/08/2019] [Indexed: 12/30/2022] Open
Abstract
Mevalonate diphosphate decarboxylase MVD/Erg19 is required for ergosterol biosynthesis, growth, sporulation, and stress tolerance in Aspergillus oryzae. In this study, RNA-seq was used to analyze the gene transcription profile in AoErg19 overexpression (OE) and RNAi strains. There were 256 and 74 differentially expressed genes (DEGs) in AoErg19 OE and RNAi strains, respectively, compared with the control strain (CK). The most common DEGs were transport- and metabolism-related genes. Only 22 DEGs were obtained that were regulated in both OE and RNAi strains. The transcriptomic comparison between CK and AoErg19 overexpression strain (CK vs. OE), and between CK and AoErg19 RNAi strain (CK vs. RNAi) revealed that the greatest difference existed in the number of genes belonging to the cytochrome P450 family; 12 were found in CK vs. OE, whereas 1 was found in CK vs. RNAi. The expression patterns of lipid biosynthesis and metabolism related genes were altered in OE and RNAi strains, either by gene induction or suppression. Moreover, the total fatty acid content in the RNAi strain was 12.1% greater than the control strain, but no difference in total acid content was found between the overexpression strain and the control strain. Therefore, this study highlights the gene expression regulation within mevalonate (MVA), ergosterol biosynthesis, and fatty acid biosynthesis pathways.
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Mougari S, Sahmi-Bounsiar D, Levasseur A, Colson P, La Scola B. Virophages of Giant Viruses: An Update at Eleven. Viruses 2019; 11:E733. [PMID: 31398856 PMCID: PMC6723459 DOI: 10.3390/v11080733] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 12/19/2022] Open
Abstract
The last decade has been marked by two eminent discoveries that have changed our perception of the virology field: The discovery of giant viruses and a distinct new class of viral agents that parasitize their viral factories, the virophages. Coculture and metagenomics have actively contributed to the expansion of the virophage family by isolating dozens of new members. This increase in the body of data on virophage not only revealed the diversity of the virophage group, but also the relevant ecological impact of these small viruses and their potential role in the dynamics of the microbial network. In addition, the isolation of virophages has led us to discover previously unknown features displayed by their host viruses and cells. In this review, we present an update of all the knowledge on the isolation, biology, genomics, and morphological features of the virophages, a decade after the discovery of their first member, the Sputnik virophage. We discuss their parasitic lifestyle as bona fide viruses of the giant virus factories, genetic parasites of their genomes, and then their role as a key component or target for some host defense mechanisms during the tripartite virophage-giant virus-host cell interaction. We also present the latest advances regarding their origin, classification, and definition that have been widely discussed.
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Affiliation(s)
- Said Mougari
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), 27 boulevard Jean Moulin, 13005 Marseille, France
- Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France
| | - Dehia Sahmi-Bounsiar
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), 27 boulevard Jean Moulin, 13005 Marseille, France
- Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France
| | - Anthony Levasseur
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), 27 boulevard Jean Moulin, 13005 Marseille, France
- Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France
| | - Philippe Colson
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), 27 boulevard Jean Moulin, 13005 Marseille, France.
- Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France.
| | - Bernard La Scola
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), 27 boulevard Jean Moulin, 13005 Marseille, France.
- Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France.
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Armaleo D, Müller O, Lutzoni F, Andrésson ÓS, Blanc G, Bode HB, Collart FR, Dal Grande F, Dietrich F, Grigoriev IV, Joneson S, Kuo A, Larsen PE, Logsdon JM, Lopez D, Martin F, May SP, McDonald TR, Merchant SS, Miao V, Morin E, Oono R, Pellegrini M, Rubinstein N, Sanchez-Puerta MV, Savelkoul E, Schmitt I, Slot JC, Soanes D, Szövényi P, Talbot NJ, Veneault-Fourrey C, Xavier BB. The lichen symbiosis re-viewed through the genomes of Cladonia grayi and its algal partner Asterochloris glomerata. BMC Genomics 2019; 20:605. [PMID: 31337355 PMCID: PMC6652019 DOI: 10.1186/s12864-019-5629-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 03/20/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Lichens, encompassing 20,000 known species, are symbioses between specialized fungi (mycobionts), mostly ascomycetes, and unicellular green algae or cyanobacteria (photobionts). Here we describe the first parallel genomic analysis of the mycobiont Cladonia grayi and of its green algal photobiont Asterochloris glomerata. We focus on genes/predicted proteins of potential symbiotic significance, sought by surveying proteins differentially activated during early stages of mycobiont and photobiont interaction in coculture, expanded or contracted protein families, and proteins with differential rates of evolution. RESULTS A) In coculture, the fungus upregulated small secreted proteins, membrane transport proteins, signal transduction components, extracellular hydrolases and, notably, a ribitol transporter and an ammonium transporter, and the alga activated DNA metabolism, signal transduction, and expression of flagellar components. B) Expanded fungal protein families include heterokaryon incompatibility proteins, polyketide synthases, and a unique set of G-protein α subunit paralogs. Expanded algal protein families include carbohydrate active enzymes and a specific subclass of cytoplasmic carbonic anhydrases. The alga also appears to have acquired by horizontal gene transfer from prokaryotes novel archaeal ATPases and Desiccation-Related Proteins. Expanded in both symbionts are signal transduction components, ankyrin domain proteins and transcription factors involved in chromatin remodeling and stress responses. The fungal transportome is contracted, as are algal nitrate assimilation genes. C) In the mycobiont, slow-evolving proteins were enriched for components involved in protein translation, translocation and sorting. CONCLUSIONS The surveyed genes affect stress resistance, signaling, genome reprogramming, nutritional and structural interactions. The alga carries many genes likely transferred horizontally through viruses, yet we found no evidence of inter-symbiont gene transfer. The presence in the photobiont of meiosis-specific genes supports the notion that sexual reproduction occurs in Asterochloris while they are free-living, a phenomenon with implications for the adaptability of lichens and the persistent autonomy of the symbionts. The diversity of the genes affecting the symbiosis suggests that lichens evolved by accretion of many scattered regulatory and structural changes rather than through introduction of a few key innovations. This predicts that paths to lichenization were variable in different phyla, which is consistent with the emerging consensus that ascolichens could have had a few independent origins.
