1
|
Van Etten JL, Agarkova IV, Dunigan DD, Shao Q, Fang Q. Emerging structure of chlorovirus PBCV-1. Virology 2025; 608:110552. [PMID: 40286469 DOI: 10.1016/j.virol.2025.110552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2025] [Revised: 04/16/2025] [Accepted: 04/17/2025] [Indexed: 04/29/2025]
Abstract
The large plaque-forming chloroviruses infect isolates of eukaryotic chlorella-like green algae. Initial cryo-electron microscopy (cryo-EM) studies revealed that PBCV-1 was icosahedral, with a multilaminate shell surrounding an electron-dense core, and that PBCV-1 particles measured about 1900 Å in diameter with a triangulation number of 169d. However, as described in this review cryo-EM procedures have improved and PBCV-1 is more complex than originally described. A five-fold symmetry reconstruction of cryo-EM images at 8.5 Å revealed that the virus contains a unique vertex with a spike-structure and an internal single lipid bi-layered membrane. Improvement to 3.5 Å resolution revealed that the capsid contains 30 virus-encoded proteins and that it contains six different types of capsomers. The outer surface of three of the six types of capsomers are attached to fiber structures.
Collapse
Affiliation(s)
- James L Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, USA, 68583-0900.
| | - Irina V Agarkova
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, USA, 68583-0900
| | - David D Dunigan
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, USA, 68583-0900
| | - Qianqian Shao
- School of Public Health (Shenzhen) Sun Yat-Sen University, Shenzhen, Guangdong, 518107, China
| | - Qianglin Fang
- School of Public Health (Shenzhen) Sun Yat-Sen University, Shenzhen, Guangdong, 518107, China
| |
Collapse
|
2
|
Carvalho JVRP, Carlson RM, Ghosh J, Queiroz VF, de Oliveira EG, Botelho BB, Filho CAC, Agarkova IV, McClung OW, Van Etten JL, Dunigan DD, Rodrigues RAL. Genomics and evolutionary analysis of Chlorella variabilis-infecting viruses demarcate criteria for defining species of giant viruses. J Virol 2024; 98:e0036124. [PMID: 39404263 PMCID: PMC11575271 DOI: 10.1128/jvi.00361-24] [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: 02/22/2024] [Accepted: 05/28/2024] [Indexed: 11/20/2024] Open
Abstract
Chloroviruses exhibit a close relationship with their hosts with the phenotypic aspect of their ability to form lytic plaques having primarily guided the taxonomy. However, with the isolation of viruses that are only able to complete their replication cycle in one strain of Chlorella variabilis, systematic challenges emerged. In this study, we described the genomic features of 53 new chlorovirus isolates and used them to elucidate part of the evolutionary history and taxonomy of this clade. Our analysis revealed new chloroviruses with the largest genomes to date (>400 kbp) and indicated that four genomic features are statistically different in the viruses that only infect the Syngen 2-3 strain of C. variabilis (OSy viruses). We found large regions of dissimilarity in the genomes of viruses PBCV-1 and OSy-NE5 when compared with the other genomes. These regions contained genes related to the interaction with the host cell machinery and viral capsid proteins, which provided insights into the evolution of the replicative and structural modules in these giant viruses. Phylogenetic analysis using hallmark genes of Nucleocytoviricota revealed that OSy-viruses evolved from the NC64A-viruses, possibly emerging as a result of the strict relationship with their hosts. Merging phylogenetics and nucleotide identity analyses, we propose strategies to demarcate viral species, resulting in seven new species of chloroviruses. Collectively, our results show how genomic data can be used as lines of evidence to demarcate viral species. Using the chloroviruses as a case study, we expect that similar initiatives will emerge using the basis exhibited here.IMPORTANCEChloroviruses are a group of giant viruses with long dsDNA genomes that infect different species of Chlorella-like green algae. They are host-specific, and some isolates can only replicate within a single strain of Chlorella variabilis. The genomics of these viruses is still poorly explored, and the characterization of new isolates provides important data on their genetic diversity and evolution. In this work, we describe 53 new chlorovirus genomes, including many isolated from alkaline lakes for the first time. Through comparative genomics and molecular phylogeny, we provide evidence of genomic gigantism in chloroviruses and show that a subset of viruses became highly specific for their hosts at a particular point in evolutionary history. We propose criteria to demarcate species of chloroviruses, paving the way for an update in the taxonomy of other groups of viruses. This study is a new and important piece in the complex puzzle of giant algal viruses.
Collapse
Affiliation(s)
- João Victor R. P. Carvalho
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Roger M. Carlson
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, USA
| | - Jayadri Ghosh
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, USA
| | - Victória F. Queiroz
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Ellen G. de Oliveira
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Bruna B. Botelho
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Clécio A. C. Filho
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Irina V. Agarkova
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, USA
| | - O. William McClung
- Department of Mathematics and Computer Science, Nebraska Wesleyan University, Lincoln, Nebraska, USA
| | - James L. Van Etten
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, USA
| | - David D. Dunigan
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, USA
| | - Rodrigo A. L. Rodrigues
- Laboratório de Vírus, Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| |
Collapse
|
3
|
Lievens EJP, Kühn S, Horas EL, Le Pennec G, Peter S, Petrosky AD, Künzel S, Feulner PGD, Becks L. High parasite diversity maintained after an alga-virus coevolutionary arms race. J Evol Biol 2024; 37:795-806. [PMID: 38699979 DOI: 10.1093/jeb/voae053] [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: 10/01/2023] [Revised: 02/27/2024] [Accepted: 05/02/2024] [Indexed: 05/05/2024]
Abstract
Arms race dynamics are a common outcome of host-parasite coevolution. While they can theoretically be maintained indefinitely, realistic arms races are expected to be finite. Once an arms race has ended, for example due to the evolution of a generalist-resistant host, the system may transition into coevolutionary dynamics that favour long-term diversity. In microbial experiments, host-parasite arms races often transition into a stable coexistence of generalist-resistant hosts, (semi-)susceptible hosts, and parasites. While long-term host diversity is implicit in these cases, parasite diversity is usually overlooked. In this study, we examined parasite diversity after the end of an experimental arms race between a unicellular alga (Chlorella variabilis) and its lytic virus (PBCV-1). First, we isolated virus genotypes from multiple time points from two replicate microcosms. A time-shift experiment confirmed that the virus isolates had escalating host ranges, i.e., that arms races had occurred. We then examined the phenotypic and genetic diversity of virus isolates from the post-arms race phase. Post-arms race virus isolates had diverse host ranges, survival probabilities, and growth rates; they also clustered into distinct genetic groups. Importantly, host range diversity was maintained throughout the post-arms race phase, and the frequency of host range phenotypes fluctuated over time. We hypothesize that this dynamic polymorphism was maintained by a combination of fluctuating selection and demographic stochasticity. Together with previous work in prokaryotic systems, our results link experimental observations of arms races to natural observations of long-term host and parasite diversity.
Collapse
Affiliation(s)
- Eva J P Lievens
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Samuel Kühn
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Elena L Horas
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Guénolé Le Pennec
- Department of Fish Ecology and Evolution, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Sarah Peter
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Azade D Petrosky
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Sven Künzel
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Philine G D Feulner
- Department of Fish Ecology and Evolution, EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Department of Biology, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Lutz Becks
- Aquatic Ecology and Evolution Group, Department of Biology, University of Konstanz, Konstanz, Germany
| |
Collapse
|
4
|
Homola M, Büttner CR, Füzik T, Křepelka P, Holbová R, Nováček J, Chaillet ML, Žák J, Grybchuk D, Förster F, Wilson WH, Schroeder DC, Plevka P. Structure and replication cycle of a virus infecting climate-modulating alga Emiliania huxleyi. SCIENCE ADVANCES 2024; 10:eadk1954. [PMID: 38598627 PMCID: PMC11006232 DOI: 10.1126/sciadv.adk1954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 03/06/2024] [Indexed: 04/12/2024]
Abstract
The globally distributed marine alga Emiliania huxleyi has cooling effect on the Earth's climate. The population density of E. huxleyi is restricted by Nucleocytoviricota viruses, including E. huxleyi virus 201 (EhV-201). Despite the impact of E. huxleyi viruses on the climate, there is limited information about their structure and replication. Here, we show that the dsDNA genome inside the EhV-201 virion is protected by an inner membrane, capsid, and outer membrane. EhV-201 virions infect E. huxleyi by using fivefold vertices to bind to and fuse the virus' inner membrane with the cell plasma membrane. Progeny virions assemble in the cytoplasm at the surface of endoplasmic reticulum-derived membrane segments. Genome packaging initiates synchronously with the capsid assembly and completes through an aperture in the forming capsid. The genome-filled capsids acquire an outer membrane by budding into intracellular vesicles. EhV-201 infection induces a loss of surface protective layers from E. huxleyi cells, which enables the continuous release of virions by exocytosis.
Collapse
Affiliation(s)
- Miroslav Homola
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Carina R. Büttner
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Tibor Füzik
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Pavel Křepelka
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Radka Holbová
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Jiří Nováček
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Marten L. Chaillet
- Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Jakub Žák
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Danyil Grybchuk
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Friedrich Förster
- Bijvoet Centre for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - William H. Wilson
- Marine Biological Association, Plymouth, UK
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | | | - Pavel Plevka
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| |
Collapse
|
5
|
Thomy J, Sanchez F, Prioux C, Yau S, Xu Y, Mak J, Sun R, Piganeau G, Yung CCM. Unveiling Prasinovirus diversity and host specificity through targeted enrichment in the South China Sea. ISME COMMUNICATIONS 2024; 4:ycae109. [PMID: 39296779 PMCID: PMC11408933 DOI: 10.1093/ismeco/ycae109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 07/16/2024] [Accepted: 08/27/2024] [Indexed: 09/21/2024]
Abstract
Unicellular green picophytoplankton from the Mamiellales order are pervasive in marine ecosystems and susceptible to infections by prasinoviruses, large double-stranded DNA viruses within the Nucleocytoviricota phylum. We developed a double-stranded DNA virus enrichment and shotgun sequencing method, and successfully assembled 80 prasinovirus genomes from 43 samples in the South China Sea. Our research delivered the first direct estimation of 94% accuracy in correlating genome similarity to host range. Stirkingly, our analyses uncovered unexpected host-switching across diverse algal lineages, challenging the existing paradigms of host-virus co-speciation and revealing the dynamic nature of viral evolution. We also detected six instances of horizontal gene transfer between prasinoviruses and their hosts, including a novel alternative oxidase. Additionally, diversifying selection on a major capsid protein suggests an ongoing co-evolutionary arms race. These insights not only expand our understanding of prasinovirus genomic diversity but also highlight the intricate evolutionary mechanisms driving their ecological success and shaping broader virus-host interactions in marine environments.
