1
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Höfler T, Nascimento MM, Zeitlow M, Kim JY, Trimpert J. Evolutionary Dynamics of Accelerated Antiviral Resistance Development in Hypermutator Herpesvirus. Mol Biol Evol 2024; 41:msae119. [PMID: 38879872 PMCID: PMC11226790 DOI: 10.1093/molbev/msae119] [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: 02/04/2024] [Revised: 05/09/2024] [Accepted: 06/12/2024] [Indexed: 07/07/2024] Open
Abstract
Antiviral therapy is constantly challenged by the emergence of resistant pathogens. At the same time, experimental approaches to understand and predict resistance are limited by long periods required for evolutionary processes. Here, we present a herpes simplex virus 1 mutant with impaired proofreading capacity and consequently elevated mutation rates. Comparing this hypermutator to parental wild type virus, we study the evolution of antiviral drug resistance in vitro. We model resistance development and elucidate underlying genetic changes against three antiviral substances. Our analyzes reveal no principle difference in the evolutionary behavior of both viruses, adaptive processes are overall similar, however significantly accelerated for the hypermutator. We conclude that hypermutator viruses are useful for modeling adaptation to antiviral therapy. They offer the benefit of expedited adaptation without introducing apparent bias and can therefore serve as an accelerator to predict natural evolution.
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Affiliation(s)
- Thomas Höfler
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Berlin, Germany
| | - Mariana Mara Nascimento
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Berlin, Germany
| | - Michaela Zeitlow
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Berlin, Germany
| | - Ji Yoon Kim
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Berlin, Germany
| | - Jakob Trimpert
- Institut für Virologie, Fachbereich Veterinärmedizin, Freie Universität Berlin, Berlin, Germany
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
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2
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Moniruzzaman M, Erazo Garcia MP, Farzad R, Ha AD, Jivaji A, Karki S, Sheyn U, Stanton J, Minch B, Stephens D, Hancks DC, Rodrigues RAL, Abrahao JS, Vardi A, Aylward FO. Virologs, viral mimicry, and virocell metabolism: the expanding scale of cellular functions encoded in the complex genomes of giant viruses. FEMS Microbiol Rev 2023; 47:fuad053. [PMID: 37740576 PMCID: PMC10583209 DOI: 10.1093/femsre/fuad053] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 08/29/2023] [Accepted: 09/21/2023] [Indexed: 09/24/2023] Open
Abstract
The phylum Nucleocytoviricota includes the largest and most complex viruses known. These "giant viruses" have a long evolutionary history that dates back to the early diversification of eukaryotes, and over time they have evolved elaborate strategies for manipulating the physiology of their hosts during infection. One of the most captivating of these mechanisms involves the use of genes acquired from the host-referred to here as viral homologs or "virologs"-as a means of promoting viral propagation. The best-known examples of these are involved in mimicry, in which viral machinery "imitates" immunomodulatory elements in the vertebrate defense system. But recent findings have highlighted a vast and rapidly expanding array of other virologs that include many genes not typically found in viruses, such as those involved in translation, central carbon metabolism, cytoskeletal structure, nutrient transport, vesicular trafficking, and light harvesting. Unraveling the roles of virologs during infection as well as the evolutionary pathways through which complex functional repertoires are acquired by viruses are important frontiers at the forefront of giant virus research.
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Affiliation(s)
- Mohammad Moniruzzaman
- Rosenstiel School of Marine Atmospheric, and Earth Science, University of Miami, Coral Gables, FL 33149, United States
| | - Maria Paula Erazo Garcia
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Roxanna Farzad
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Anh D Ha
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Abdeali Jivaji
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Sangita Karki
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Uri Sheyn
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Joshua Stanton
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
| | - Benjamin Minch
- Rosenstiel School of Marine Atmospheric, and Earth Science, University of Miami, Coral Gables, FL 33149, United States
| | - Danae Stephens
- Rosenstiel School of Marine Atmospheric, and Earth Science, University of Miami, Coral Gables, FL 33149, United States
| | - Dustin C Hancks
- Department of Immunology, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX, United States
| | - Rodrigo A L Rodrigues
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Jonatas S Abrahao
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, MG, Brazil
| | - Assaf Vardi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Frank O Aylward
- Department of Biological Sciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA 24061, United States
- Center for Emerging, Zoonotic, and Arthropod-Borne Infectious Disease, Virginia Tech, Blacksburg, VA 24061, United States
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3
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Forterre P, Gaïa M. [Viruses and the evolution of modern eukaryotic cells]. Med Sci (Paris) 2022; 38:990-998. [PMID: 36692278 DOI: 10.1051/medsci/2022164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
It is now well accepted that viruses have played an important role in the evolution of modern eukaryotes. In this review, we suggest that interactions between ancient eukaryoviruses and proto-eukaryotes also played a major role in eukaryogenesis. We discuss phylogenetic analyses that highlight the viral origin of several key proteins in the molecular biology of eukaryotes. We also discuss recent observations that, by analogy, could suggest a viral origin of the cellular nucleus. Finally, we hypothesize that mechanisms of cell differentiation in multicellular organisms might have originated from mechanisms implemented by viruses to transform infected cells into virocells.