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Affiliation(s)
| | - Olaf Müller
- Department of Biology, Duke University, Durham, USA
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, USA
| | | | - Ólafur S. Andrésson
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
| | - Guillaume Blanc
- Aix Marseille University, Université de Toulon, CNRS, IRD, MIO UM 110, 13288 Marseille, France
| | - Helge B. Bode
- Molekulare Biotechnologie, Fachbereich Biowissenschaften & Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Frank R. Collart
- Argonne National Laboratory, Biosciences Division, Argonne, & Department of Bioengineering, University of Illinois at Chicago, Chicago, USA
| | - Francesco Dal Grande
- Senckenberg Biodiversity and Climate Research Center (SBiK-F), Frankfurt am Main, Germany
| | - Fred Dietrich
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, USA
| | - Igor V. Grigoriev
- US Department of Energy Joint Genome Institute, Walnut Creek, USA
- Department of Plant and Microbial Biology, University of California – Berkeley, Berkeley, USA
| | - Suzanne Joneson
- Department of Biology, Duke University, Durham, USA
- College of General Studies, University of Wisconsin - Milwaukee at Waukesha, Waukesha, USA
| | - Alan Kuo
- US Department of Energy Joint Genome Institute, Walnut Creek, USA
| | - Peter E. Larsen
- Argonne National Laboratory, Biosciences Division, Argonne, & Department of Bioengineering, University of Illinois at Chicago, Chicago, USA
| | | | | | - Francis Martin
- INRA, Université de Lorraine, Interactions Arbres-Microorganismes, INRA-Nancy, Champenoux, France
| | - Susan P. May
- Department of Biology, Duke University, Durham, USA
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, USA
| | - Tami R. McDonald
- Department of Biology, Duke University, Durham, USA
- Department of Biology, St. Catherine University, St. Paul, USA
| | - Sabeeha S. Merchant
- Department of Plant and Microbial Biology, University of California – Berkeley, Berkeley, USA
- Department of Molecular and Cell Biology, University of California – Berkeley, Berkeley, USA
| | - Vivian Miao
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Emmanuelle Morin
- INRA, Université de Lorraine, Interactions Arbres-Microorganismes, INRA-Nancy, Champenoux, France
| | - Ryoko Oono
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell, and Developmental Biology, and DOE Institute for Genomics and Proteomics, University of California, Los Angeles, USA
| | - Nimrod Rubinstein
- National Evolutionary Synthesis Center, Durham, USA
- Calico Life Sciences LLC, South San Francisco, USA
| | | | | | - Imke Schmitt
- Senckenberg Biodiversity and Climate Research Center (SBiK-F), Frankfurt am Main, Germany
- Institute of Ecology, Evolution and Diversity, Fachbereich Biowissenschaften, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jason C. Slot
- College of Food, Agricultural, and Environmental Sciences, Department of Plant Pathology, The Ohio State University, Columbus, USA
| | - Darren Soanes
- College of Life & Environmental Sciences, University of Exeter, Exeter, UK
| | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland
| | | | - Claire Veneault-Fourrey
- INRA, Université de Lorraine, Interactions Arbres-Microorganismes, INRA-Nancy, Champenoux, France
- Université de Lorraine, INRA, Interactions Arbres-Microorganismes, Faculté des Sciences et Technologies, Vandoeuvre les Nancy Cedex, France
| | - Basil B. Xavier
- Faculty of Life and Environmental Sciences, University of Iceland, Reykjavík, Iceland
- Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
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Berjón-Otero M, Koslová A, Fischer MG. The dual lifestyle of genome-integrating virophages in protists. Ann N Y Acad Sci 2019; 1447:97-109. [PMID: 31162694 DOI: 10.1111/nyas.14118] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/15/2019] [Accepted: 04/21/2019] [Indexed: 01/03/2023]
Abstract
DNA viruses with efficient host genome integration capability were unknown in eukaryotes until recently. The discovery of virophages, satellite-like DNA viruses that depend on lytic giant viruses that infect protists, revealed a genetically diverse group of viruses with high genome mobility. Virophages can act as strong inhibitors of their associated giant viruses, and the resulting beneficial effects on their unicellular hosts resemble a population-based antiviral defense mechanism. By comparing various aspects of genome-integrating virophages, in particular the virophage mavirus, with other mobile genetic elements and parasite-derived defense mechanisms in eukaryotes and prokaryotes, we show that virophages share many features with other host-parasite systems. Yet, the dual lifestyle exhibited by mavirus remains unprecedented among eukaryotic DNA viruses, with potentially far-reaching ecological and evolutionary consequences for the host.