Collapse
Affiliation(s)
- Julie Thomy
- Sorbonne Université, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, F-66650 Banyuls/Mer, France
- Department of Oceanography, School of Ocean and Earth Science and Technology (SOEST), University of Hawai'i at Mānoa, Honolulu, HI 96822, United States
| | - Frederic Sanchez
- Sorbonne Université, CNRS, Biologie Intégrative des Organismes Marins (BIOM), UMR 7232, Observatoire Océanologique, F-66650 Banyuls/Mer, France
| | - Camille Prioux
- Sorbonne Université, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, F-66650 Banyuls/Mer, France
- Centre Scientifique de Monaco, 8 Quai Antoine 1er, Monaco, MC 98000, Principality of Monaco
| | - Sheree Yau
- Sorbonne Université, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, F-66650 Banyuls/Mer, France
| | - Yangbing Xu
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Julian Mak
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Ruixian Sun
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Gwenael Piganeau
- Sorbonne Université, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, F-66650 Banyuls/Mer, France
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Charmaine C M Yung
- Department of Ocean Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Hong Kong SAR, China
| |
Collapse
|
6
|
Lievens EJP, Agarkova IV, Dunigan DD, Van Etten JL, Becks L. Efficient assays to quantify the life history traits of algal viruses. Appl Environ Microbiol 2023; 89:e0165923. [PMID: 38092674 PMCID: PMC10734466 DOI: 10.1128/aem.01659-23] [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] [Received: 09/27/2023] [Accepted: 09/27/2023] [Indexed: 12/22/2023] Open
Abstract
IMPORTANCE Viruses play a crucial role in microbial ecosystems by liberating nutrients and regulating the growth of their hosts. These effects are governed by viral life history traits, i.e., by the traits determining viral reproduction and survival. Understanding these traits is essential to predicting viral effects, but measuring them is generally labor intensive. In this study, we present efficient methods to quantify the full life cycle of lytic viruses. We developed these methods for viruses infecting unicellular Chlorella algae but expect them to be applicable to other lytic viruses that can be quantified by flow cytometry. By making viral phenotypes accessible, our methods will support research into the diversity and ecological effects of microbial viruses.
Collapse
Affiliation(s)
- Eva J. P. Lievens
- Aquatic Ecology and Evolution Group, Limnological Institute, University of Konstanz, Konstanz, Germany
| | - Irina V. Agarkova
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - David D. Dunigan
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - James L. Van Etten
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Lutz Becks
- Aquatic Ecology and Evolution Group, Limnological Institute, University of Konstanz, Konstanz, Germany
| |
Collapse
|
7
|
Truchon AR, Chase EE, Gann ER, Moniruzzaman M, Creasey BA, Aylward FO, Xiao C, Gobler CJ, Wilhelm SW. Kratosvirus quantuckense: the history and novelty of an algal bloom disrupting virus and a model for giant virus research. Front Microbiol 2023; 14:1284617. [PMID: 38098665 PMCID: PMC10720644 DOI: 10.3389/fmicb.2023.1284617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 10/30/2023] [Indexed: 12/17/2023] Open
Abstract
Since the discovery of the first "giant virus," particular attention has been paid toward isolating and culturing these large DNA viruses through Acanthamoeba spp. bait systems. While this method has allowed for the discovery of plenty novel viruses in the Nucleocytoviricota, environmental -omics-based analyses have shown that there is a wealth of diversity among this phylum, particularly in marine datasets. The prevalence of these viruses in metatranscriptomes points toward their ecological importance in nutrient turnover in our oceans and as such, in depth study into non-amoebal Nucleocytoviricota should be considered a focal point in viral ecology. In this review, we report on Kratosvirus quantuckense (née Aureococcus anophagefferens Virus), an algae-infecting virus of the Imitervirales. Current systems for study in the Nucleocytoviricota differ significantly from this virus and its relatives, and a litany of trade-offs within physiology, coding potential, and ecology compared to these other viruses reveal the importance of K. quantuckense. Herein, we review the research that has been performed on this virus as well as its potential as a model system for algal-virus interactions.
Collapse
Affiliation(s)
- Alexander R Truchon
- Department of Microbiology, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Emily E Chase
- Department of Microbiology, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Eric R Gann
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
- Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
- Surgical Critical Care Initiative (SC2i), Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Mohammad Moniruzzaman
- Department of Marine Biology and Ecology, University of Miami, Miami, FL, United States
| | - Brooke A Creasey
- Department of Microbiology, University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Frank O Aylward
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Chuan Xiao
- Department of Chemistry and Biochemistry, The University of Texas at El Paso, El Paso, TX, United States
| | | | - Steven W Wilhelm
- Department of Microbiology, University of Tennessee, Knoxville, Knoxville, TN, United States
| |
Collapse
|
8
|
Ho HVN, Dunigan DD, Salsbery ME, Agarkova IV, Al Ameeli Z, Van Etten JL, DeLong JP. Viral Chemotaxis of Paramecium Bursaria Altered by Algal Endosymbionts. MICROBIAL ECOLOGY 2023; 86:2904-2909. [PMID: 37650927 DOI: 10.1007/s00248-023-02292-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/23/2023] [Indexed: 09/01/2023]
Abstract
Chemotaxis is widespread across many taxa and often aids resource acquisition or predator avoidance. Species interactions can modify the degree of movement facilitated by chemotaxis. In this study, we investigated the influence of symbionts on Paramecium bursaria's chemotactic behavior toward chloroviruses. To achieve this, we performed choice experiments using chlorovirus and control candidate attractors (virus stabilization buffer and pond water). We quantified the movement of Paramecia grown with or without algal and viral symbionts toward each attractor. All Paramecia showed some chemotaxis toward viruses, but cells without algae and viruses showed the most movement toward viruses. Thus, the endosymbiotic algae (zoochlorellae) appeared to alter the movement of Paramecia toward chloroviruses, but it was not clear that ectosymbiotic viruses (chlorovirus) also had this effect. The change in behavior was consistent with a change in swimming speed, but a change in attraction remains possible. The potential costs and benefits of chemotactic movement toward chloroviruses for either the Paramecia hosts or its symbionts remain unclear.
Collapse
Affiliation(s)
- Huy V N Ho
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-2083, USA
| | - David D Dunigan
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0722, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - Miranda E Salsbery
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-2083, USA
| | - Irina V Agarkova
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0722, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - Zeina Al Ameeli
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0722, USA
- Medical Technical Institutes, Middle Technical University, Baghdad, Iraq
| | - James L Van Etten
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0722, USA
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - John P DeLong
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-2083, USA.
| |
Collapse
|
9
|
de Aquino ILM, Barcelos MG, Machado TB, Serafim MSM, Abrahão JS. Surface fibrils on the particles of nucleocytoviruses: A review. Exp Biol Med (Maywood) 2023; 248:2045-2052. [PMID: 37955170 PMCID: PMC10800130 DOI: 10.1177/15353702231208410] [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: 11/14/2023] Open
Abstract
The capsid has a central role in viruses' life cycle. Although one of its major functions is to protect the viral genome, the capsid may be composed of elements that, at some point, promote interaction with host cells and trigger infection. Considering the scenario of multiple origins of viruses along the viral evolution, a substantial number of capsid shapes, sizes, and symmetries have been described. In this context, capsids of giant viruses (GV) that infect protists have drawn the attention of the scientific community, especially in the last 20 years, specifically for having bacterial-like dimensions with hundreds of different proteins and exclusive features. For instance, the surface fibrils present on the mimivirus capsid are one of the most intriguing features of the known virosphere. They are 150-nm-long structures attached to a 450-nm capsid, resulting in a particle with a hairy appearance. Surface fibrils have also been described in the capsids of other nucleocytoviruses, although they may differ substantially among them. In this mini review for non-experts, we compile the most important available information on surface fibrils of nucleocytoviruses, discussing their putative functions, composition, length, organization, and origins.
Collapse
Affiliation(s)
- Isabella Luiza Martins de Aquino
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Matheus Gomes Barcelos
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Talita Bastos Machado
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Mateus Sá Magalhães Serafim
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Jônatas Santos Abrahão
- Laboratório de Vírus, Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte 31270-901, Brazil
| |
Collapse
|
10
|
Iritani K, Nakanishi A, Nihei R, Sugitani S, Yamashita T. Development of Epoxy and Urethane Thermosetting Resin Using Chlorella sp. as Curing Agent for Materials with Low Environmental Impact. Polymers (Basel) 2023; 15:2968. [PMID: 37447612 DOI: 10.3390/polym15132968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/23/2023] [Accepted: 07/04/2023] [Indexed: 07/15/2023] Open
Abstract
In the current system, the disposal of plastic materials causes serious environmental pollution such as the generation of carbon dioxide and destruction of the ecosystem by micro-plastics. To solve this problem, bioplastics, biomass and biodegradable plastics have been developed. As part of our research, we have developed novel bioplastics called "cell-plastics", in which a unicellular green algal cell serves as a fundamental resource. The production of the cell-plastics would be expected to reduce environmental impact due to the usage of a natural product. Herein, to overcome the mechanical strength of cell-plastics, we used thermosetting epoxy and urethane resins containing Chlorella sp. as the green algae. We successfully fabricated thermosetting resins with a Chlorella sp. content of approximately 70 wt% or more. IR measurements revealed that the chemical structure of an epoxide or isocyanate monomer mixed with Chlorella sp. was modified, which suggests that the resins were hardened by the chemical reaction. In addition, we investigated the effect of thermosetting conditions such as temperature and compression for curing both resins. It was revealed that the Young's moduli and tensile strengths were controlled by thermosetting temperature and compression, whereas the elongation ratios of the resins were constant at low values regardless of the conditions.
Collapse
Affiliation(s)
- Kohei Iritani
- Department of Applied Chemistry, School of Engineering, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
- Research Center for Advanced Lignin-Based Materials, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
| | - Akihito Nakanishi
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
- Graduate School of Bionics, Computer and Media Sciences, Bionics Program, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
| | - Rinka Nihei
- Department of Applied Chemistry, School of Engineering, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
| | - Shiomi Sugitani
- Department of Applied Chemistry, School of Engineering, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
| | - Takashi Yamashita
- Department of Applied Chemistry, School of Engineering, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
- Research Center for Advanced Lignin-Based Materials, Tokyo University of Technology, 1404-1 Katakuramachi, Hachioji, Tokyo 192-0982, Japan
| |
Collapse
|
11
|
Esmael A, Agarkova IV, Dunigan DD, Zhou Y, Van Etten JL. Viral DNA Accumulation Regulates Replication Efficiency of Chlorovirus OSy-NE5 in Two Closely Related Chlorella variabilis Strains. Viruses 2023; 15:1341. [PMID: 37376640 DOI: 10.3390/v15061341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
Many chloroviruses replicate in Chlorella variabilis algal strains that are ex-endosymbionts isolated from the protozoan Paramecium bursaria, including the NC64A and Syngen 2-3 strains. We noticed that indigenous water samples produced a higher number of plaque-forming viruses on C. variabilis Syngen 2-3 lawns than on C. variabilis NC64A lawns. These observed differences led to the discovery of viruses that replicate exclusively in Syngen 2-3 cells, named Only Syngen (OSy) viruses. Here, we demonstrate that OSy viruses initiate infection in the restricted host NC64A by synthesizing some early virus gene products and that approximately 20% of the cells produce a small number of empty virus capsids. However, the infected cells did not produce infectious viruses because the cells were unable to replicate the viral genome. This is interesting because all previous attempts to isolate host cells resistant to chlorovirus infection were due to changes in the host receptor for the virus.