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Affiliation(s)
- Patrick Forterre
- Département de microbiologie, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France - Institut de biologie intégrative de la cellule (I2BC), Département de microbiologie, CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Morgan Gaïa
- Génomique métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057 Évry, France
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4
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Talbert PB, Armache KJ, Henikoff S. Viral histones: pickpocket's prize or primordial progenitor? Epigenetics Chromatin 2022; 15:21. [PMID: 35624484 PMCID: PMC9145170 DOI: 10.1186/s13072-022-00454-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/19/2022] [Indexed: 12/12/2022] Open
Abstract
The common histones H2A, H2B, H3, and H4 are the characteristic components of eukaryotic nucleosomes, which function to wrap DNA and compact the genome as well as to regulate access to DNA for transcription and replication in all eukaryotes. In the past two decades, histones have also been found to be encoded in some DNA viruses, where their functions and properties are largely unknown, though recently histones from two related viruses have been shown to form nucleosome-like structures in vitro. Viral histones can be highly similar to eukaryotic histones in primary sequence, suggesting they have been recently picked up from eukaryotic hosts, or they can be radically divergent in primary sequence and may occur as conjoined histone doublets, triplets, or quadruplets, suggesting ancient origins prior to the divergence of modern eukaryotes. Here, we review what is known of viral histones and discuss their possible origins and functions. We consider how the viral life cycle may affect their properties and histories, and reflect on the possible roles of viruses in the origin of the nucleus of modern eukaryotic cells.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute and Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA
| | - Karim-Jean Armache
- Skirball Institute of Biomolecular Medicine, Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, 550 First Ave, New York, NY, 10016, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute and Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA.
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5
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Da Cunha V, Gaia M, Ogata H, Jaillon O, Delmont TO, Forterre P. Giant viruses encode actin-related proteins. Mol Biol Evol 2022; 39:6527639. [PMID: 35150280 PMCID: PMC8850707 DOI: 10.1093/molbev/msac022] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The emergence of the eukaryotic cytoskeleton is a critical yet puzzling step of eukaryogenesis. Actin and actin-related proteins (ARPs) are ubiquitous components of this cytoskeleton. The gene repertoire of the Last Eukaryotic Common Ancestor (LECA) would have therefore harbored both actin and various ARPs. Here, we report the presence and expression of actin-related genes in viral genomes (viractins) of some Imitervirales, a viral order encompassing the giant Mimiviridae. Phylogenetic analyses suggest an early recruitment of an actin-related gene by viruses from ancient proto-eukaryotic hosts before the emergence of modern eukaryotes, possibly followed by a back transfer that gave rise to eukaryotic actins. This supports a co-evolutionary scenario between pre-LECA lineages and their viruses, which could have contributed to the emergence of the modern eukaryotic cytoskeleton.
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Affiliation(s)
- Violette Da Cunha
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, 91198, France
| | - Morgan Gaia
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, Evry, 91057, France
| | - Hiroyuki Ogata
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, 611-0011, Japan
| | - Olivier Jaillon
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, Evry, 91057, France.,Research Federation for the Study of Global Ocean Systems Ecology and Evolution, Tara Oceans, FR2022, France /
| | - Tom O Delmont
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, Evry, 91057, France
| | - Patrick Forterre
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, 91198, France.,Département de Microbiologie, Institut Pasteur, 25 rue du Docteur Roux, Paris, 75017, France
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6
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Patil S, Kondabagil K. Coevolutionary and Phylogenetic Analysis of Mimiviral Replication Machinery Suggest the Cellular Origin of Mimiviruses. Mol Biol Evol 2021; 38:2014-2029. [PMID: 33570580 PMCID: PMC8097291 DOI: 10.1093/molbev/msab003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mimivirus is one of the most complex and largest viruses known. The origin and evolution of Mimivirus and other giant viruses have been a subject of intense study in the last two decades. The two prevailing hypotheses on the origin of Mimivirus and other viruses are the reduction hypothesis, which posits that viruses emerged from modern unicellular organisms; whereas the virus-first hypothesis proposes viruses as relics of precellular forms of life. In this study, to gain insights into the origin of Mimivirus, we have carried out extensive phylogenetic, correlation, and multidimensional scaling analyses of the putative proteins involved in the replication of its 1.2-Mb large genome. Correlation analysis and multidimensional scaling methods were validated using bacteriophage, bacteria, archaea, and eukaryotic replication proteins before applying to Mimivirus. We show that a large fraction of mimiviral replication proteins, including polymerase B, clamp, and clamp loaders are of eukaryotic origin and are coevolving. Although phylogenetic analysis places some components along the lineages of phage and bacteria, we show that all the replication-related genes have been homogenized and are under purifying selection. Collectively our analysis supports the idea that Mimivirus originated from a complex cellular ancestor. We hypothesize that Mimivirus has largely retained complex replication machinery reminiscent of its progenitor while losing most of the other genes related to processes such as metabolism and translation.