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Affiliation(s)
- Mónica Berjón-Otero
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Anna Koslová
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Matthias G Fischer
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
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Medusavirus, a Novel Large DNA Virus Discovered from Hot Spring Water. J Virol 2019; 93:JVI.02130-18. [PMID: 30728258 PMCID: PMC6450098 DOI: 10.1128/jvi.02130-18] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/24/2019] [Indexed: 12/22/2022] Open
Abstract
Recent discoveries of new large DNA viruses reveal high diversity in their morphologies, genetic repertoires, and replication strategies. Here, we report the novel features of medusavirus, a large DNA virus newly isolated from hot spring water in Japan. Medusavirus, with a diameter of 260 nm, shows a T=277 icosahedral capsid with unique spherical-headed spikes on its surface. It has a 381-kb genome encoding 461 putative proteins, 86 of which have their closest homologs in Acanthamoeba, whereas 279 (61%) are orphan genes. The virus lacks the genes encoding DNA topoisomerase II and RNA polymerase, showing that DNA replication takes place in the host nucleus, whereas the progeny virions are assembled in the cytoplasm. Furthermore, the medusavirus genome harbored genes for all five types of histones (H1, H2A, H2B, H3, and H4) and one DNA polymerase, which are phylogenetically placed at the root of the eukaryotic clades. In contrast, the host amoeba encoded many medusavirus homologs, including the major capsid protein. These facts strongly suggested that amoebae are indeed the most promising natural hosts of medusavirus, and that lateral gene transfers have taken place repeatedly and bidirectionally between the virus and its host since the early stage of their coevolution. Medusavirus reflects the traces of direct evolutionary interactions between the virus and eukaryotic hosts, which may be caused by sharing the DNA replication compartment and by evolutionarily long lasting virus-host relationships. Based on its unique morphological characteristics and phylogenomic relationships with other known large DNA viruses, we propose that medusavirus represents a new family, Medusaviridae IMPORTANCE We have isolated a new nucleocytoplasmic large DNA virus (NCLDV) from hot spring water in Japan, named medusavirus. This new NCLDV is phylogenetically placed at the root of the eukaryotic clades based on the phylogenies of several key genes, including that encoding DNA polymerase, and its genome surprisingly encodes the full set of histone homologs. Furthermore, its laboratory host, Acanthamoeba castellanii, encodes many medusavirus homologs in its genome, including the major capsid protein, suggesting that the amoeba is the genuine natural host from ancient times of this newly described virus and that lateral gene transfers have repeatedly occurred between the virus and amoeba. These results suggest that medusavirus is a unique NCLDV preserving ancient footprints of evolutionary interactions with its hosts, thus providing clues to elucidate the evolution of NCLDVs, eukaryotes, and virus-host interaction. Based on the dissimilarities with other known NCLDVs, we propose that medusavirus represents a new viral family, Medusaviridae.
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Duponchel S, Fischer MG. Viva lavidaviruses! Five features of virophages that parasitize giant DNA viruses. PLoS Pathog 2019; 15:e1007592. [PMID: 30897185 PMCID: PMC6428243 DOI: 10.1371/journal.ppat.1007592] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Sarah Duponchel
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Matthias G. Fischer
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
- * E-mail:
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31
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Hu Z, Li G, Sun Y, Niu Y, Ma L, He B, Ai M, Han J, Zeng B. Gene transcription profiling of Aspergillus oryzae 3.042 treated with ergosterol biosynthesis inhibitors. Braz J Microbiol 2019; 50:43-52. [PMID: 30637636 PMCID: PMC6863321 DOI: 10.1007/s42770-018-0026-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 10/04/2018] [Indexed: 01/05/2023] Open
Abstract
Ergosterol, a unique component of fungal cells, is not only important for fungal growth and stress responses but also holds great economic value. Limited studies have been performed on ergosterol biosynthesis in Aspergillus oryzae, a safe filamentous fungus that has been used for the manufacture of oriental fermented foods. This study revealed that the ergosterol biosynthesis pathway is conserved between Saccharomyces cerevisiae and A. oryzae 3.042 by treatment with ergosterol biosynthesis inhibitors and bioinformatics analysis. However, the ergosterol biosynthesis pathway in A. oryzae 3.042 is more complicated than that in S. cerevisiae as there are multiple paralogs encoding the same biosynthetic enzymes. Using RNA-seq, this study identified 138 and 104 differentially expressed genes (DEG) in response to the ergosterol biosynthesis inhibitors tebuconazole and terbinafine, respectively. The results showed that the most common DEGs were transport- and metabolism-related genes. There were only 17 DEGs regulated by both tebuconazole and terbinafine treatments and there were 256 DEGs between tebuconazole and terbinafine treatments. These results provide new information on A. oryzae ergosterol biosynthesis and regulation mechanisms, which may lay the foundation for genetic modification of the ergosterol biosynthesis pathway in A. oryzae.
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Affiliation(s)
- Zhihong Hu
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Ganghua Li
- Hubei Key Laboratory of Edible Wild Plants Conservation and Utilization, Hubei Normal University, Huangshi, 435002, China
| | - Yunlong Sun
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Yali Niu
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Long Ma
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Bin He
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Mingqiang Ai
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Jizhong Han
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China
| | - Bin Zeng
- Jiangxi Key Laboratory of Bioprocess Engineering and Co-Innovation Center for In-vitro Diagnostic Reagents and Devices of Jiangxi Province, college of life sciences, Jiangxi Science & Technology Normal University, Nanchang, 330013, China.
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Colson P, Ominami Y, Hisada A, La Scola B, Raoult D. Giant mimiviruses escape many canonical criteria of the virus definition. Clin Microbiol Infect 2018; 25:147-154. [PMID: 30267933 DOI: 10.1016/j.cmi.2018.09.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/05/2018] [Accepted: 09/10/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND The discovery of mimivirus in 2003 prompted the quest for other giant viruses of amoebae. Mimiviruses and their relatives were found to differ considerably from other viruses. Their study led to major advances in virology and evolutionary biology. AIMS We summarized the widening gap between mimiviruses and other viruses. SOURCES We collected data from articles retrieved from PubMed using as keywords 'giant virus', 'mimivirus' and 'virophage', as well as quoted references from these articles. CONTENT Data accumulated during the last 15 years on mimiviruses and other giant viruses highlight that there is a quantum leap between these infectious agents, the complexity of which is similar to that of intracellular microorganisms, and classical viruses. Notably, in addition to their giant structures and genomes, giant viruses have abundant gene repertoires with genes unique in the virosphere, including a tremendous set of translation components. The viruses contain hundreds of proteins and many transcripts. They share a core of central and ancient proteins but their genome sequences display a substantial level of mosaicism. Finally, mimiviruses have a specific mobilome, including virophages that can integrate into their genomes, and against which they can defend themselves through integration of short fragments of the DNA of these invaders. IMPLICATIONS Mimiviruses and subsequently discovered giant viruses have changed the virus paradigm and contradict many virus definition criteria delineated for classical viruses. The major cellular hallmark that is still lacking in giant viruses is the ribosome, including both ribosomal protein and RNA encoding genes, which makes them bona fide microbes without ribosomes.