Collapse
Affiliation(s)
- Ahmed Esmael
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Botany and Microbiology Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Irina V Agarkova
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
| | - David D Dunigan
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
| | - You Zhou
- Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - James L Van Etten
- Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583, USA
- Department of Plant Pathology, University of Nebraska, Lincoln, NE 68583, USA
| |
Collapse
|
12
|
DeLong JP, Van Etten JL, Dunigan DD. Lessons from Chloroviruses: the Complex and Diverse Roles of Viruses in Food Webs. J Virol 2023; 97:e0027523. [PMID: 37133447 PMCID: PMC10231191 DOI: 10.1128/jvi.00275-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023] Open
Abstract
Viruses can have large effects on the ecological communities in which they occur. Much of this impact comes from the mortality of host cells, which simultaneously alters microbial community composition and causes the release of matter that can be used by other organisms. However, recent studies indicate that viruses may be even more deeply integrated into the functioning of ecological communities than their effect on nutrient cycling suggests. In particular, chloroviruses, which infect chlorella-like green algae that typically occur as endosymbionts, participate in three types of interactions with other species. Chlororviruses (i) can lure ciliates from a distance, using them as a vector; (ii) depend on predators for access to their hosts; and (iii) get consumed as a food source by, at least, a variety of protists. Therefore, chloroviruses both depend on and influence the spatial structures of communities as well as the flows of energy through those communities, driven by predator-prey interactions. The emergence of these interactions are an eco-evolutionary puzzle, given the interdependence of these species and the many costs and benefits that these interactions generate.
Collapse
Affiliation(s)
- John P. DeLong
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - James L. Van Etten
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln Nebraska, USA
| | - David D. Dunigan
- Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln Nebraska, USA
| |
Collapse
|
13
|
Kopylov AI, Zabotkina EA, Sazhin AF, Romanova N, Belyaev N, Drozdova A. Virioplankton and virus-induced mortality of prokaryotes in the Kara Sea (Arctic) in summer. PeerJ 2023; 11:e15457. [PMID: 37250716 PMCID: PMC10215763 DOI: 10.7717/peerj.15457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 05/03/2023] [Indexed: 05/31/2023] Open
Abstract
Among the Arctic seas, the largest volume of river runoff (~45% of the total river-water inflow into the Arctic Ocean) enters the Siberian Kara Sea. The viral communities of the Kara Sea are important for the functioning of the marine ecosystem. Studies of virus-prokaryote interactions on the Kara Sea shelf have been conducted only in spring and autumn. Here, we investigated the abundance of free viruses, viruses attached to prokaryotes, and pico-sized detrital particles; the morphology (shape and size) of the viruses, viral infection and virus-mediated mortality of prokaryotes in early summer, i.e., during a seasonal ice melting period and maximum inflow of river-water volumes with high concentrations of dissolved and suspended organic carbon. Seawater samples for microbial analyses were collected across the Kara Sea shelf zone on board the Norilskiy Nickel as a research platform from June 29 to July 15, 2018. Abundances of prokaryotes (range (0.6-25.3) × 105 cells mL-1) and free viruses (range (10-117) × 105 viruses mL-1) were correlated (r = 0.63, p = 0.005) with an average virus: prokaryote ratio of 23.9 ± 5.3. The abundance of free viruses and viral-mediated mortality of prokaryotes were significantly higher in early summer than in early spring and autumn. Free viruses with a capsid diameter of 16-304 nm were recorded in the examined water samples. Waters in the Kara Sea shelf contained high concentrations of suspended organic particles 0.25-4.0 µm in size (range (0.6-25.3) × 105 particles mL-1). The proportions of free viruses, viruses attached to prokaryotes, and viruses attached to pico-sized detrital particles were 89.8 ± 6.0%, 2.2 ± 0.6% and 8.0 ± 1.3%, respectively, of the total virioplankton abundance (on average (61.5 ± 6.2) × 105 viruses mL-1). Viruses smaller than 60 nm clearly dominated at all studied sites. The majority of free viruses were not tailed. We estimated that an average of 1.4% (range 0.4-3.5%) of the prokaryote community was visibly infected by viruses, suggesting that a significant proportion of prokaryotic secondary production, 11.4% on average (range 4.0-34.0%), was lost due to viral lysis. There was a negative correlation between the abundance of pico-sized detrital particles and the frequency of visibly infected prokaryotic cells: r = -0.67, p = 0.0008.
Collapse
Affiliation(s)
| | | | | | - Nadezda Romanova
- Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russia
| | - Nikolay Belyaev
- Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russia
| | - Anastasia Drozdova
- Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
14
|
Speciale I, Notaro A, Abergel C, Lanzetta R, Lowary TL, Molinaro A, Tonetti M, Van Etten JL, De Castro C. The Astounding World of Glycans from Giant Viruses. Chem Rev 2022; 122:15717-15766. [PMID: 35820164 PMCID: PMC9614988 DOI: 10.1021/acs.chemrev.2c00118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Indexed: 12/12/2022]
Abstract
Viruses are a heterogeneous ensemble of entities, all sharing the need for a suitable host to replicate. They are extremely diverse, varying in morphology, size, nature, and complexity of their genomic content. Typically, viruses use host-encoded glycosyltransferases and glycosidases to add and remove sugar residues from their glycoproteins. Thus, the structure of the glycans on the viral proteins have, to date, typically been considered to mimick those of the host. However, the more recently discovered large and giant viruses differ from this paradigm. At least some of these viruses code for an (almost) autonomous glycosylation pathway. These viral genes include those that encode the production of activated sugars, glycosyltransferases, and other enzymes able to manipulate sugars at various levels. This review focuses on large and giant viruses that produce carbohydrate-processing enzymes. A brief description of those harboring these features at the genomic level will be discussed, followed by the achievements reached with regard to the elucidation of the glycan structures, the activity of the proteins able to manipulate sugars, and the organic synthesis of some of these virus-encoded glycans. During this progression, we will also comment on many of the challenging questions on this subject that remain to be addressed.
Collapse
Affiliation(s)
- Immacolata Speciale
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
| | - Anna Notaro
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
- Centre
National de la Recherche Scientifique, Information Génomique
& Structurale, Aix-Marseille University, Unité Mixte de Recherche
7256, IMM, IM2B, 13288 Marseille, Cedex 9, France
| | - Chantal Abergel
- Centre
National de la Recherche Scientifique, Information Génomique
& Structurale, Aix-Marseille University, Unité Mixte de Recherche
7256, IMM, IM2B, 13288 Marseille, Cedex 9, France
| | - Rosa Lanzetta
- Department
of Chemical Sciences, University of Napoli, Via Cintia 4, 80126 Napoli, Italy
| | - Todd L. Lowary
- Institute
of Biological Chemistry, Academia Sinica, Academia Road, Section 2, Nangang 11529, Taipei, Taiwan
| | - Antonio Molinaro
- Department
of Chemical Sciences, University of Napoli, Via Cintia 4, 80126 Napoli, Italy
| | - Michela Tonetti
- Department
of Experimental Medicine and Center of Excellence for Biomedical Research, University of Genova, 16132 Genova, Italy
| | - James L. Van Etten
- Nebraska
Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900, United States
- Department
of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, United States
| | - Cristina De Castro
- Department
of Agricultural Sciences, University of
Napoli, Via Università
100, 80055 Portici, Italy
| |
Collapse
|
15
|
Molina-Grima E, García-Camacho F, Acién-Fernández FG, Sánchez-Mirón A, Plouviez M, Shene C, Chisti Y. Pathogens and predators impacting commercial production of microalgae and cyanobacteria. Biotechnol Adv 2021; 55:107884. [PMID: 34896169 DOI: 10.1016/j.biotechadv.2021.107884] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/25/2021] [Accepted: 12/02/2021] [Indexed: 02/09/2023]
Abstract
Production of phytoplankton (microalgae and cyanobacteria) in commercial raceway ponds and other systems is adversely impacted by phytoplankton pathogens, including bacteria, fungi and viruses. In addition, cultures are susceptible to productivity loss, or crash, through grazing by contaminating zooplankton such as protozoa, rotifers and copepods. Productivity loss and product contamination are also caused by otherwise innocuous invading phytoplankton that consume resources in competition with the species being cultured. This review is focused on phytoplankton competitors, pathogens and grazers of significance in commercial culture of microalgae and cyanobacteria. Detection and identification of these biological contaminants are discussed. Operational protocols for minimizing contamination, and methods of managing it, are discussed.
Collapse
Affiliation(s)
- Emilio Molina-Grima
- Department of Chemical Engineering, University of Almería, 04120 Almería, Spain
| | | | | | | | - Maxence Plouviez
- School of Food and Advanced Technology, Massey University, Private Bag 11 222, Palmerston North, New Zealand
| | - Carolina Shene
- Center for Biotechnology and Bioengineering (CeBiB), Center of Food Biotechnology and Bioseparations, BIOREN and Department of Chemical Engineering, Universidad de La Frontera, Francisco Salazar 01145, Temuco 4780000, Chile
| | - Yusuf Chisti
- School of Engineering, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
| |
Collapse
|
16
|
Noel EA, Weeks DP, Van Etten JL. Pursuit of chlorovirus genetic transformation and CRISPR/Cas9-mediated gene editing. PLoS One 2021; 16:e0252696. [PMID: 34673785 PMCID: PMC8530361 DOI: 10.1371/journal.pone.0252696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 09/29/2021] [Indexed: 11/18/2022] Open
Abstract
Genetic and molecular modifications of the large dsDNA chloroviruses, with genomes of 290 to 370 kb, would expedite studies to elucidate the functions of both identified and unidentified virus-encoded proteins. These plaque-forming viruses replicate in certain unicellular, eukaryotic chlorella-like green algae. However, to date, only a few of these algal species and virtually none of their viruses have been genetically manipulated due to lack of practical methods for genetic transformation and genome editing. Attempts at using Agrobacterium-mediated transfection of chlorovirus host Chlorella variabilis NC64A with a specially-designed binary vector resulted in successful transgenic cell selection based on expression of a hygromycin-resistance gene, initial expression of a green fluorescence gene and demonstration of integration of Agrobacterium T-DNA. However, expression of the integrated genes was soon lost. To develop gene editing tools for modifying specific chlorovirus CA-4B genes using preassembled Cas9 protein-sgRNA ribonucleoproteins (RNPs), we tested multiple methods for delivery of Cas9/sgRNA RNP complexes into infected cells including cell wall-degrading enzymes, electroporation, silicon carbide (SiC) whiskers, and cell-penetrating peptides (CPPs). In one experiment two independent virus mutants were isolated from macerozyme-treated NC64A cells incubated with Cas9/sgRNA RNPs targeting virus CA-4B-encoded gene 034r, which encodes a glycosyltransferase. Analysis of DNA sequences from the two mutant viruses showed highly targeted nucleotide sequence modifications in the 034r gene of each virus that were fully consistent with Cas9/RNP-directed gene editing. However, in ten subsequent experiments, we were unable to duplicate these results and therefore unable to achieve a reliable system to genetically edit chloroviruses. Nonetheless, these observations provide strong initial suggestions that Cas9/RNPs may function to promote editing of the chlorovirus genome, and that further experimentation is warranted and worthwhile.