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Affiliation(s)
- Supriya Patil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, India
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7
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Xian Y, Avila R, Pant A, Yang Z, Xiao C. The Role of Tape Measure Protein in Nucleocytoplasmic Large DNA Virus Capsid Assembly. Viral Immunol 2020; 34:41-48. [PMID: 33074779 DOI: 10.1089/vim.2020.0038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nucleocytoplasmic large DNA viruses (NCLDVs) are a group of large viruses that infect a wide range of hosts, from animals to protists. These viruses are grouped together in NCLDV based on genomic sequence analyses. They share a set of essential genes for virion morphogenesis and replication. Most NCLDVs generally have large physical sizes while their morphologies vary in different families, such as icosahedral, brick, or oval shape, raising the question of the possible regulatory factor on their morphogenesis. The capsids of icosahedral NCLDVs are assembled from small building blocks, named capsomers, which are the trimeric form of the major capsid proteins. Note that the capsids of immature poxvirus are spherical even though they are assembled from capsomers that share high structural conservation with those icosahedral NCLDVs. The recently published high resolution structure of NCLDVs, Paramecium bursaria Chlorella virus 1 and African swine fever virus, described the intensive network of minor capsid proteins that are located underneath the capsomers. Among these minor proteins is the elongated tape measure protein (TmP) that spans from one icosahedral fivefold vertex to another. In this study, we focused on the critical roles that TmP plays in the assembly of icosahedral NCLDV capsids, answering a question raised in a previously proposed spiral mechanism. Interestingly, basic local alignment search on the TmPs showed no significant hits in poxviruses, which might be the factor that differentiates poxviruses and icosahedral NCLDVs in their morphogenesis.
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Affiliation(s)
- Yuejiao Xian
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas, USA
| | - Ricardo Avila
- Bioinformatics Program, University of Texas at El Paso, El Paso, Texas, USA
| | - Anil Pant
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Zhilong Yang
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso, Texas, USA
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8
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Takemura M. Medusavirus Ancestor in a Proto-Eukaryotic Cell: Updating the Hypothesis for the Viral Origin of the Nucleus. Front Microbiol 2020; 11:571831. [PMID: 33013805 PMCID: PMC7494782 DOI: 10.3389/fmicb.2020.571831] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/17/2020] [Indexed: 12/24/2022] Open
Abstract
The mechanistic evolutionary origin of the eukaryotic cell nucleus remains unknown. Among several plausible hypotheses, the most controversial is that large DNA viruses, such as poxviruses, led to the emergence of the eukaryotic cell nucleus. Several recent findings, including the discovery of a nucleus-like structure in prokaryotic viruses and prokaryotes possessing nucleus-like inner membranes, suggest genomic DNA compartmentalization not only in eukaryotes but also in prokaryotes. The sophisticated viral machinery of mimiviruses is thought to resemble the eukaryotic nucleus: DNA replicates both inside the viral factory and nucleus, which is at least partially surrounded by membranes and is devoid of ribosomes. Furthermore, several features of the recently identified Acanthamoeba castellanii medusavirus suggest that the evolutionary relationship between ancestral viral factory and eukaryotic nucleus. Notably, Ran, DNA polymerase, and histones show molecular fossils of lateral transfer of nuclear genes between the virus and host. These results suggest viral innovation in the emergence of the eukaryotic nucleus. According to these results, a new scenario explaining the origin of the eukaryotic nucleus from the perspective of viral participation is proposed. This new scenario could substantially impact the study of eukaryogenesis and stimulate further discussion about viral contributions to the evolution of the eukaryotic nucleus.