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Affiliation(s)
- P Colson
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM); Microbes, Evolution, Phylogeny and Infection (MEΦI); Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France
| | - Y Ominami
- Hitachi High-Technologies Corporation, Science & Medical Systems Business Group, Minato-ku, Tokyo, Japan
| | - A Hisada
- Hitachi Ltd, Research & Development Group, Saitama, Japan
| | - B La Scola
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM); Microbes, Evolution, Phylogeny and Infection (MEΦI); Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France
| | - D Raoult
- Aix-Marseille Université, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM); Microbes, Evolution, Phylogeny and Infection (MEΦI); Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, 19-21 boulevard Jean Moulin, 13005 Marseille, France.
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Chelkha N, Levasseur A, Pontarotti P, Raoult D, Scola BL, Colson P. A Phylogenomic Study of Acanthamoeba polyphaga Draft Genome Sequences Suggests Genetic Exchanges With Giant Viruses. Front Microbiol 2018; 9:2098. [PMID: 30237791 PMCID: PMC6135880 DOI: 10.3389/fmicb.2018.02098] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/16/2018] [Indexed: 11/18/2022] Open
Abstract
Acanthamoeba are ubiquitous phagocytes predominant in soil and water which can ingest many microbes. Giant viruses of amoebae are listed among the Acanthamoeba-resisting microorganisms. Their sympatric lifestyle within amoebae is suspected to promote lateral nucleotide sequence transfers. Some Acanthamoeba species have shown differences in their susceptibility to giant viruses. Until recently, only the genome of a single Acanthamoeba castellanii Neff was available. We analyzed the draft genome sequences of Acanthamoeba polyphaga through several approaches, including comparative genomics, phylogeny, and sequence networks, with the aim of detecting putative nucleotide sequence exchanges with giant viruses. We identified a putative sequence trafficking between this Acanthamoeba species and giant viruses, with 366 genes best matching with viral genes. Among viruses, Pandoraviruses provided the greatest number of best hits with 117 (32%) for A. polyphaga. Then, genes from mimiviruses, Mollivirus sibericum, marseilleviruses, and Pithovirus sibericum were best hits in 67 (18%), 35 (9%), 24 (7%), and 2 (0.5%) cases, respectively. Phylogenetic reconstructions showed in a few cases that the most parsimonious evolutionary scenarios were a transfer of gene sequences from giant viruses to A. polyphaga. Nevertheless, in most cases, phylogenies were inconclusive regarding the sense of the sequence flow. The number and nature of putative nucleotide sequence transfers between A. polyphaga, and A. castellanii ATCC 50370 on the one hand, and pandoraviruses, mimiviruses and marseilleviruses on the other hand were analyzed. The results showed a lower number of differences within the same giant viral family compared to between different giant virus families. The evolution of 10 scaffolds that were identified among the 14 Acanthamoeba sp. draft genome sequences and that harbored ≥ 3 genes best matching with viruses showed a conservation of these scaffolds and their 46 viral genes in A. polyphaga, A. castellanii ATCC 50370 and A. pearcei. In contrast, the number of conserved genes decreased for other Acanthamoeba species, and none of these 46 genes were present in three of them. Overall, this work opens up several potential avenues for future studies on the interactions between Acanthamoeba species and giant viruses.
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Affiliation(s)
- Nisrine Chelkha
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
| | - Anthony Levasseur
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
| | - Pierre Pontarotti
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
| | - Didier Raoult
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
| | - Bernard La Scola
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
| | - Philippe Colson
- Institut de Recherche pour le Développement, Assistance Publique - Hôpitaux de Marseille, Microbes, Evolution, Phylogeny and Infection, and Institut Hospitalo-Universitaire - Méditerranée Infection, Aix-Marseille Université, Marseille, France
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Koonin EV, Krupovic M. The depths of virus exaptation. Curr Opin Virol 2018; 31:1-8. [PMID: 30071360 DOI: 10.1016/j.coviro.2018.07.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/13/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023]
Abstract
Viruses are ubiquitous parasites of cellular life forms and the most abundant biological entities on earth. The relationships between viruses and their hosts involve the continuous arms race but are by no account limited to it. Growing evidence shows that, in the course of evolution, viruses and their components are repeatedly recruited (exapted) for host functions. The functions of exapted viruses typically involve either defense from other viruses or cellular competitors or transfer of nucleic acids between cells, or storage functions. Virus exaptation can reach different depths, from recruitment of a fully functional virus to exploitation of defective, partially degraded viruses, to utilization of individual virus proteins.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, United States.
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, 25 rue du Docteur Roux, Paris 75015, France.