Collapse
Affiliation(s)
- Eric A. Noel
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, United States of America
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Donald P. Weeks
- Department of Biochemistry, University of Nebraska, Lincoln, Nebraska, United States of America
| | - James L. Van Etten
- Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, United States of America
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, United States of America
| |
Collapse
|
17
|
Chaudhari HV, Inamdar MM, Kondabagil K. Scaling relation between genome length and particle size of viruses provides insights into viral life history. iScience 2021; 24:102452. [PMID: 34113814 PMCID: PMC8169800 DOI: 10.1016/j.isci.2021.102452] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/23/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
In terms of genome and particle sizes, viruses exhibit great diversity. With the discovery of several nucleocytoplasmic large DNA viruses (NCLDVs) and jumbo phages, the relationship between particle and genome sizes has emerged as an important criterion for understanding virus evolution. We use allometric scaling of capsid volume with the genome length of different groups of viruses to shed light on its relationship with virus life history. The allometric exponents for icosahedral dsDNA bacteriophages and NCDLVs were found to be 1 and 2, respectively, indicating that with increasing capsid size DNA packaging density remains the same in bacteriophages but decreases for NCLDVs. We argue that the exponents are largely shaped by their entry mechanism and capsid mechanical stability. We further show that these allometric size parameters are also intricately linked to the relative energy costs of translation and replication in viruses and can have further implications on viral life history. Capsid and genome size allometric exponent gives insights into viral life history The allometric exponent of NCLDVs is almost twice that of bacteriophages The exponent is largely shaped by the viral entry mechanism and capsid stability The relaxed genome size constraint allows large viruses to evolve greater autonomy
Collapse
Affiliation(s)
- Harshali V Chaudhari
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Mandar M Inamdar
- Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| |
Collapse
|
18
|
Sadeghi M, Tomaru Y, Ahola T. RNA Viruses in Aquatic Unicellular Eukaryotes. Viruses 2021; 13:v13030362. [PMID: 33668994 PMCID: PMC7996518 DOI: 10.3390/v13030362] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 12/24/2022] Open
Abstract
Increasing sequence information indicates that RNA viruses constitute a major fraction of marine virus assemblages. However, only 12 RNA virus species have been described, infecting known host species of marine single-celled eukaryotes. Eight of these use diatoms as hosts, while four are resident in dinoflagellate, raphidophyte, thraustochytrid, or prasinophyte species. Most of these belong to the order Picornavirales, while two are divergent and fall into the families Alvernaviridae and Reoviridae. However, a very recent study has suggested that there is extraordinary diversity in aquatic RNA viromes, describing thousands of viruses, many of which likely use protist hosts. Thus, RNA viruses are expected to play a major ecological role for marine unicellular eukaryotic hosts. In this review, we describe in detail what has to date been discovered concerning viruses with RNA genomes that infect aquatic unicellular eukaryotes.
Collapse
Affiliation(s)
- Mohammadreza Sadeghi
- Department of Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, 00014 Helsinki, Finland
- Correspondence: (M.S.); (T.A.)
| | - Yuji Tomaru
- Environment and Fisheries Applied Techniques Research Department, Fisheries Technology Institute, Fisheries Research and Education Agency, Hatsukaichi, Hiroshima 739-0452, Japan;
| | - Tero Ahola
- Department of Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, 00014 Helsinki, Finland
- Correspondence: (M.S.); (T.A.)
| |
Collapse
|
19
|
Hoshina R, Tsukii Y, Harumoto T, Suzaki T. Characterization of a green Stentor with symbiotic algae growing in an extremely oligotrophic environment and storing large amounts of starch granules in its cytoplasm. Sci Rep 2021; 11:2865. [PMID: 33536497 PMCID: PMC7859197 DOI: 10.1038/s41598-021-82416-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 12/30/2020] [Indexed: 01/30/2023] Open
Abstract
The genus Stentor is a relatively well-known ciliate owing to its lucid trumpet shape. Stentor pyriformis represents a green, short, and fat Stentor, but it is a little-known species. We investigated 124 ponds and wetlands in Japan and confirmed the presence of S. pyriformis at 23 locations. All these ponds were noticeably oligotrophic. With the improvement of oligotrophic culture conditions, we succeeded in long-term cultivation of three strains of S. pyriformis. The cytoplasm of S. piriformis contains a large number of 1-3 μm refractive granules that turn brown by Lugol's staining. The granules also show a typical Maltese-cross pattern by polarization microscopy, strongly suggesting that the granules are made of amylopectin-rich starch. By analyzing the algal rDNA, it was found that all S. pyriformis symbionts investigated in this study were Chlorella variabilis. This species is known as the symbiont of Paramecium bursaria and is physiologically specialized for endosymbiosis. Genetic discrepancies between C. variabilis of S. pyriformis and P. bursaria may indicate that algal sharing was an old incident. Having symbiotic algae and storing carbohydrate granules in the cytoplasm is considered a powerful strategy for this ciliate to withstand oligotrophic and cold winter environments in highland bogs.
Collapse
Affiliation(s)
- Ryo Hoshina
- grid.419056.f0000 0004 1793 2541Nagahama Institute of Bio-Science and Technology, Tamura 1266, Nagahama, Shiga 526-0829 Japan
| | - Yuuji Tsukii
- grid.257114.40000 0004 1762 1436Laboratory of Biological Science, Hosei University, 2-17-1 Fujimi, Chiyoda-ku, Tokyo 102-8160 Japan
| | - Terue Harumoto
- grid.174568.90000 0001 0059 3836Research Group of Biological Sciences, Division of Natural Sciences, Nara Women’s University, Kitauoya-Nishimachi, Nara 630-8506 Japan
| | - Toshinobu Suzaki
- grid.31432.370000 0001 1092 3077Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501 Japan
| |
Collapse
|
20
|
An epigenetic gene silencing pathway selectively acting on transgenic DNA in the green alga Chlamydomonas. Nat Commun 2020; 11:6269. [PMID: 33293544 PMCID: PMC7722844 DOI: 10.1038/s41467-020-19983-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/05/2020] [Indexed: 01/08/2023] Open
Abstract
Silencing of exogenous DNA can make transgene expression very inefficient. Genetic screens in the model alga Chlamydomonas have demonstrated that transgene silencing can be overcome by mutations in unknown gene(s), thus producing algal strains that stably express foreign genes to high levels. Here, we show that the silencing mechanism specifically acts on transgenic DNA. Once a permissive chromatin structure has assembled, transgene expression can persist even in the absence of mutations disrupting the silencing pathway. We have identified the gene conferring the silencing and show it to encode a sirtuin-type histone deacetylase. Loss of gene function does not appreciably affect endogenous gene expression. Our data suggest that transgenic DNA is recognized and then quickly inactivated by the assembly of a repressive chromatin structure composed of deacetylated histones. We propose that this mechanism may have evolved to provide protection from potentially harmful types of environmental DNA. Strong transgene suppression has been observed in Chlamydomonas reinhardtii, but the underlying mechanism is unknown. Here, the authors identify a sirtuin-type histone deacetylase that selectively acts on transgenic DNA to repress gene expression by assembling a repressive chromatin structure composed of deacetylated histones.
Collapse
|
21
|
Temperate infection in a virus-host system previously known for virulent dynamics. Nat Commun 2020; 11:4626. [PMID: 32934228 PMCID: PMC7493887 DOI: 10.1038/s41467-020-18078-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/28/2020] [Indexed: 12/15/2022] Open
Abstract
The blooming cosmopolitan coccolithophore Emiliania huxleyi and its viruses (EhVs) are a model for density-dependent virulent dynamics. EhVs commonly exhibit rapid viral reproduction and drive host death in high-density laboratory cultures and mesocosms that simulate blooms. Here we show that this system exhibits physiology-dependent temperate dynamics at environmentally relevant E. huxleyi host densities rather than virulent dynamics, with viruses switching from a long-term non-lethal temperate phase in healthy hosts to a lethal lytic stage as host cells become physiologically stressed. Using this system as a model for temperate infection dynamics, we present a template to diagnose temperate infection in other virus-host systems by integrating experimental, theoretical, and environmental approaches. Finding temperate dynamics in such an established virulent host-virus model system indicates that temperateness may be more pervasive than previously considered, and that the role of viruses in bloom formation and decline may be governed by host physiology rather than by host-virus densities.
Collapse
|
22
|
Coy SR, Gann ER, Papoulis SE, Holder ME, Ajami NJ, Petrosino JF, Zinser ER, Van Etten JL, Wilhelm SW. SMRT Sequencing of Paramecium Bursaria Chlorella Virus-1 Reveals Diverse Methylation Stability in Adenines Targeted by Restriction Modification Systems. Front Microbiol 2020; 11:887. [PMID: 32508769 PMCID: PMC7248222 DOI: 10.3389/fmicb.2020.00887] [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: 02/04/2020] [Accepted: 04/16/2020] [Indexed: 12/31/2022] Open
Abstract
Chloroviruses (family Phycodnaviridae) infect eukaryotic, freshwater, unicellular green algae. A unique feature of these viruses is an abundance of DNA methyltransferases, with isolates dedicating up to 4.5% of their protein coding potential to these genes. This diversity highlights just one of the long-standing values of the chlorovirus model system; where group-wide epigenomic characterization might begin to elucidate the function(s) of DNA methylation in large dsDNA viruses. We characterized DNA modifications in the prototype chlorovirus, PBCV-1, using single-molecule real time (SMRT) sequencing (aka PacBio). Results were compared to total available sites predicted in silico based on DNA sequence alone. SMRT-software detected N6-methyl-adenine (m6A) at GATC and CATG recognition sites, motifs previously shown to be targeted by PBCV-1 DNA methyltransferases M.CviAI and M. CviAII, respectively. At the same time, PacBio analyses indicated that 10.9% of the PBCV-1 genome had large interpulse duration ratio (ipdRatio) values, the primary metric for DNA modification identification. These events represent 20.6x more sites than can be accounted for by all available adenines in GATC and CATG motifs, suggesting base or backbone modifications other than methylation might be present. To define methylation stability, we cross-compared methylation status of each GATC and CATG sequence in three biological replicates and found ∼81% of sites were stably methylated, while ∼2% consistently lack methylation. The remaining 17% of sites were stochastically methylated. When methylation status was analyzed for both strands of each target, we show that palindromes existed in completely non-methylated states, fully-methylated states, or hemi-methylated states, though GATC sites more often lack methylation than CATG sequences. Given that both sequences are targeted by not just methyltransferases, but by restriction endonucleases that are together encoded by PBCV-1 as virus-originating restriction modification (RM) systems, there is strong selective pressure to modify all target sites. The finding that most instances of non-methylation are associated with hemi-methylation is congruent with observations that hemi-methylated palindromes are resistant to cleavage by restriction endonucleases. However, sites where hemi-methylation is conserved might represent a unique regulatory function for PBCV-1. This study serves as a baseline for future investigation into the epigenomics of chloroviruses and their giant virus relatives.
Collapse
Affiliation(s)
- Samantha R. Coy
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
- BioSciences at Rice, Rice University, Houston, TX, United States
| | - Eric R. Gann
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Spiridon E. Papoulis
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Michael E. Holder
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Nadim J. Ajami
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Joseph F. Petrosino
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX, United States
| | - Erik R. Zinser
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - James L. Van Etten
- Department of Plant Pathology and the Nebraska Center for Virology, University of Nebraska, Lincoln, NE, United States
| | - Steven W. Wilhelm
- Department of Microbiology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| |
Collapse
|
23
|
Yau S, Krasovec M, Benites LF, Rombauts S, Groussin M, Vancaester E, Aury JM, Derelle E, Desdevises Y, Escande ML, Grimsley N, Guy J, Moreau H, Sanchez-Brosseau S, van de Peer Y, Vandepoele K, Gourbiere S, Piganeau G. Virus-host coexistence in phytoplankton through the genomic lens. SCIENCE ADVANCES 2020; 6:eaay2587. [PMID: 32270031 PMCID: PMC7112755 DOI: 10.1126/sciadv.aay2587] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 01/09/2020] [Indexed: 05/02/2023]
Abstract
Virus-microbe interactions in the ocean are commonly described by "boom and bust" dynamics, whereby a numerically dominant microorganism is lysed and replaced by a virus-resistant one. Here, we isolated a microalga strain and its infective dsDNA virus whose dynamics are characterized instead by parallel growth of both the microalga and the virus. Experimental evolution of clonal lines revealed that this viral production originates from the lysis of a minority of virus-susceptible cells, which are regenerated from resistant cells. Whole-genome sequencing demonstrated that this resistant-susceptible switch involved a large deletion on one chromosome. Mathematical modeling explained how the switch maintains stable microalga-virus population dynamics consistent with their observed growth pattern. Comparative genomics confirmed an ancient origin of this "accordion" chromosome despite a lack of sequence conservation. Together, our results show how dynamic genomic rearrangements may account for a previously overlooked coexistence mechanism in microalgae-virus interactions.