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Affiliation(s)
- Masaharu Takemura
- Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science, Tokyo, Japan
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9
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Diversification of giant and large eukaryotic dsDNA viruses predated the origin of modern eukaryotes. Proc Natl Acad Sci U S A 2019; 116:19585-19592. [PMID: 31506349 DOI: 10.1073/pnas.1912006116] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Giant and large eukaryotic double-stranded DNA viruses from the Nucleo-Cytoplasmic Large DNA Virus (NCLDV) assemblage represent a remarkably diverse and potentially ancient component of the eukaryotic virome. However, their origin(s), evolution, and potential roles in the emergence of modern eukaryotes remain subjects of intense debate. Here we present robust phylogenetic trees of NCLDVs, based on the 8 most conserved proteins responsible for virion morphogenesis and informational processes. Our results uncover the evolutionary relationships between different NCLDV families and support the existence of 2 superclades of NCLDVs, each encompassing several families. We present evidence strongly suggesting that the NCLDV core genes, which are involved in both informational processes and virion formation, were acquired vertically from a common ancestor. Among them, the largest subunits of the DNA-dependent RNA polymerase were transferred between 2 clades of NCLDVs and proto-eukaryotes, giving rise to 2 of the 3 eukaryotic DNA-dependent RNA polymerases. Our results strongly suggest that these transfers and the diversification of NCLDVs predated the emergence of modern eukaryotes, emphasizing the major role of viruses in the evolution of cellular domains.
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10
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Aoki K, Hagiwara R, Akashi M, Sasaki K, Murata K, Ogata H, Takemura M. Fifteen Marseilleviruses Newly Isolated From Three Water Samples in Japan Reveal Local Diversity of Marseilleviridae. Front Microbiol 2019; 10:1152. [PMID: 31178850 PMCID: PMC6543897 DOI: 10.3389/fmicb.2019.01152] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/06/2019] [Indexed: 11/13/2022] Open
Abstract
The family Marseilleviridae, defined as a group of icosahedral double-stranded DNA viruses with particle size of approximately 250 nm and genome size of 350-380 kbp, belongs to the nucleo-cytoplasmic family of large DNA viruses. The family Marseilleviridae is currently classified into lineages A-E. In this study, we isolated 12 or 15 new members of the family Marseilleviridae from three sampling locations in Japan. Molecular phylogenetic analysis of the MCP genes showed that the new viruses could be further classified into three groups, hokutoviruses, kashiwazakiviruses, and kyotoviruses. Hokutoviruses were closely related to lineage B, kyotoviruses were related to lineage A, and kashiwazakiviruses were also classified into lineage B but a new putative subgroup of lineage B, revealing the diversity of this lineage. Interestingly, more than two viruses with slightly different MCP genes were isolated from a single water sample from a single location, i.e., two hokutoviruses and one kashiwazakivirus were isolated from a small reservoir, five kashiwazakiviruses from the mouth of a river, and five kyotoviruses from fresh water of a river, suggesting that several milliliters of water samples contain several types of giant viruses. Amoeba cells infected with hokutoviruses or kashiwazakiviruses exhibited a "bunch" formation consisting of normal and infected cells similarly to a tupanvirus, whereas cells infected with kyotoviruses or tokyovirus did not. These results suggest the previously unrecognized local diversity of the family Marseilleviridae in aquatic environments.
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Affiliation(s)
- Keita Aoki
- Laboratory of Biology, Graduate School of Mathematics and Science Education, Tokyo University of Science, Tokyo, Japan
| | - Reika Hagiwara
- Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science, Tokyo, Japan
| | - Motohiro Akashi
- Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science, Tokyo, Japan
| | - Kenta Sasaki
- Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science, Tokyo, Japan
| | | | - Hiroyuki Ogata
- Institute for Chemical Research, Kyoto University, Gokasho, Japan
| | - Masaharu Takemura
- Laboratory of Biology, Graduate School of Mathematics and Science Education, Tokyo University of Science, Tokyo, Japan.,Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science, Tokyo, Japan
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11
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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: 85] [Impact Index Per Article: 17.0] [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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12
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Claverie JM, Abergel C, Legendre M. [Giant viruses that create their own genes]. Med Sci (Paris) 2019; 34:1087-1091. [PMID: 30623766 DOI: 10.1051/medsci/2018300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Since 2003 and the discovery of Mimivirus, the saga of giant viruses continues with the isolation of new amoeba viruses, which are now divided into seven distinct families, the origin (s) of which are still mysterious and controversial. Thanks to the isolation of 3 new members of the Pandoraviridae family, whose micrometric particles and genomes of more than 2 megabases encroach on the cellular world, we carried out a stringent re-analysis of their gene contents, using a combination of transcriptomic, proteomic and bioinformatic approaches. We concluded that the only scenario capable of accounting for the distribution and the huge proportion of orphan genes ("ORFans") that characterize Pandoraviruses is that they were created de novo within the intergenic regions. This process, perhaps shared among other large DNA viruses, challenges the central paradigm of molecular evolution according to which all genes / proteins have an ancestry history.