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Capsid protein structure, self-assembly, and processing reveal morphogenesis of the marine virophage mavirus. Proc Natl Acad Sci U S A 2018; 115:7332-7337. [PMID: 29941605 PMCID: PMC6048507 DOI: 10.1073/pnas.1805376115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Virophages have the unique property of parasitizing giant viruses within unicellular hosts. Little is understood about how they form infectious virions in this tripartite interplay. We provide mechanistic insights into assembly and maturation of mavirus, a marine virophage, by combining structural and stability studies on capsomers, virus-like particles (VLPs), and native virions. We found that the mavirus protease processes the double jelly-roll (DJR) major capsid protein (MCP) at multiple C-terminal sites and that these sites are conserved among virophages. Mavirus MCP assembled in Escherichia coli in the absence and presence of penton protein, forming VLPs with defined size and shape. While quantifying VLPs in E. coli lysates, we found that full-length rather than processed MCP is the competent state for capsid assembly. Full-length MCP was thermally more labile than truncated MCP, and crystal structures of both states indicate that full-length MCP has an expanded DJR core. Thus, we propose that the MCP C-terminal domain serves as a scaffolding domain by adding strain on MCP to confer assembly competence. Mavirus protease processed MCP more efficiently after capsid assembly, which provides a regulation mechanism for timing capsid maturation. By analogy to Sputnik and adenovirus, we propose that MCP processing renders mavirus particles infection competent by loosening interactions between genome and capsid shell and destabilizing pentons for genome release into host cells. The high structural similarity of mavirus and Sputnik capsid proteins together with conservation of protease and MCP processing suggest that assembly and maturation mechanisms described here are universal for virophages.
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36
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Grybchuk D, Kostygov AY, Macedo DH, d'Avila-Levy CM, Yurchenko V. RNA viruses in trypanosomatid parasites: a historical overview. Mem Inst Oswaldo Cruz 2018. [PMID: 29513877 PMCID: PMC5851034 DOI: 10.1590/0074-02760170487] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Viruses of trypanosomatids are now being extensively studied because of their diversity and the roles they play in flagellates' biology. Among the most prominent examples are leishmaniaviruses implicated in pathogenesis of Leishmania parasites. Here, we present a historical overview of this field, starting with early reports of virus-like particles on electron microphotographs, and culminating in detailed molecular descriptions of viruses obtained using modern next generation sequencing-based techniques. Because of their diversity, different life cycle strategies and host specificity, we believe that trypanosomatids are a fertile ground for further explorations to better understand viral evolution, routes of transitions, and molecular mechanisms of adaptation to different hosts.
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Affiliation(s)
- Danyil Grybchuk
- University of Ostrava, Faculty of Science, Life Science Research Centre, Ostrava, Czech Republic
| | - Alexei Y Kostygov
- University of Ostrava, Faculty of Science, Life Science Research Centre, Ostrava, Czech Republic
| | - Diego H Macedo
- University of Ostrava, Faculty of Science, Life Science Research Centre, Ostrava, Czech Republic
| | - Claudia M d'Avila-Levy
- Fundação Oswaldo Cruz-Fiocruz, Instituto Oswaldo Cruz, Laboratório de Estudos Integrados em Protozoologia, Coleção de Protozoários, Rio de Janeiro, RJ, Brasil
| | - Vyacheslav Yurchenko
- University of Ostrava, Faculty of Science, Life Science Research Centre, Ostrava, Czech Republic
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Diesend J, Kruse J, Hagedorn M, Hammann C. Amoebae, Giant Viruses, and Virophages Make Up a Complex, Multilayered Threesome. Front Cell Infect Microbiol 2018; 7:527. [PMID: 29376032 PMCID: PMC5768912 DOI: 10.3389/fcimb.2017.00527] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 12/13/2017] [Indexed: 01/28/2023] Open
Abstract
Viral infection had not been observed for amoebae, until the Acanthamoeba polyphaga mimivirus (APMV) was discovered in 2003. APMV belongs to the nucleocytoplasmatic large DNA virus (NCLDV) family and infects not only A. polyphaga, but also other professional phagocytes. Here, we review the Megavirales to give an overview of the current members of the Mimi- and Marseilleviridae families and their structural features during amoebal infection. We summarize the different steps of their infection cycle in A. polyphaga and Acanthamoeba castellani. Furthermore, we dive into the emerging field of virophages, which parasitize upon viral factories of the Megavirales family. The discovery of virophages in 2008 and research in recent years revealed an increasingly complex network of interactions between cell, giant virus, and virophage. Virophages seem to be highly abundant in the environment and occupy the same niches as the Mimiviridae and their hosts. Establishment of metagenomic and co-culture approaches rapidly increased the number of detected virophages over the recent years. Genetic interaction of cell and virophage might constitute a potent defense machinery against giant viruses and seems to be important for survival of the infected cell during mimivirus infections. Nonetheless, the molecular events during co-infection and the interactions of cell, giant virus, and virophage have not been elucidated, yet. However, the genetic interactions of these three, suggest an intricate, multilayered network during amoebal (co-)infections. Understanding these interactions could elucidate molecular events essential for proper viral factory activity and could implicate new ways of treating viruses that form viral factories.
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Affiliation(s)
- Jan Diesend
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Janis Kruse
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Monica Hagedorn
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Christian Hammann
- Ribogenetics Biochemistry Lab, Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
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38
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Complete fusion of a transposon and herpesvirus created the Teratorn mobile element in medaka fish. Nat Commun 2017; 8:551. [PMID: 28916771 PMCID: PMC5601938 DOI: 10.1038/s41467-017-00527-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 07/05/2017] [Indexed: 01/02/2023] Open
Abstract
Mobile genetic elements (e.g., transposable elements and viruses) display significant diversity with various life cycles, but how novel elements emerge remains obscure. Here, we report a giant (180-kb long) transposon, Teratorn, originally identified in the genome of medaka, Oryzias latipes. Teratorn belongs to the piggyBac superfamily and retains the transposition activity. Remarkably, Teratorn is largely derived from a herpesvirus of the Alloherpesviridae family that could infect fish and amphibians. Genomic survey of Teratorn-like elements reveals that some of them exist as a fused form between piggyBac transposon and herpesvirus genome in teleosts, implying the generality of transposon-herpesvirus fusion. We propose that Teratorn was created by a unique fusion of DNA transposon and herpesvirus, leading to life cycle shift. Our study supports the idea that recombination is the key event in generation of novel mobile genetic elements. Teratorn is a large mobile genetic element originally identified in the small teleost fish medaka. Here, the authors show that Teratorn is derived from the fusion of a piggyBac superfamily DNA transposon and an alloherpesvirus and that it is widely found across teleost fish.