Collapse
Affiliation(s)
- Sheree Yau
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain
- Corresponding author. (G.P.); (S.Y.)
| | - Marc Krasovec
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - L. Felipe Benites
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Stephane Rombauts
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
| | - Mathieu Groussin
- Department of Biological Engineering, Massachusetts Institute of Technology, 500 Technology Square NE47-378, Cambridge, MA 02139, USA
| | - Emmelien Vancaester
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
| | - Jean-Marc Aury
- Genoscope, Institut de biologie François Jacob, Commissariat à l’Energie Atomique (CEA), Université Paris-Saclay, Evry, France
| | - Evelyne Derelle
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
- Univ. Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzane, France
| | - Yves Desdevises
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Marie-Line Escande
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Nigel Grimsley
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Julie Guy
- Genoscope, Institut de biologie François Jacob, Commissariat à l’Energie Atomique (CEA), Université Paris-Saclay, Evry, France
| | - Hervé Moreau
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Sophie Sanchez-Brosseau
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
| | - Yves van de Peer
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0028, South Africa
| | - Klaas Vandepoele
- Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, Technologiepark-Zwijnaarde 71, 9052 Ghent, Belgium
| | - Sebastien Gourbiere
- Laboratoire Génome et Développement des Plantes, Université de Perpignan Via Domitia, UMR 5096, 52 Avenue Paul Alduy, 66860 Perpignan, France
| | - Gwenael Piganeau
- Sorbonne Université, CNRS, UMR 7232 Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls-sur-Mer, France
- Corresponding author. (G.P.); (S.Y.)
| |
Collapse
|
24
|
Van Etten JL, Agarkova IV, Dunigan DD. Chloroviruses. Viruses 2019; 12:E20. [PMID: 31878033 PMCID: PMC7019647 DOI: 10.3390/v12010020] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/13/2019] [Accepted: 12/15/2019] [Indexed: 12/20/2022] Open
Abstract
Chloroviruses are large dsDNA, plaque-forming viruses that infect certain chlorella-like green algae; the algae are normally mutualistic endosymbionts of protists and metazoans and are often referred to as zoochlorellae. The viruses are ubiquitous in inland aqueous environments throughout the world and occasionally single types reach titers of thousands of plaque-forming units per ml of native water. The viruses are icosahedral in shape with a spike structure located at one of the vertices. They contain an internal membrane that is required for infectivity. The viral genomes are 290 to 370 kb in size, which encode up to 16 tRNAs and 330 to ~415 proteins, including many not previously seen in viruses. Examples include genes encoding DNA restriction and modification enzymes, hyaluronan and chitin biosynthetic enzymes, polyamine biosynthetic enzymes, ion channel and transport proteins, and enzymes involved in the glycan synthesis of the virus major capsid glycoproteins. The proteins encoded by many of these viruses are often the smallest or among the smallest proteins of their class. Consequently, some of the viral proteins are the subject of intensive biochemical and structural investigation.
Collapse
Affiliation(s)
- James L. Van Etten
- Department of Plant Pathology, Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, USA; (I.V.A.); (D.D.D.)
| | | | | |
Collapse
|
25
|
Contributions of the microbial community to algal biomass and biofuel productivity in a wastewater treatment lagoon system. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101461] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
26
|
Viruses of Eukaryotic Algae: Diversity, Methods for Detection, and Future Directions. Viruses 2018; 10:v10090487. [PMID: 30208617 PMCID: PMC6165237 DOI: 10.3390/v10090487] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/04/2018] [Accepted: 09/07/2018] [Indexed: 11/16/2022] Open
Abstract
The scope for ecological studies of eukaryotic algal viruses has greatly improved with the development of molecular and bioinformatic approaches that do not require algal cultures. Here, we review the history and perceived future opportunities for research on eukaryotic algal viruses. We begin with a summary of the 65 eukaryotic algal viruses that are presently in culture collections, with emphasis on shared evolutionary traits (e.g., conserved core genes) of each known viral type. We then describe how core genes have been used to enable molecular detection of viruses in the environment, ranging from PCR-based amplification to community scale "-omics" approaches. Special attention is given to recent studies that have employed network-analyses of -omics data to predict virus-host relationships, from which a general bioinformatics pipeline is described for this type of approach. Finally, we conclude with acknowledgement of how the field of aquatic virology is adapting to these advances, and highlight the need to properly characterize new virus-host systems that may be isolated using preliminary molecular surveys. Researchers can approach this work using lessons learned from the Chlorella virus system, which is not only the best characterized algal-virus system, but is also responsible for much of the foundation in the field of aquatic virology.
Collapse
|
27
|
Bachy C, Charlesworth CJ, Chan AM, Finke JF, Wong CH, Wei CL, Sudek S, Coleman ML, Suttle CA, Worden AZ. Transcriptional responses of the marine green alga Micromonas pusilla and an infecting prasinovirus under different phosphate conditions. Environ Microbiol 2018; 20:2898-2912. [PMID: 29749714 DOI: 10.1111/1462-2920.14273] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/06/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022]
Abstract
Prasinophytes are widespread marine algae for which responses to nutrient limitation and viral infection are not well understood. We studied the picoprasinophyte, Micromonas pusilla, grown under phosphate-replete (0.65 ± 0.07 d-1 ) and 10-fold lower (low)-phosphate (0.11 ± 0.04 d-1 ) conditions, and infected by the phycodnavirus MpV-SP1. Expression of 17% of Micromonas genes in uninfected cells differed by >1.5-fold (q < 0.01) between nutrient conditions, with genes for P-metabolism and the uniquely-enriched Sel1-like repeat (SLR) family having higher relative transcript abundances, while phospholipid-synthesis genes were lower in low-P than P-replete. Approximately 70% (P-replete) and 30% (low-P) of cells were lysed 24 h post-infection, and expression of ≤5.8% of host genes changed relative to uninfected treatments. Host genes for CAZymes and glycolysis were activated by infection, supporting importance in viral production, which was significantly lower in slower growing (low-P) hosts. All MpV-SP1 genes were expressed, and our analyses suggest responses to differing host-phosphate backgrounds involve few viral genes, while the temporal program of infection involves many more, and is largely independent of host-phosphate background. Our study (i) identifies genes previously unassociated with nutrient acclimation or viral infection, (ii) provides insights into the temporal program of prasinovirus gene expression by hosts and (iii) establishes cell biological aspects of an ecologically important host-prasinovirus system that differ from other marine algal-virus systems.
Collapse
Affiliation(s)
- Charles Bachy
- Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA
| | - Christina J Charlesworth
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Amy M Chan
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Jan F Finke
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Chee-Hong Wong
- Lawrence Berkeley National Laboratory, Sequencing Technology Group, Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Chia-Lin Wei
- Lawrence Berkeley National Laboratory, Sequencing Technology Group, Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Sebastian Sudek
- Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA
| | - Maureen L Coleman
- Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Curtis A Suttle
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Toronto, M5G 1Z8, Canada.,Departments of Botany, and Microbiology & Immunology, and Institute of Oceans & Fisheries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Alexandra Z Worden
- Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, USA.,Integrated Microbial Biodiversity Program, Canadian Institute for Advanced Research, Toronto, M5G 1Z8, Canada
| |
Collapse
|
28
|
Is the Virus Important? And Some Other Questions. Viruses 2018; 10:v10080442. [PMID: 30126254 PMCID: PMC6116253 DOI: 10.3390/v10080442] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/14/2018] [Accepted: 08/15/2018] [Indexed: 11/22/2022] Open
Abstract
The motivation for focusing on a specific virus is often its importance in terms of impact on human interests. The chlorella viruses are a notable exception and 40 years of research has made them the undisputed model system for large icosahedral dsDNA viruses infecting eukaryotes. Their status has changed from inconspicuous and rather odd with no ecological relevance to being the Phycodnaviridae type strain possibly affecting humans and human cognitive functioning in ways that remain to be understood. The Van Etten legacy is the backbone for research on Phycodnaviridae. After highlighting some of the peculiarities of chlorella viruses, we point to some issues and questions related to the viruses we choose for our research, our prejudices, what we are still missing, and what we should be looking for.
Collapse
|
29
|
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: 4.1] [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.
Collapse
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.
| |
Collapse
|
30
|
Predators catalyze an increase in chloroviruses by foraging on the symbiotic hosts of zoochlorellae. Proc Natl Acad Sci U S A 2016; 113:13780-13784. [PMID: 27821770 DOI: 10.1073/pnas.1613843113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Virus population growth depends on contacts between viruses and their hosts. It is often unclear how sufficient contacts are made between viruses and their specific hosts to generate spikes in viral abundance. Here, we show that copepods, acting as predators, can bring aquatic viruses and their algal hosts into contact. Specifically, predation of the protist Paramecium bursaria by copepods resulted in a >100-fold increase in the number of chloroviruses in 1 d. Copepod predation can be seen as an ecological "catalyst" by increasing contacts between chloroviruses and their hosts, zoochlorellae (endosymbiotic algae that live within paramecia), thereby facilitating viral population growth. When feeding, copepods passed P. bursaria through their digestive tract only partially digested, releasing endosymbiotic algae that still supported viral reproduction and resulting in a virus population spike. A simple predator-prey model parameterized for copepods consuming protists generates cycle periods for viruses consistent with those observed in natural ponds. Food webs are replete with similar symbiotic organisms, and we suspect the predator catalyst mechanism is capable of generating blooms for other endosymbiont-targeting viruses.