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Affiliation(s)
- Jean-Michel Claverie
- Aix-Marseille université et CNRS, Information génomique et structurale (IGS), UMR7256, Institut de microbiologie de la Méditerranée-IMM-FR 3479, parc scientifique de Luminy, 163, avenue de Luminy, case 934, 13288 Marseille Cedex 09, France
| | - Chantal Abergel
- Aix-Marseille université et CNRS, Information génomique et structurale (IGS), UMR7256, Institut de microbiologie de la Méditerranée-IMM-FR 3479, parc scientifique de Luminy, 163, avenue de Luminy, case 934, 13288 Marseille Cedex 09, France
| | - Matthieu Legendre
- Aix-Marseille université et CNRS, Information génomique et structurale (IGS), UMR7256, Institut de microbiologie de la Méditerranée-IMM-FR 3479, parc scientifique de Luminy, 163, avenue de Luminy, case 934, 13288 Marseille Cedex 09, France
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13
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Archaeal DNA polymerases: new frontiers in DNA replication and repair. Emerg Top Life Sci 2018; 2:503-516. [PMID: 33525823 DOI: 10.1042/etls20180015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 09/27/2018] [Accepted: 10/08/2018] [Indexed: 11/17/2022]
Abstract
Archaeal DNA polymerases have long been studied due to their superior properties for DNA amplification in the polymerase chain reaction and DNA sequencing technologies. However, a full comprehension of their functions, recruitment and regulation as part of the replisome during genome replication and DNA repair lags behind well-established bacterial and eukaryotic model systems. The archaea are evolutionarily very broad, but many studies in the major model systems of both Crenarchaeota and Euryarchaeota are starting to yield significant increases in understanding of the functions of DNA polymerases in the respective phyla. Recent advances in biochemical approaches and in archaeal genetic models allowing knockout and epitope tagging have led to significant increases in our understanding, including DNA polymerase roles in Okazaki fragment maturation on the lagging strand, towards reconstitution of the replisome itself. Furthermore, poorly characterised DNA polymerase paralogues are finding roles in DNA repair and CRISPR immunity. This review attempts to provide a current update on the roles of archaeal DNA polymerases in both DNA replication and repair, addressing significant questions that remain for this field.
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Mihara T, Koyano H, Hingamp P, Grimsley N, Goto S, Ogata H. Taxon Richness of "Megaviridae" Exceeds those of Bacteria and Archaea in the Ocean. Microbes Environ 2018; 33:162-171. [PMID: 29806626 PMCID: PMC6031395 DOI: 10.1264/jsme2.me17203] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Since the discovery of the giant mimivirus, evolutionarily related viruses have been isolated or identified from various environments. Phylogenetic analyses of this group of viruses, tentatively referred to as the family “Megaviridae”, suggest that it has an ancient origin that may predate the emergence of major eukaryotic lineages. Environmental genomics has since revealed that Megaviridae represents one of the most abundant and diverse groups of viruses in the ocean. In the present study, we compared the taxon richness and phylogenetic diversity of Megaviridae, Bacteria, and Archaea using DNA-dependent RNA polymerase as a common marker gene. By leveraging existing microbial metagenomic data, we found higher richness and phylogenetic diversity in this single viral family than in the two prokaryotic domains. We also obtained results showing that the evolutionary rate alone cannot account for the observed high diversity of Megaviridae lineages. These results suggest that the Megaviridae family has a deep co-evolutionary history with diverse marine protists since the early “Big-Bang” radiation of the eukaryotic tree of life.