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39
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Frank JA, Feschotte C. Co-option of endogenous viral sequences for host cell function. Curr Opin Virol 2017; 25:81-89. [PMID: 28818736 DOI: 10.1016/j.coviro.2017.07.021] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/13/2017] [Accepted: 07/23/2017] [Indexed: 01/26/2023]
Abstract
Eukaryotic genomes are littered with sequences of diverse viral origins, termed endogenous viral elements (EVEs). Here we used examples primarily drawn from mammalian endogenous retroviruses to document how the influx of EVEs has provided a source of prefabricated coding and regulatory sequences that were formerly utilized for viral infection and replication, but have been occasionally repurposed for cellular function. While EVE co-option has benefited a variety of host biological functions, there appears to be a disproportionate contribution to immunity and antiviral defense. The mammalian embryo and placenta offer opportunistic routes of viral transmission to the next host generation and as such they represent hotbeds for EVE cooption. Based on these observations, we propose that EVE cooption is initially driven as a mean to mitigate conflicts between host and viruses, which in turn acts as a stepping-stone toward the evolution of cellular innovations serving host physiology and development.
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Affiliation(s)
- John A Frank
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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40
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Disentangling the origins of virophages and polintons. Curr Opin Virol 2017; 25:59-65. [PMID: 28802203 DOI: 10.1016/j.coviro.2017.07.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/10/2017] [Accepted: 07/14/2017] [Indexed: 01/04/2023]
Abstract
Virophages and polintons are part of a complex system that also involves eukaryotes, giant viruses, as well as other viruses and transposable elements. Virophages are cosmopolitan, being found in environments ranging from the Amazon River to Antarctic hypersaline lakes, while polintons are found in many single celled and multicellular eukaryotes. Virophages and polintons have a shared ancestry, but their exact origins are unknown and obscured by antiquity and extensive horizontal gene transfer (HGT). Paleovirology can help disentangle the complicated gene flow between these two, as well as their giant viral and eukaryotic hosts. We outline the evidence and theoretical support for polintons being descended from viruses and not vice versa. In order to disentangle the natural history of polintons and virophages, we suggest that there is much to be gained by embracing rigorous metagenomics and evolutionary analyses. Methods from paleovirology will play a pivotal role in unravelling ancient relationships, HGT and patterns of cross-species transmission.
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41
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Viruses as vectors of horizontal transfer of genetic material in eukaryotes. Curr Opin Virol 2017; 25:16-22. [DOI: 10.1016/j.coviro.2017.06.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/18/2017] [Accepted: 06/13/2017] [Indexed: 01/04/2023]
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42
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Koonin EV, Krupovic M. Polintons, virophages and transpovirons: a tangled web linking viruses, transposons and immunity. Curr Opin Virol 2017; 25:7-15. [PMID: 28672161 DOI: 10.1016/j.coviro.2017.06.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/30/2017] [Accepted: 06/19/2017] [Indexed: 11/15/2022]
Abstract
Virophages are satellite DNA viruses that depend for their replication on giant viruses of the family Mimiviridae. An evolutionary relationship exists between the virophages and Polintons, large self-synthesizing transposons that are wide spread in the genomes of diverse eukaryotes. Most of the Polintons encode homologs of major and minor icosahedral virus capsid proteins and accordingly are predicted to form virions. Additionally, metagenome analysis has led to the discovery of an expansive family of Polinton-like viruses (PLV) that are more distantly related to bona fide Polintons and virophages. Another group of giant virus parasites includes small, linear, double-stranded DNA elements called transpovirons. Recent in-depth comparative genomic analysis has yielded evidence of the origin of the PLV and the transpovirons from Polintons. Integration of virophage genomes into genomes of both giant viruses and protists has been demonstrated. Furthermore, in an experimental coinfection system that consisted of a protist host, a giant virus and an associated virophage, the virophage integrated into the host genome and, after activation of its expression by a superinfecting giant virus, served as an agent of adaptive immunity. There is a striking analogy between this mechanism and the CRISPR-Cas system of prokaryotic adaptive immunity. Taken together, these findings show that Polintons, PLV, virophages and transpovirons form a dynamic network of integrating mobile genetic elements that contribute to the cellular antivirus defense and host-virus coevolution.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| | - Mart Krupovic
- Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Institut Pasteur, Paris, France.
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43
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Moniruzzaman M, Wurch LL, Alexander H, Dyhrman ST, Gobler CJ, Wilhelm SW. Virus-host relationships of marine single-celled eukaryotes resolved from metatranscriptomics. Nat Commun 2017; 8:16054. [PMID: 28656958 PMCID: PMC5493757 DOI: 10.1038/ncomms16054] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 05/16/2017] [Indexed: 01/12/2023] Open
Abstract
Establishing virus–host relationships has historically relied on culture-dependent approaches. Here we report on the use of marine metatranscriptomics to probe virus–host relationships. Statistical co-occurrence analyses of dsDNA, ssRNA and dsRNA viral markers of polyadenylation-selected RNA sequences from microbial communities dominated by Aureococcus anophagefferens (Quantuck Bay, NY), and diatoms (Narragansett Bay, RI) show active infections by diverse giant viruses (NCLDVs) associated with algal and nonalgal hosts. Ongoing infections of A. anophagefferens by a known Mimiviridae (AaV) occur during bloom peak and decline. Bloom decline is also accompanied by increased activity of viruses other than AaV, including (+) ssRNA viruses. In Narragansett Bay, increased temporal resolution reveals active NCLDVs with both ‘boom-and-bust’ and ‘steady-state infection’-like ecologies that include known as well as novel virus–host interactions. Our approach offers a method for screening active viral infections and develops links between viruses and their potential hosts in situ. Our observations further demonstrate that previously unknown virus–host relationships in marine systems are abundant. Viruses are partners in ecosystem ecology, yet their study has been primarily limited to laboratory models virus-host or derived from metagenomics. Here, Moniruzzaman et al. use metatranscriptomics to resolve interactions between giant viruses and single-celled eukaryotic hosts.