Collapse
|
31
|
Andriolo JM, Rossi RJ, McConnell CA, Connors BI, Trout KL, Hailer MK, Pedulla ML, Skinner JL. Influence of Iron-Doped Apatite Nanoparticles on Viral Infection Examined in Bacterial Versus Algal Systems. IEEE Trans Nanobioscience 2016; 15:908-916. [PMID: 27775532 DOI: 10.1109/tnb.2016.2619349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Centers for Disease Control and Prevention have estimated that each year, two million people in the United States become infected with antibiotic-resistant bacteria, of which, approximately 23000 die as a direct result of these infections. Phage therapy, or the treatment of bacterial infection by specific, antagonistic viruses, provides one alternative to traditional antibiotics. Bacteriophages, or phages, are bacteria-specific viruses that possess biological traits that allow for not only the removal of bacterial infection, but also the evasion of bacterial resistance, which renders antibiotics ineffective. Previous research has shown the addition of iron-doped apatite nanoparticles (IDANPs) to bacteria prior to phage exposure results in increased bacterial plaques in vitro. Coupled with the biocompatible nature of apatite, these results provide promise for future use of IDANPs as adjuvants to phage therapy along with anti-bacterial applications yet to be explored. Although IDANP enhancement of phage infection has been replicated many times in gram-positive and gram-negative prokaryotic hosts as well as with the utilization of both RNA and DNA viruses, the specific mechanisms involved remain elusive. To further understand increased phage infections in a prokaryotic system, and to evaluate the safety of IDANPs as a treatment used in a eukaryotic system, we have replicated plaque assay experiments in an algal system using Chlorella variabilis NC64A and its virus, Paramecium bursaria chlorella virus 1 (PBCV-1). Statistical modeling was used to evaluate alteration in numbers of plaques observed after viral introduction in IDANP-exposed versus non-IDANP-exposed bacterial and algal cell cultures. While IDANPs synthesized between 25°C-45°C and doped with 30% iron have been shown to influence dramatic increases in phage-induced bacterial death, experiments replicated in an algal system indicated viral infections do not increase when C. variabilis cells are pre-exposed to IDANPs. It is essential to potential use of IDANPs as an antibacterial adjuvant that IDANPs do not increase viral infection of eukaryotic host cells during treatment.
Collapse
|
32
|
Royce C, Pardy R. Endotoxin-like properties of an extract from a symbiotic, eukaryotic Chlorella-like green alga. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/096805199600300601] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Hot phenol-water extraction of axenic cultures of the eukaryotic symbiotic green alga, Chlorella, yielded a substance having many of the characteristics of bacterial endotoxin or lipopolysaccharide (LPS). This material caused gelation of extracts of Limulus amoebocyte lysate at concentrations similar to those manifest by LPS from Gram-negative enteric bacteria. Activity was reduced substantially by incubation with polymyxin B sulfate and Limulus endotoxin-neutralizing protein (ENP), both of which have been shown to neutralize the biological activity of LPS from Gram-negative enteric bacteria. Partially purified biologically active material was found to contain 3-deoxy-D-manno-octulosonic acid (KDO), a sugar characteristically found in LPS. Acid hydrolysis of the Chlorella extract yielded a precipitate with characteristics of lipid A. Further hydrolysis followed by methylation yielded products with retention times on gas chromatography indistinguishable from 3-hydroxylauric and 3-hydroxymyristic acids. Results of transmission electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining are consistent with those obtained with purified enteric bacterial LPS. Exhaustive precautions against potential experimental artifacts due to cross contamination by endotoxin from Gram-negative bacteria, either in algal cultures or associated with glassware allowed the conclusion that the green alga, Chlorella (strain NC64A) synthesizes a LPS-like molecule.
Collapse
Affiliation(s)
- C.L. Royce
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - R.L. Pardy
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| |
Collapse
|
33
|
Rousvoal S, Bouyer B, López-Cristoffanini C, Boyen C, Collén J. Mutant swarms of a totivirus-like entities are present in the red macroalga Chondrus crispus and have been partially transferred to the nuclear genome. JOURNAL OF PHYCOLOGY 2016; 52:493-504. [PMID: 27151076 DOI: 10.1111/jpy.12427] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/15/2016] [Indexed: 06/05/2023]
Abstract
Chondrus crispus Stackhouse (Gigartinales) is a red seaweed found on North Atlantic rocky shores. Electrophoresis of RNA extracts showed a prominent band with a size of around 6,000 bp. Sequencing of the band revealed several sequences with similarity to totiviruses, double-stranded RNA viruses that normally infect fungi. This virus-like entity was named C. crispus virus (CcV). It should probably be regarded as an extreme viral quasispecies or a mutant swarm since low identity (<65%) was found between sequences. Totiviruses typically code for two genes: one capsid gene (gag) and one RNA-dependent RNA polymerase gene (pol) with a pseudoknot structure between the genes. Both the genes and the intergenic structures were found in the CcV sequences. A nonidentical gag gene was also found in the nuclear genome of C. crispus, with associated expressed sequence tags (EST) and upstream regulatory features. The gene was presumably horizontally transferred from the virus to the alga. Similar dsRNA bands were seen in extracts from different life cycle stages of C. crispus and from all geographic locations tested. In addition, similar bands were also observed in RNA extractions from other red algae; however, the significance of this apparently widespread phenomenon is unknown. Neither phenotype caused by the infection nor any virus particles or capsid proteins were identified; thus, the presence of viral particles has not been validated. These findings increase the known host range of totiviruses to include marine red algae.
Collapse
Affiliation(s)
- Sylvie Rousvoal
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688, Roscoff Cedex, France
- UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, UPMC Univ Paris 06, CS 90074, 29688, Roscoff Cedex, France
| | - Betty Bouyer
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688, Roscoff Cedex, France
- UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, UPMC Univ Paris 06, CS 90074, 29688, Roscoff Cedex, France
| | - Camilo López-Cristoffanini
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688, Roscoff Cedex, France
- UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, UPMC Univ Paris 06, CS 90074, 29688, Roscoff Cedex, France
| | - Catherine Boyen
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688, Roscoff Cedex, France
- UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, UPMC Univ Paris 06, CS 90074, 29688, Roscoff Cedex, France
| | - Jonas Collén
- CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, 29688, Roscoff Cedex, France
- UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Universités, UPMC Univ Paris 06, CS 90074, 29688, Roscoff Cedex, France
| |
Collapse
|
34
|
Klose T, Reteno DG, Benamar S, Hollerbach A, Colson P, La Scola B, Rossmann MG. Structure of faustovirus, a large dsDNA virus. Proc Natl Acad Sci U S A 2016; 113:6206-11. [PMID: 27185929 PMCID: PMC4896704 DOI: 10.1073/pnas.1523999113] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many viruses protect their genome with a combination of a protein shell with or without a membrane layer. Here we describe the structure of faustovirus, the first DNA virus (to our knowledge) that has been found to use two protein shells to encapsidate and protect its genome. The crystal structure of the major capsid protein, in combination with cryo-electron microscopy structures of two different maturation stages of the virus, shows that the outer virus shell is composed of a double jelly-roll protein that can be found in many double-stranded DNA viruses. The structure of the repeating hexameric unit of the inner shell is different from all other known capsid proteins. In addition to the unique architecture, the region of the genome that encodes the major capsid protein stretches over 17,000 bp and contains a large number of introns and exons. This complexity might help the virus to rapidly adapt to new environments or hosts.
Collapse
Affiliation(s)
- Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Dorine G Reteno
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Unité Mixte de Recherche 63, CNRS 7278, Institut de Recherche pour le Développement 198, INSERM U1095, Aix-Marseille Université, 13005 Marseille, France
| | - Samia Benamar
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Unité Mixte de Recherche 63, CNRS 7278, Institut de Recherche pour le Développement 198, INSERM U1095, Aix-Marseille Université, 13005 Marseille, France
| | - Adam Hollerbach
- Department of Chemistry, Purdue University, West Lafayette, IN 47907
| | - Philippe Colson
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Unité Mixte de Recherche 63, CNRS 7278, Institut de Recherche pour le Développement 198, INSERM U1095, Aix-Marseille Université, 13005 Marseille, France
| | - Bernard La Scola
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Unité Mixte de Recherche 63, CNRS 7278, Institut de Recherche pour le Développement 198, INSERM U1095, Aix-Marseille Université, 13005 Marseille, France
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907;
| |
Collapse
|
35
|
Long AM, Short SM. Seasonal determinations of algal virus decay rates reveal overwintering in a temperate freshwater pond. ISME JOURNAL 2016; 10:1602-12. [PMID: 26943625 DOI: 10.1038/ismej.2015.240] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 10/30/2015] [Accepted: 11/18/2015] [Indexed: 11/09/2022]
Abstract
To address questions about algal virus persistence (i.e., continued existence) in the environment, rates of decay of infectivity for two viruses that infect Chlorella-like algae, ATCV-1 and CVM-1, and a virus that infects the prymnesiophyte Chrysochromulina parva, CpV-BQ1, were estimated from in situ incubations in a temperate, seasonally frozen pond. A series of experiments were conducted to estimate rates of decay of infectivity in all four seasons with incubations lasting 21 days in spring, summer and autumn, and 126 days in winter. Decay rates observed across this study were relatively low compared with previous estimates obtained for other algal viruses, and ranged from 0.012 to 11% h(-1). Overall, the virus CpV-BQ1 decayed most rapidly whereas ATCV-1 decayed most slowly, but for all viruses the highest decay rates were observed during the summer and the lowest were observed during the winter. Furthermore, the winter incubations revealed the ability of each virus to overwinter under ice as ATCV-1, CVM-1 and CpV-BQ1 retained up to 48%, 19% and 9% of their infectivity after 126 days, respectively. The observed resilience of algal viruses in a seasonally frozen freshwater pond provides a mechanism that can support the maintenance of viral seed banks in nature. However, the high rates of decay observed in the summer demonstrate that virus survival and therefore environmental persistence can be subject to seasonal bottlenecks.
Collapse
Affiliation(s)
- Andrew M Long
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Steven M Short
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| |
Collapse
|
36
|
Peduzzi P. Virus ecology of fluvial systems: a blank spot on the map? Biol Rev Camb Philos Soc 2015; 91:937-949. [PMID: 26105126 PMCID: PMC5055098 DOI: 10.1111/brv.12202] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 05/21/2015] [Accepted: 05/27/2015] [Indexed: 11/29/2022]
Abstract
The ecology of viruses has been studied only in a limited number of rivers and streams. In light of a recent re-appraisal of the global fluvial surface area, issues such as abundance and production, host mortality and the influence of suspended particles and biofilms are addressed. Viral life cycles, potential impacts of viruses on water biochemistry and carbon flow, and viral diversity are considered. Variability in trophic levels along with the heterogeneous nature and hydrological dynamics of fluvial environments suggest a prevailingly physical control of virus-related processes under lotic conditions and more biological control under lentic conditions. Viral lysis likely contributes to a pool of rapidly cycling carbon in environments typically characterized by high proportions of recalcitrant terrestrial carbon. On average, 33.6% (equalling 0.605 Pg C year-1 ) of the globally respired carbon from fluvial systems may pass through a viral loop. Virus distribution and the proportion of organic material in horizontal transport versus processes in retention zones remain to be determined in detail. The need for up-scaling the contribution of virus-related processes in fluvial systems is of global relevance. Further, the role of climate change and the effect of anthropogenic alterations of fluvial systems on viruses require attention. The identification of these considerable knowledge gaps should foster future research efforts.
Collapse
Affiliation(s)
- Peter Peduzzi
- Department of Limnology & Bio-Oceanography, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria.
| |
Collapse
|
37
|
Kim J, Kim CH, Youn SH, Choi TJ. Isolation and Physiological Characterization of a Novel Algicidal Virus Infecting the Marine Diatom Skeletonema costatum. THE PLANT PATHOLOGY JOURNAL 2015; 31:186-191. [PMID: 26060438 PMCID: PMC4454000 DOI: 10.5423/ppj.nt.03.2015.0029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Revised: 03/28/2015] [Accepted: 04/07/2015] [Indexed: 06/04/2023]
Abstract
Diatoms are a major component of the biological community, serving as the principal primary producers in the food web and sustaining oxygen levels in aquatic environments. Among marine planktonic diatoms, the cosmopolitan Skeletonema costatum is one of the most abundant and widespread species in the world's oceans. Here, we report the basic characteristics of a new diatom-infecting S. costatum virus (ScosV) isolated from Jaran Bay, Korea, in June 2008. ScosV is a polyhedral virus (45-50 nm in diameter) that propagates in the cytoplasm of host cells and causes lysis of S. costatum cultures. The infectivity of ScosV was determined to be strain- rather than species-specific, similar to other algal viruses. The burst size and latent period were roughly estimated at 90-250 infectious units/cell and <48 h, respectively.