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Affiliation(s)
- Tomoko Mihara
- Bioinformatics Center, Institute for Chemical Research, Kyoto University
| | - Hitoshi Koyano
- School of Life Science and Technology, Laboratory of Genome Informatics, Tokyo Institute of Technology
| | | | - Nigel Grimsley
- Integrative Marine Biology Laboratory (BIOM), CNRS UMR7232, Sorbonne Universities
| | - Susumu Goto
- Database Center for Life Science, Joint-Support Center for Data Science Research, Research Organization of Information and Systems
| | - Hiroyuki Ogata
- Bioinformatics Center, Institute for Chemical Research, Kyoto University
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15
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Philosof A, Yutin N, Flores-Uribe J, Sharon I, Koonin EV, Béjà O. Novel Abundant Oceanic Viruses of Uncultured Marine Group II Euryarchaeota. Curr Biol 2017; 27:1362-1368. [PMID: 28457865 PMCID: PMC5434244 DOI: 10.1016/j.cub.2017.03.052] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 03/09/2017] [Accepted: 03/21/2017] [Indexed: 12/16/2022]
Abstract
Marine group II Euryarchaeota (MG-II) are among the most abundant microbes in oceanic surface waters [1, 2, 3, 4]. So far, however, representatives of MG-II have not been cultivated, and no viruses infecting these organisms have been described. Here, we present complete genomes for three distinct groups of viruses assembled from metagenomic sequence datasets highly enriched for MG-II. These novel viruses, which we denote magroviruses, possess double-stranded DNA genomes of 65 to 100 kilobases in size that encode a structural module characteristic of head-tailed viruses and, unusually for archaeal and bacterial viruses, a nearly complete replication apparatus of apparent archaeal origin. The newly identified magroviruses are widespread and abundant and therefore are likely to be major ecological agents. A novel viral group, magroviruses, likely infects marine group II archaea Magroviruses are highly abundant in oceanic surface waters worldwide Magroviruses have linear, double-stranded DNA genomes of about 100 kilobases Magroviruses encode a near complete replication apparatus of apparent archaeal origin
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Affiliation(s)
- Alon Philosof
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel.
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - José Flores-Uribe
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
| | - Itai Sharon
- Migal Galilee Research Institute, Kiryat Shmona 11016, Israel; Tel Hai College, Upper Galilee 12210, Israel
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Oded Béjà
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel.
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16
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Pramanik S, Kutzner A, Heese K. Livebearing or egg-laying mammals: 27 decisive nucleotides of FAM168. Biosci Trends 2017; 11:169-178. [PMID: 28381702 DOI: 10.5582/bst.2016.01252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In the present study, we determine comprehensive molecular phylogenetic relationships of the novel myelin-associated neurite-outgrowth inhibitor (MANI) gene across the entire eukaryotic lineage. Combined computational genomic and proteomic sequence analyses revealed MANI as one of the two members of the novel family with sequence similarity 168 member (FAM168) genes, consisting of FAM168A and FAM168B, having distinct genetic differences that illustrate diversification in its biological function and genetic taxonomy across the phylogenetic tree. Phylogenetic analyses based on coding sequences of these FAM168 genes revealed that they are paralogs and that the earliest emergence of these genes occurred in jawed vertebrates such as Callorhinchus milii. Surprisingly, these two genes are absent in other chordates that have a notochord at some stage in their lives, such as branchiostoma and tunicates. In the context of phylogenetic relationships among eukaryotic species, our results demonstrate the presence of FAM168 orthologs in vertebrates ranging from Callorhinchus milii to Homo sapiens, displaying distinct taxonomic clusters, comprised of fish, amphibians, reptiles, birds, and mammals. Analyses of individual FAM168 exons in our sample provide new insights into the molecular relationships between FAM168A and FAM168B (MANI) on the one hand and livebearing and egg-laying mammals on the other hand, demonstrating that a distinctive intermediate exon 4, comprised of 27 nucleotides, appears suddenly only in FAM168A and there in the livebearing mammals only but is absent from all other species including the egg-laying mammals.
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Affiliation(s)
- Subrata Pramanik
- Graduate School of Biomedical Science and Engineering, Hanyang University
| | - Arne Kutzner
- Department of Information Systems, College of Engineering, Hanyang University
| | - Klaus Heese
- Graduate School of Biomedical Science and Engineering, Hanyang University
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17
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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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Takemura M. Morphological and Taxonomic Properties of Tokyovirus, the First Marseilleviridae Member Isolated from Japan. Microbes Environ 2016; 31:442-448. [PMID: 27867160 PMCID: PMC5158117 DOI: 10.1264/jsme2.me16107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Members of the Marseilleviridae family are large DNA viruses with icosahedral particle structures that infect Acanthamoeba cells. The first Marseillevirus to be discovered was isolated in 2009. Since then, several other members of the Marseilleviridae family have been reported, including Lausannevirus, Senegalvirus, Cannes 8 virus, Insectomime virus, Tunisvirus, Melbournevirus, Port-Miou virus, and Brazilian Marseillevirus, which have been isolated from Europe, Africa, Australia, and South America. The morphological and genomic properties of a new Marseilleviridae family member, Tokyovirus, discovered in a water/soil sample from a Japanese river in Tokyo, were described in the present study. Tokyovirus possesses icosahedral particles of up to 200 nm in diameter, as revealed by a transmission electron microscopy (TEM) analysis, which form a giant virion factory in Acanthamoeba cells. A preliminary genome analysis predicted 487 coding sequences. A dot plot analysis and phylogenetic analysis using family B DNA polymerase, proliferating cell nuclear antigen (PCNA), and DNA-directed RNA polymerase alpha subunit genes revealed that Tokyovirus shares similarities with Marseillevirus, Melbournevirus, and Cannes 8 virus (Marseilleviridae subclade A), but not with Lausannevirus and Port-Miou virus (subclade B), Tunisvirus and Insectomime virus (subclade C), or Brazilian Marseillevirus (subclade D), suggesting that Tokyovirus has evolved separately from the previously described Marseilleviridae members.