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Affiliation(s)
- Mohammad Moniruzzaman
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Louie L Wurch
- Department of Biology, James Madison University, Harrisonburg, Virginia 22807, USA
| | - Harriet Alexander
- Department of Earth and Environmental Science and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
| | - Sonya T Dyhrman
- Department of Earth and Environmental Science and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA
| | - Christopher J Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794, USA
| | - Steven W Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee 37996, USA
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44
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Host genome integration and giant virus-induced reactivation of the virophage mavirus. Nature 2017; 540:288-291. [PMID: 27929021 DOI: 10.1038/nature20593] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 11/02/2016] [Indexed: 11/08/2022]
Abstract
Endogenous viral elements are increasingly found in eukaryotic genomes, yet little is known about their origins, dynamics, or function. Here we provide a compelling example of a DNA virus that readily integrates into a eukaryotic genome where it acts as an inducible antiviral defence system. We found that the virophage mavirus, a parasite of the giant Cafeteria roenbergensis virus (CroV), integrates at multiple sites within the nuclear genome of the marine protozoan Cafeteria roenbergensis. The endogenous mavirus is structurally and genetically similar to eukaryotic DNA transposons and endogenous viruses of the Maverick/Polinton family. Provirophage genes are not constitutively expressed, but are specifically activated by superinfection with CroV, which induces the production of infectious mavirus particles. Virophages can inhibit the replication of mimivirus-like giant viruses and an anti-viral protective effect of provirophages on their hosts has been hypothesized. We find that provirophage-carrying cells are not directly protected from CroV; however, lysis of these cells releases infectious mavirus particles that are then able to suppress CroV replication and enhance host survival during subsequent rounds of infection. The microbial host-parasite interaction described here involves an altruistic aspect and suggests that giant-virus-induced activation of provirophages might be ecologically relevant in natural protist populations.
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45
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Wilhelm SW, Bird JT, Bonifer KS, Calfee BC, Chen T, Coy SR, Gainer PJ, Gann ER, Heatherly HT, Lee J, Liang X, Liu J, Armes AC, Moniruzzaman M, Rice JH, Stough JMA, Tams RN, Williams EP, LeCleir GR. A Student's Guide to Giant Viruses Infecting Small Eukaryotes: From Acanthamoeba to Zooxanthellae. Viruses 2017; 9:E46. [PMID: 28304329 PMCID: PMC5371801 DOI: 10.3390/v9030046] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
The discovery of infectious particles that challenge conventional thoughts concerning "what is a virus" has led to the evolution a new field of study in the past decade. Here, we review knowledge and information concerning "giant viruses", with a focus not only on some of the best studied systems, but also provide an effort to illuminate systems yet to be better resolved. We conclude by demonstrating that there is an abundance of new host-virus systems that fall into this "giant" category, demonstrating that this field of inquiry presents great opportunities for future research.
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Affiliation(s)
- Steven W Wilhelm
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Jordan T Bird
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Kyle S Bonifer
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Benjamin C Calfee
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Tian Chen
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Samantha R Coy
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - P Jackson Gainer
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Eric R Gann
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Huston T Heatherly
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Jasper Lee
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Xiaolong Liang
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Jiang Liu
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - April C Armes
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Mohammad Moniruzzaman
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - J Hunter Rice
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Joshua M A Stough
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Robert N Tams
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Evan P Williams
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
| | - Gary R LeCleir
- The Department of Microbiology, The University of Tennessee, Knoxville, TN 37996, USA.
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46
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Koonin EV, Krupovic M. Virology: A parasite's parasite saves host's neighbours. Nature 2017; 540:204-205. [PMID: 27929010 DOI: 10.1038/540204a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20894, USA
| | - Mart Krupovic
- Department of Microbiology, Institut Pasteur, Paris 75015, France
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47
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Colson P, La Scola B, Levasseur A, Caetano-Anollés G, Raoult D. Mimivirus: leading the way in the discovery of giant viruses of amoebae. Nat Rev Microbiol 2017; 15:243-254. [PMID: 28239153 PMCID: PMC7096837 DOI: 10.1038/nrmicro.2016.197] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acanthamoeba polyphaga mimivirus (APMV) and subsequently discovered giant viruses of amoebae challenge the previous definition of viruses and their classification. The replication cycle, structure, genomic make-up and plasticity of giant viruses differ from those of traditional viruses. They extend the definition of viruses into a broader range of biological entities, some of which are very simple and others of which have a complexity that is comparable to that of other microorganisms. Giant viruses of amoebae have virus particles as large as some microorganisms that are visible by light microscopy and that have a stunning level of complexity. Their genomes are mosaics and contain large repertoires of genes, some of which are hallmarks of cellular organisms, although the majority of which have unknown functions. Mimiviruses are associated with a specific mobilome and are parasitized by viruses that they can defend against. Several hypotheses on the ancient origin and evolutionary relationship between cellular organisms and giant viruses of amoebae have been proposed, and these topics continue to be debated. The detection of giant viruses of amoebae in humans and the study of their potential pathogenicity are emerging fields.