Collapse
Affiliation(s)
- JinJoo Kim
- Fishery and Ocean Information Division, National Fisheries Research & Development Institute, Busan 619-705,
Korea
| | - Chang-Hoon Kim
- Department of Marine Bio-materials and Aquaculture, Pukyong National University, Busan 608-737,
Korea
| | - Seok-Hyun Youn
- Fishery and Ocean Information Division, National Fisheries Research & Development Institute, Busan 619-705,
Korea
| | - Tae-Jin Choi
- Department of Microbiology, Pukyong National University, Busan 608-737,
Korea
| |
Collapse
|
38
|
Kodama Y, Fujishima M. Symbiotic Chlorella variabilis incubated under constant dark conditions for 24 hours loses the ability to avoid digestion by host lysosomal enzymes in digestive vacuoles of host ciliate Paramecium bursaria. FEMS Microbiol Ecol 2014; 90:946-55. [PMID: 25348325 DOI: 10.1111/1574-6941.12448] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 10/07/2014] [Accepted: 10/19/2014] [Indexed: 01/27/2023] Open
Abstract
Endosymbiosis between symbiotic Chlorella and alga-free Paramecium bursaria cells can be induced by mixing them. To establish the endosymbiosis, algae must acquire temporary resistance to the host lysosomal enzymes in the digestive vacuoles (DVs). When symbiotic algae isolated from the alga-bearing paramecia are kept under a constant dark conditions for 24 h before mixing with the alga-free paramecia, almost all algae are digested in the host DVs. To examine the cause of algal acquisition to the host lysosomal enzymes, the isolated algae were kept under a constant light conditions with or without a photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea for 24 h, and were mixed with alga-free paramecia. Unexpectedly, most of the algae were not digested in the DVs irrespective of the presence of the inhibitor. Addition of 1 mM maltose, a main photosynthetic product of the symbiotic algae or of a supernatant of the isolated algae kept for 24 h under a constant light conditions, did not rescue the algal digestion in the DVs. These observations reveal that unknown factors induced by light are a prerequisite for algal resistance to the host lysosomal enzymes.
Collapse
Affiliation(s)
- Yuuki Kodama
- Department of Biological Science, Faculty of Life and Environmental Sciences, Shimane University, Matsue, Japan
| | | |
Collapse
|
39
|
Agarkova I, Hertel B, Zhang X, Lane L, Tchourbanov A, Dunigan DD, Thiel G, Rossmann MG, Van Etten JL. Dynamic attachment of Chlorovirus PBCV-1 to Chlorella variabilis. Virology 2014; 466-467:95-102. [PMID: 25240455 PMCID: PMC4254200 DOI: 10.1016/j.virol.2014.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/29/2014] [Accepted: 07/01/2014] [Indexed: 11/27/2022]
Abstract
Chloroviruses infect their hosts by specifically binding to and degrading the cell wall of their algal hosts at the site of attachment, using an intrinsic digesting enzyme(s). Chlorovirus PBCV-1 stored as a lysate survived longer than virus alone, suggesting virus attachment to cellular debris may be reversible. Ghost cells (algal cells extracted with methanol) were used as a model to study reversibility of PBCV-1 attachment because ghost cells are as susceptible to attachment and wall digestion as are live cells. Reversibility of attachment to ghost cells was examined by releasing attached virions with a cell wall degrading enzyme extract. The majority of the released virions retained infectivity even after re-incubating the released virions with ghost cells two times. Thus the chloroviruses appear to have a dynamic attachment strategy that may be beneficial in indigenous environments where cell wall debris can act as a refuge until appropriate host cells are available.
Collapse
Affiliation(s)
- Irina Agarkova
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583-0722, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, United States
| | - Brigitte Hertel
- Technische Universität Darmstadt, Department of Biology, Plant Membrane Biophysics, 64287 Darmstadt, Germany
| | - Xinzheng Zhang
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032, United States
| | - Les Lane
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583-0722, United States
| | - Alexander Tchourbanov
- Genetics Core, University of Arizona, 246B Biological Science West, 1041 East Lowell St, Tucson, AZ 85721-0499, United States
| | - David D Dunigan
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583-0722, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, United States
| | - Gerhard Thiel
- Technische Universität Darmstadt, Department of Biology, Plant Membrane Biophysics, 64287 Darmstadt, Germany
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032, United States
| | - James L Van Etten
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583-0722, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, United States.
| |
Collapse
|
40
|
Abstract
UNLABELLED Superoxide dismutases (SODs) are metalloproteins that protect organisms from toxic reactive oxygen species by catalyzing the conversion of superoxide anion to hydrogen peroxide and molecular oxygen. Chlorovirus PBCV-1 encodes a 187-amino-acid protein that resembles a Cu-Zn SOD with all of the conserved amino acid residues for binding copper and zinc (named cvSOD). cvSOD has an internal Met that results in a 165-amino-acid protein (named tcvSOD). Both cvSOD and tcvSOD recombinant proteins inhibited nitroblue tetrazolium reduction of superoxide anion generated in a xanthine-xanthine oxidase system in solution. tcvSOD was chosen for further characterization because it was easier to produce. Recombinant tcvSOD also inhibited a riboflavin photochemical reduction system in a polyacrylamide gel assay, which was blocked by the Cu-Zn SOD inhibitor cyanide but not by azide, which inhibits Fe and Mn SODs. A k(cat)/K(m) value for cvSOD was determined by stop-flow spectrophotometry as 1.28 × 10(8) M(-1) s(-1), suggesting that cvSOD-catalyzed O2 (-) dismutation was not a diffusion controlled encounter. The cvsod gene was expressed as a late gene, and cvSOD activity was detected in purified virions. Superoxide accumulated rapidly during virus infection, and circumstantial evidence indicates that cvSOD aids its decomposition to benefit virus replication. Cu-Zn SOD homologs have been described to occur in 3 other families of large DNA viruses, poxviruses, baculoviruses, and mimiviruses, which group as a clade. Interestingly, cvSOD does not group in the same clade as the other virus SODs but instead groups in an expanded clade that includes Cu-Zn SODs from many cellular organisms. IMPORTANCE Virus infection often leads to an increase in toxic reactive oxygen species in the host, which can be detrimental to virus replication. Viruses have developed various ways to overcome this barrier. As reported in this article, the chloroviruses often encode and package a functional Cu-Zn superoxide dismutase in the virion that presumably lowers the concentration of reactive oxygen induced early during virus infection.
Collapse
|
41
|
Kuznetsov YG, Klose T, Rossmann M, McPherson A. Morphogenesis of mimivirus and its viral factories: an atomic force microscopy study of infected cells. J Virol 2013; 87:11200-13. [PMID: 23926353 PMCID: PMC3807284 DOI: 10.1128/jvi.01372-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/01/2013] [Indexed: 11/20/2022] Open
Abstract
Amoebas infected with mimivirus were disrupted at sequential stages of virus production and were visualized by atomic force microscopy. The development of virus factories proceeded over 3 to 4 h postinfection and resulted from the coalescence of 0.5- to 2-μm vesicles, possibly bearing nucleic acid, derived from either the nuclear membrane or the closely associated rough endoplasmic reticulum. Virus factories actively producing virus capsids on their surfaces were imaged, and this allowed the morphogenesis of the capsids to be delineated. The first feature to appear on a virus factory surface when a new capsid is born is the center of a stargate, which is a pentameric protein oligomer. As the arms of the stargate grow from the pentamer, a rough disk the diameter of a capsid thickens around it. This marks the initial emergence of a protein-coated membrane vesicle. The capsid self-assembles on the vesicle. Hillocks capped by different pentameric proteins spontaneously appear on the emerging vesicle at positions that are ultimately occupied by 5-fold icosahedral vertices. A lattice of coat protein nucleates at each of the 5-fold vertices, but not at the stargate, and then spreads outward from the vertices over the surface, merging seamlessly to complete the icosahedral capsid. Filling with DNA and associated proteins occurs by the transfer of nucleic acid from the interior of the virus factory into the nearly completed capsids. The portal, through which the DNA enters, is sealed by a plug of protein having a diameter of about 40 nm. A layer of integument protein that anchors the surface fibers is acquired by the passage of capsids through a membrane enriched in the protein. The coating of surface fibers is similarly acquired when the integument protein-coated capsids pass through a second membrane that has a forest of surface fibers embedded on one side.
Collapse
Affiliation(s)
- Yuri G. Kuznetsov
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California, USA
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Michael Rossmann
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, USA
| | - Alexander McPherson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California, USA
| |
Collapse
|
42
|
Gerken HG, Donohoe B, Knoshaug EP. Enzymatic cell wall degradation of Chlorella vulgaris and other microalgae for biofuels production. PLANTA 2013; 237:239-53. [PMID: 23011569 DOI: 10.1007/s00425-012-1765-0] [Citation(s) in RCA: 228] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 09/04/2012] [Indexed: 05/03/2023]
Abstract
Cell walls of microalgae consist of a polysaccharide and glycoprotein matrix providing the cells with a formidable defense against its environment. We characterized enzymes that can digest the cell wall and weaken this defense for the purpose of protoplasting or lipid extraction. A growth inhibition screen demonstrated that chitinase, lysozyme, pectinase, sulfatase, β-glucuronidase, and laminarinase had the broadest effect across the various Chlorella strains tested and also inhibited Nannochloropsis and Nannochloris strains. Chlorella is typically most sensitive to chitinases and lysozymes, both enzymes that degrade polymers containing N-acetylglucosamine. Using a fluorescent DNA stain, we developed rapid methodology to quantify changes in permeability in response to enzyme digestion and found that treatment with lysozyme in conjunction with other enzymes has a drastic effect on cell permeability. Transmission electron microscopy of enzymatically treated Chlorella vulgaris indicates that lysozyme degrades the outer surface of the cell wall and removes hair-like fibers protruding from the surface, which differs from the activity of chitinase. This action on the outer surface of the cell causes visible protuberances on the cell surface and presumably leads to the increased settling rate when cells are treated with lysozyme. We demonstrate radical ultrastructural changes to the cell wall in response to treatment with various enzyme combinations which, in some cases, causes a greater than twofold increase in the thickness of the cell wall. The enzymes characterized in this study should prove useful in the engineering and extraction of oils from microalgae.
Collapse
Affiliation(s)
- Henri G Gerken
- National Renewable Energy Laboratory, National Bioenergy Center, 15013 Denver West Parkway, Golden, CO 80401, USA
| | | | | |
Collapse
|
43
|
Abstract
In the last twenty years, numerous giant, dsDNA, icosahedral viruses have been discovered and assigned to the nucleocytoplasmic large dsDNA virus (NCLDV) clade. The major capsid proteins of these viruses consist of two consecutive jelly-roll domains, assembled into trimers, with pseudo 6-fold symmetry. The capsomers are assembled into arrays that have either p6 (as in Paramecium bursaria Chlorella virus-1) or p3 symmetry (as in Mimivirus). Most of the NCLDV viruses have a membrane that separates the nucleocapsid from the external capsid.