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Affiliation(s)
- Masaharu Takemura
- Laboratory of Biology, Department of Liberal Arts, Faculty of Science, Tokyo University of Science (RIKADAI)
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Complete Genome Sequence of a New Megavirus Family Member Isolated from an Inland Water Lake for the First Time in India. GENOME ANNOUNCEMENTS 2016; 4:4/3/e00402-16. [PMID: 27313286 PMCID: PMC4911465 DOI: 10.1128/genomea.00402-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report here the isolation and complete genome sequencing of a large double-stranded DNA virus, Powai Lake megavirus, for the first time from India. The isolation of a large DNA virus with genome size >1 Mb from India further attests to the prevalence of Giant viruses in different environmental niches.
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Nicolas E, Golemis EA, Arora S. POLD1: Central mediator of DNA replication and repair, and implication in cancer and other pathologies. Gene 2016; 590:128-41. [PMID: 27320729 PMCID: PMC4969162 DOI: 10.1016/j.gene.2016.06.031] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/10/2016] [Accepted: 06/14/2016] [Indexed: 02/06/2023]
Abstract
The evolutionarily conserved human polymerase delta (POLD1) gene encodes the large p125 subunit which provides the essential catalytic activities of polymerase δ (Polδ), mediated by 5′–3′ DNA polymerase and 3′–5′ exonuclease moieties. POLD1 associates with three smaller subunits (POLD2, POLD3, POLD4), which together with Replication Factor C and Proliferating Nuclear Cell Antigen constitute the polymerase holoenzyme. Polδ function is essential for replication, with a primary role as the replicase for the lagging strand. Polδ also has an important proofreading ability conferred by the exonuclease activity, which is critical for ensuring replicative fidelity, but also serves to repair DNA lesions arising as a result of exposure to mutagens. Polδ has been shown to be important for multiple forms of DNA repair, including nucleotide excision repair, double strand break repair, base excision repair, and mismatch repair. A growing number of studies in the past decade have linked germline and sporadic mutations in POLD1 and the other subunits of Polδ with human pathologies. Mutations in Polδ in mice and humans lead to genomic instability, mutator phenotype and tumorigenesis. The advent of genome sequencing techniques has identified damaging mutations in the proofreading domain of POLD1 as the underlying cause of some inherited cancers, and suggested that mutations in POLD1 may influence therapeutic management. In addition, mutations in POLD1 have been identified in the developmental disorders of mandibular hypoplasia, deafness, progeroid features and lipodystrophy and atypical Werner syndrome, while changes in expression or activity of POLD1 have been linked to senescence and aging. Intriguingly, some recent evidence suggests that POLD1 function may also be altered in diabetes. We provide an overview of critical Polδ activities in the context of these pathologic conditions.
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Affiliation(s)
- Emmanuelle Nicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Erica A Golemis
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Sanjeevani Arora
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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21
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DNA repair genes in the Megavirales pangenome. Curr Opin Microbiol 2016; 31:94-100. [PMID: 27042991 DOI: 10.1016/j.mib.2016.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/21/2016] [Accepted: 03/21/2016] [Indexed: 12/12/2022]
Abstract
The order 'Megavirales' represents a group of eukaryotic viruses with a large genome encoding a few hundred up to two thousand five hundred genes. Several members of Megavirales possess genes involved in major DNA repair pathways. Some of these genes were likely inherited from an ancient virus world and some others were derived from the genomes of their hosts. Here we examine molecular phylogenies of key DNA repair enzymes in light of recent hypotheses on the origin of Megavirales, and propose that the last common ancestors of the individual families of the order Megavirales already possessed DNA repair functions to achieve and maintain a moderately large genome and that this repair capacity gradually increased, in a family-dependent manner, during their recent evolution.