The discovery of the giant amoebal virus mimivirus, in 2003, opened up a new area of virology. Extended studies, including those of mimiviruses, have since revealed that these viruses have genetic, proteomic and structural features that are more complex than those of conventional viruses. The accidental discovery of the giant virus of amoeba — Acanthamoeba polyphaga mimivirus (APMV; more commonly known as mimivirus) — in 2003 changed the field of virology. Viruses were previously defined by their submicroscopic size, which probably prevented the search for giant viruses, which are visible by light microscopy. Extended studies of giant viruses of amoebae revealed that they have genetic, proteomic and structural complexities that were not thought to exist among viruses and that are comparable to those of bacteria, archaea and small eukaryotes. The giant virus particles contain mRNA and more than 100 proteins, they have gene repertoires that are broader than those of other viruses and, notably, some encode translation components. The infection cycles of giant viruses of amoebae involve virus entry by amoebal phagocytosis and replication in viral factories. In addition, mimiviruses are infected by virophages, defend against them through the mimivirus virophage resistance element (MIMIVIRE) system and have a unique mobilome. Overall, giant viruses of amoebae, including mimiviruses, marseilleviruses, pandoraviruses, pithoviruses, faustoviruses and molliviruses, challenge the definition and classification of viruses, and have increasingly been detected in humans.
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Affiliation(s)
- Philippe Colson
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Bernard La Scola
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Anthony Levasseur
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
| | - Gustavo Caetano-Anollés
- Evolutionary Bioinformatics Laboratory, Department of Crop Sciences, University of Illinois, 332 National Soybean Research Center, 1101 West Peabody Drive, Urbana, Illinois 61801, USA
| | - Didier Raoult
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Aix-Marseille University, UM63, CNRS 7278, IRD 198, INSERM 1095, Institut Hospitalo-Universitaire (IHU) - Méditerranée Infection, AP-HM, 19-21 Boulevard Jean Moulin, 13385 Marseille, France
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48
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A Glimpse of Nucleo-Cytoplasmic Large DNA Virus Biodiversity through the Eukaryotic Genomics Window. Viruses 2017; 9:v9010017. [PMID: 28117696 PMCID: PMC5294986 DOI: 10.3390/v9010017] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 12/16/2022] Open
Abstract
The nucleocytoplasmic large DNA viruses (NCLDV) are a group of extremely complex double-stranded DNA viruses, which are major parasites of a variety of eukaryotes. Recent studies showed that certain eukaryotes contain fragments of NCLDV DNA integrated in their genome, when surprisingly many of these organisms were not previously shown to be infected by NCLDVs. We performed an update survey of NCLDV genes hidden in eukaryotic sequences to measure the incidence of this phenomenon in common public sequence databases. A total of 66 eukaryotic genomic or transcriptomic datasets-many of which are from algae and aquatic protists-contained at least one of the five most consistently conserved NCLDV core genes. Phylogenetic study of the eukaryotic NCLDV-like sequences identified putative new members of already recognized viral families, as well as members of as yet unknown viral clades. Genomic evidence suggested that most of these sequences resulted from viral DNA integrations rather than contaminating viruses. Furthermore, the nature of the inserted viral genes helped predicting original functional capacities of the donor viruses. These insights confirm that genomic insertions of NCLDV DNA are common in eukaryotes and can be exploited to delineate the contours of NCLDV biodiversity.
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49
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Maumus F, Blanc G. Study of Gene Trafficking between Acanthamoeba and Giant Viruses Suggests an Undiscovered Family of Amoeba-Infecting Viruses. Genome Biol Evol 2016; 8:3351-3363. [PMID: 27811174 PMCID: PMC5203793 DOI: 10.1093/gbe/evw260] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2016] [Indexed: 01/10/2023] Open
Abstract
The nucleocytoplasmic large DNA viruses (NCLDV) are a group of extremely complex double-stranded DNA viruses, which are major parasites of a variety of eukaryotes. Recent studies showed that certain unicellular eukaryotes contain fragments of NCLDV DNA integrated in their genome, when surprisingly many of these organisms were not previously shown to be infected by NCLDVs. These findings prompted us to search the genome of Acanthamoeba castellanii strain Neff (Neff), one of the most prolific hosts in the discovery of giant NCLDVs, for possible DNA inserts of viral origin. We report the identification of 267 markers of lateral gene transfer with viruses, approximately half of which are clustered in Neff genome regions of viral origins, transcriptionally inactive or exhibit nucleotide-composition signatures suggestive of a foreign origin. The integrated viral genes had diverse origin among relatives of viruses that infect Neff, including Mollivirus, Pandoravirus, Marseillevirus, Pithovirus, and Mimivirus However, phylogenetic analysis suggests the existence of a yet-undiscovered family of amoeba-infecting NCLDV in addition to the five already characterized. The active transcription of some apparently anciently integrated virus-like genes suggests that some viral genes might have been domesticated during the amoeba evolution. These insights confirm that genomic insertion of NCLDV DNA is a common theme in eukaryotes. This gene flow contributed fertilizing the eukaryotic gene repertoire and participated in the occurrence of orphan genes, a long standing issue in genomics. Search for viral inserts in eukaryotic genomes followed by environmental screening of the original viruses should be used to isolate radically new NCLDVs.
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Affiliation(s)
| | - Guillaume Blanc
- Structural and Genomic Information Laboratory (IGS), Aix-Marseille Université, CNRS UMR (IMM FR 3479), Marseille, France
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50
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Fu W, Chaiboonchoe A, Khraiwesh B, Nelson DR, Al-Khairy D, Mystikou A, Alzahmi A, Salehi-Ashtiani K. Algal Cell Factories: Approaches, Applications, and Potentials. Mar Drugs 2016; 14:md14120225. [PMID: 27983586 PMCID: PMC5192462 DOI: 10.3390/md14120225] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 12/26/2022] Open
Abstract
With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive “cell factories”: the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO2, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineering methods that we may see the full biotechnological potential of microalgae come to fruition. Thus, in this review, we address past and present endeavors towards the aim of creating productive algal cell factories and describe possible advantageous future directions for the field.
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Affiliation(s)
- Weiqi Fu
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amphun Chaiboonchoe
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Basel Khraiwesh
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - David R Nelson
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Dina Al-Khairy
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Alexandra Mystikou
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amnah Alzahmi
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Kourosh Salehi-Ashtiani
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
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