Collapse
Affiliation(s)
- Chuan Xiao
- Department of Chemistry, University of Texas at El Paso, 79968, USA
| | | |
Collapse
|
44
|
Paramecium bursaria chlorella virus 1 proteome reveals novel architectural and regulatory features of a giant virus. J Virol 2012; 86:8821-34. [PMID: 22696644 DOI: 10.1128/jvi.00907-12] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 331-kbp chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) genome was resequenced and annotated to correct errors in the original 15-year-old sequence; 40 codons was considered the minimum protein size of an open reading frame. PBCV-1 has 416 predicted protein-encoding sequences and 11 tRNAs. A proteome analysis was also conducted on highly purified PBCV-1 virions using two mass spectrometry-based protocols. The mass spectrometry-derived data were compared to PBCV-1 and its host Chlorella variabilis NC64A predicted proteomes. Combined, these analyses revealed 148 unique virus-encoded proteins associated with the virion (about 35% of the coding capacity of the virus) and 1 host protein. Some of these proteins appear to be structural/architectural, whereas others have enzymatic, chromatin modification, and signal transduction functions. Most (106) of the proteins have no known function or homologs in the existing gene databases except as orthologs with proteins of other chloroviruses, phycodnaviruses, and nuclear-cytoplasmic large DNA viruses. The genes encoding these proteins are dispersed throughout the virus genome, and most are transcribed late or early-late in the infection cycle, which is consistent with virion morphogenesis.
Collapse
|
45
|
Van Etten JL, Dunigan DD. Chloroviruses: not your everyday plant virus. TRENDS IN PLANT SCIENCE 2012; 17:1-8. [PMID: 22100667 PMCID: PMC3259250 DOI: 10.1016/j.tplants.2011.10.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/20/2011] [Accepted: 10/25/2011] [Indexed: 05/29/2023]
Abstract
Viruses infecting higher plants are among the smallest viruses known and typically have four to ten protein-encoding genes. By contrast, many viruses that infect algae (classified in the virus family Phycodnaviridae) are among the largest viruses found to date and have up to 600 protein-encoding genes. This brief review focuses on one group of plaque-forming phycodnaviruses that infect unicellular chlorella-like green algae. The prototype chlorovirus PBCV-1 has more than 400 protein-encoding genes and 11 tRNA genes. About 40% of the PBCV-1 encoded proteins resemble proteins of known function including many that are completely unexpected for a virus. In many respects, chlorovirus infection resembles bacterial infection by tailed bacteriophages.
Collapse
Affiliation(s)
- James L Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900, USA.
| | | |
Collapse
|
46
|
MUKHOPADHYAY BANIBRATA, BHATTACHARYYA R. SPATIOTEMPORAL DYNAMICS OF AN ECOEPIDEMIOLOGICAL MODEL WITH STANDARD INCIDENCE. J MECH MED BIOL 2011. [DOI: 10.1142/s0219519407002212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We analyze a mathematical model of predator–prey interaction where the prey population is infected with a viral disease. Infection in the prey population is assumed to follow standard incidence. The dynamical behavior of the system is studied in terms of stability aspects. To model the gestation lag of the predator species and the spatially heterogeneous characteristics of an ecological population, we incorporate the concept of diffusionally coupled delay into the system. The bifurcation behavior of the delayed homogeneous system is studied. The existence of traveling wave solutions for the delay–diffusion model is established. Numerical simulations are performed to justify analytical findings.
Collapse
Affiliation(s)
| | - R. BHATTACHARYYA
- Department of Applied Mathematics, University of Calcutta, Kolkata-700 009, India
| |
Collapse
|
47
|
Meuser JE, Boyd ES, Ananyev G, Karns D, Radakovits R, Narayana Murthy UM, Ghirardi ML, Dismukes GC, Peters JW, Posewitz MC. Evolutionary significance of an algal gene encoding an [FeFe]-hydrogenase with F-domain homology and hydrogenase activity in Chlorella variabilis NC64A. PLANTA 2011; 234:829-43. [PMID: 21643991 DOI: 10.1007/s00425-011-1431-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 05/06/2011] [Indexed: 05/20/2023]
Abstract
[FeFe]-hydrogenases (HYDA) link the production of molecular H(2) to anaerobic metabolism in many green algae. Similar to Chlamydomonas reinhardtii, Chlorella variabilis NC64A (Trebouxiophyceae, Chlorophyta) exhibits [FeFe]-hydrogenase (HYDA) activity during anoxia. In contrast to C. reinhardtii and other chlorophycean algae, which contain hydrogenases with only the HYDA active site (H-cluster), C. variabilis NC64A is the only known green alga containing HYDA genes encoding accessory FeS cluster-binding domains (F-cluster). cDNA sequencing confirmed the presence of F-cluster HYDA1 mRNA transcripts, and identified deviations from the in silico splicing models. We show that HYDA activity in C. variabilis NC64A is coupled to anoxic photosynthetic electron transport (PSII linked, as well as PSII-independent) and dark fermentation. We also show that the in vivo H(2)-photoproduction activity observed is as O(2) sensitive as in C. reinhardtii. The two C. variabilis NC64A HYDA sequences are similar to homologs found in more deeply branching bacteria (Thermotogales), diatoms, and heterotrophic flagellates, suggesting that an F-cluster HYDA is the ancestral enzyme in algae. Phylogenetic analysis indicates that the algal HYDA H-cluster domains are monophyletic, suggesting that they share a common origin, and evolved from a single ancestral F-cluster HYDA. Furthermore, phylogenetic reconstruction indicates that the multiple algal HYDA paralogs are the result of gene duplication events that occurred independently within each algal lineage. Collectively, comparative genomic, physiological, and phylogenetic analyses of the C. variabilis NC64A hydrogenase has provided new insights into the molecular evolution and diversity of algal [FeFe]-hydrogenases.
Collapse
Affiliation(s)
- Jonathan E Meuser
- Division of Environmental Science and Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Zhang X, Xiang Y, Dunigan DD, Klose T, Chipman PR, Van Etten JL, Rossmann MG. Three-dimensional structure and function of the Paramecium bursaria chlorella virus capsid. Proc Natl Acad Sci U S A 2011; 108:14837-42. [PMID: 21873222 PMCID: PMC3169150 DOI: 10.1073/pnas.1107847108] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A cryoelectron microscopy 8.5 Å resolution map of the 1,900 Å diameter, icosahedral, internally enveloped Paramecium bursaria chlorella virus was used to interpret structures of the virus at initial stages of cell infection. A fivefold averaged map demonstrated that two minor capsid proteins involved in stabilizing the capsid are missing in the vicinity of the unique vertex. Reconstruction of the virus in the presence of host chlorella cell walls established that the spike at the unique vertex initiates binding to the cell wall, which results in the enveloped nucleocapsid moving closer to the cell. This process is concurrent with the release of the internal viral membrane that was linked to the capsid by many copies of a viral membrane protein in the mature infectous virus. Simultaneously, part of the trisymmetrons around the unique vertex disassemble, probably in part because two minor capsid proteins are absent, causing Paramecium bursaria chlorella virus and the cellular contents to merge, possibly as a result of enzyme(s) within the spike assembly. This may be one of only a few recordings of successive stages of a virus while infecting a eukaryotic host in pseudoatomic detail in three dimensions.
Collapse
Affiliation(s)
- Xinzheng Zhang
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032; and
| | - Ye Xiang
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032; and
| | - David D. Dunigan
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032; and
| | - Paul R. Chipman
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032; and
| | - James L. Van Etten
- Department of Plant Pathology and Nebraska Center for Virology, University of Nebraska, Lincoln, NE 68583-0900
| | - Michael G. Rossmann
- Department of Biological Sciences, Purdue University, 240 South Martin Jischke Drive, West Lafayette, IN 47907-2032; and
| |
Collapse
|
49
|
Martínez Martínez J, Poulton NJ, Stepanauskas R, Sieracki ME, Wilson WH. Targeted sorting of single virus-infected cells of the coccolithophore Emiliania huxleyi. PLoS One 2011; 6:e22520. [PMID: 21818332 PMCID: PMC3144233 DOI: 10.1371/journal.pone.0022520] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 06/27/2011] [Indexed: 11/19/2022] Open
Abstract
Discriminating infected from healthy cells is the first step to understanding the mechanisms and ecological implications of viral infection. We have developed a method for detecting, sorting, and performing molecular analysis of individual, infected cells of the important microalga Emiliania huxleyi, based on known physiological responses to viral infection. Of three fluorescent dyes tested, FM 1-43 (for detecting membrane blebbing) gave the most unequivocal and earliest separation of cells. Furthermore, we were able to amplify the genomes of single infected cells using Multiple Displacement Amplification. This novel method to reliably discriminate infected from healthy cells in cultures will allow researchers to answer numerous questions regarding the mechanisms and implications of viral infection of E. huxleyi. The method may be transferable to other virus-host systems.
Collapse
Affiliation(s)
| | - Nicole J. Poulton
- Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, United States of America
| | - Ramunas Stepanauskas
- Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, United States of America
| | - Michael E. Sieracki
- Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, United States of America
| | - William H. Wilson
- Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, United States of America
| |
Collapse
|
50
|
Yau S, Lauro FM, DeMaere MZ, Brown MV, Thomas T, Raftery MJ, Andrews-Pfannkoch C, Lewis M, Hoffman JM, Gibson JA, Cavicchioli R. Virophage control of antarctic algal host-virus dynamics. Proc Natl Acad Sci U S A 2011; 108:6163-8. [PMID: 21444812 PMCID: PMC3076838 DOI: 10.1073/pnas.1018221108] [Citation(s) in RCA: 200] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Viruses are abundant ubiquitous members of microbial communities and in the marine environment affect population structure and nutrient cycling by infecting and lysing primary producers. Antarctic lakes are microbially dominated ecosystems supporting truncated food webs in which viruses exert a major influence on the microbial loop. Here we report the discovery of a virophage (relative of the recently described Sputnik virophage) that preys on phycodnaviruses that infect prasinophytes (phototrophic algae). By performing metaproteogenomic analysis on samples from Organic Lake, a hypersaline meromictic lake in Antarctica, complete virophage and near-complete phycodnavirus genomes were obtained. By introducing the virophage as an additional predator of a predator-prey dynamic model we determined that the virophage stimulates secondary production through the microbial loop by reducing overall mortality of the host and increasing the frequency of blooms during polar summer light periods. Virophages remained abundant in the lake 2 y later and were represented by populations with a high level of major capsid protein sequence variation (25-100% identity). Virophage signatures were also found in neighboring Ace Lake (in abundance) and in two tropical lakes (hypersaline and fresh), an estuary, and an ocean upwelling site. These findings indicate that virophages regulate host-virus interactions, influence overall carbon flux in Organic Lake, and play previously unrecognized roles in diverse aquatic ecosystems.
Collapse
Affiliation(s)
- Sheree Yau
- School of Biotechnology and Biomolecular Sciences
| | | | | | | | - Torsten Thomas
- School of Biotechnology and Biomolecular Sciences
- Centre for Marine Bio-Innovation, and
| | - Mark J. Raftery
- Bioanalytical Mass Spectrometry Facility, University of New South Wales, Sydney, New South Wales 2052, Australia
| | | | | | | | - John A. Gibson
- Marine Research Laboratories, Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Hobart, Tasmania 7001, Australia
| | | |
Collapse
|