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22
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Giant viruses and the origin of modern eukaryotes. Curr Opin Microbiol 2016; 31:44-49. [PMID: 26894379 DOI: 10.1016/j.mib.2016.02.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 01/28/2023]
Abstract
Several authors have suggested that viruses from the NucleoCytoplasmic Large DNA Viruses group (NCLDV) have played an important role in the origin of modern eukaryotes. Notably, the viral eukaryogenesis theory posits that the nucleus originated from an ancient NCLDV-related virus. Focusing on the viral factory instead of the virion adds credit to this hypothesis, but also suggests alternative scenarios. Beside a role in the emergence of the nucleus, ancient NCLDV may have provided new genes and/or chromosomes to the proto-eukaryotic lineage. Phylogenetic analyses suggest that NCLDV informational proteins, related to those of Archaea and Eukarya, were either recruited by ancient NCLDV from proto-eukaryotes and/or transferred to proto-eukaryotes, in agreement with the antiquity of NCLDV and their possible role in eukaryogenesis.
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23
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Correa AMS, Ainsworth TD, Rosales SM, Thurber AR, Butler CR, Vega Thurber RL. Viral Outbreak in Corals Associated with an In Situ Bleaching Event: Atypical Herpes-Like Viruses and a New Megavirus Infecting Symbiodinium. Front Microbiol 2016; 7:127. [PMID: 26941712 PMCID: PMC4761846 DOI: 10.3389/fmicb.2016.00127] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 01/25/2016] [Indexed: 12/03/2022] Open
Abstract
Previous studies of coral viruses have employed either microscopy or metagenomics, but few have attempted to comprehensively link the presence of a virus-like particle (VLP) to a genomic sequence. We conducted transmission electron microscopy imaging and virome analysis in tandem to characterize the most conspicuous viral types found within the dominant Pacific reef-building coral genus Acropora. Collections for this study inadvertently captured what we interpret as a natural outbreak of viral infection driven by aerial exposure of the reef flat coincident with heavy rainfall and concomitant mass bleaching. All experimental corals in this study had high titers of viral particles. Three of the dominant VLPs identified were observed in all tissue layers and budding out from the epidermis, including viruses that were ∼70, ∼120, and ∼150 nm in diameter; these VLPs all contained electron dense cores. These morphological traits are reminiscent of retroviruses, herpesviruses, and nucleocytoplasmic large DNA viruses (NCLDVs), respectively. Some 300–500 nm megavirus-like VLPs also were observed within and associated with dinoflagellate algal endosymbiont (Symbiodinium) cells. Abundant sequence similarities to a gammaretrovirus, herpesviruses, and members of the NCLDVs, based on a virome generated from five Acropora aspera colonies, corroborated these morphology-based identifications. Additionally sequence similarities to two diagnostic genes, a MutS and (based on re-annotation of sequences from another study) a DNA polymerase B gene, most closely resembled Pyramimonas orientalis virus, demonstrating the association of a cosmopolitan megavirus with Symbiodinium. We also identified several other virus-like particles in host tissues, along with sequences phylogenetically similar to circoviruses, phages, and filamentous viruses. This study suggests that viral outbreaks may be a common but previously undocumented component of natural bleaching events, particularly following repeated episodes of multiple environmental stressors.
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Affiliation(s)
- Adrienne M S Correa
- Department of Microbiology, Oregon State UniversityCorvallis, OR, USA; BioSciences at Rice, Rice UniversityHouston, TX, USA
| | - Tracy D Ainsworth
- ARC Centre of Excellence for Coral Reef Studies, James Cook University Townsville, QLD, Australia
| | | | - Andrew R Thurber
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University Corvallis, OR, USA
| | - Christopher R Butler
- Department of Microbiology, Oregon State UniversityCorvallis, OR, USA; Department of Viticulture and Enology, University of California at DavisDavis, CA, USA
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24
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Infection and Proliferation of Giant Viruses in Amoeba Cells. Uirusu 2016; 66:135-146. [PMID: 29081465 DOI: 10.2222/jsv.66.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Acanthamoeba polyphaga mimivirus, the first discovered giant virus with genome size and particle size much larger than previously discovered viruses, possesses several genes for translation and CRISPER Cas system-like defense mechanism against virophages, which co-infect amoeba cells with the giant virus and which inhibit giant virus proliferation. Mimiviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their stargate structure. After infection, giant virion factories (VFs) form in amoeba cytoplasm, followed by DNA replication and particle formation at peripheral regions of VF. Marseilleviruses, the smallest giant viruses, infect amoeba cells by phagocytosis or endocytosis, form larger VF than Mimivirus's VF in amoeba cytoplasm, and replicate their particles. Pandoraviruses found in 2013 have the largest genome size and particle size among all viruses ever found. Pandoraviruses infect amoeba cells by phagocytosis and release their DNA into amoeba cytoplasm through their mouth-like apical pores. The proliferation of Pandoraviruses occurs along with nucleus disruption. New virions form at the periphery of the region formerly occupied by the amoeba cell nucleus.
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