Virophages of Giant Viruses: An Update at Eleven

The last decade has been marked by two eminent discoveries that have changed our perception of the virology field: The discovery of giant viruses and a distinct new class of viral agents that parasitize their viral factories, the virophages. Coculture and metagenomics have actively contributed to the expansion of the virophage family by isolating dozens of new members. This increase in the body of data on virophage not only revealed the diversity of the virophage group, but also the relevant ecological impact of these small viruses and their potential role in the dynamics of the microbial network. In addition, the isolation of virophages has led us to discover previously unknown features displayed by their host viruses and cells. In this review, we present an update of all the knowledge on the isolation, biology, genomics, and morphological features of the virophages, a decade after the discovery of their first member, the Sputnik virophage. We discuss their parasitic lifestyle as bona fide viruses of the giant virus factories, genetic parasites of their genomes, and then their role as a key component or target for some host defense mechanisms during the tripartite virophage–giant virus–host cell interaction. We also present the latest advances regarding their origin, classification, and definition that have been widely discussed.

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First evidence of host range expansion in virophages and its potential impact on giant viruses and host cells

10.1101/780841 ◽

2019 ◽

Author(s):

Said Mougari ◽

Nisrine Chelkha ◽

Dehia Sahmi-Bounsiar ◽

Fabrizio Di Pinto ◽

Philippe Colson ◽

...

Keyword(s):

Host Range ◽

Range Expansion ◽

Virus Production ◽

Host Cells ◽

Giant Virus ◽

Dna Viruses ◽

Host Range Expansion ◽

Parasitic Lifestyle ◽

Giant Viruses ◽

Viral Host Range

AbstractVirophages are satellite-like double stranded DNA viruses whose replication requires the presence of two biological entities, a giant virus and a protist. In this report, we present the first evidence of host range expansion in a virophage. We demonstrated that the Guarani virophage was able to spontaneously expand its viral host range to replicate with two novel giant viruses that were previously nonpermissive to this virophage. We were able to characterize a potential genetic determinant of this cross-species infection. We then highlighted the relevant impact of this host adaptation on giant viruses and protists by demonstrating that coinfection with the mutant virophage abolishes giant virus production and rescues the host cell population from lysis. The results of our study help to elucidate the parasitic lifestyle of virophages and their interactions with giant viruses and protists.

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The Basics of Microbiology

10.33442/vt202101 ◽

2021 ◽

Author(s):

Werner Solbach

Keyword(s):

Infectious Diseases ◽

Defense Mechanisms ◽

Wide Spectrum ◽

Severe Disease ◽

Laboratory Diagnosis ◽

Asymptomatic Infection ◽

The Body ◽

Sufficient Evidence ◽

Effective Measure ◽

Hygiene Measures

Microorganisms constitute 70 percent of the biomass on Planet Earth. Comparatively few species are adapted to colonize human surfaces and form a complex Meta-Organism with manyfold mutual benefits. Occasionally, microorganisms may overcome the barriers of the skin and mucosal surfaces and may multiply locally or in multiple sites inside the body. This process is called infection. Infections can be caused by bacteria, viruses, parasites, helminths, and fungi. Immediately after infection, numerous defense mechanisms of the immune system are activated to combat replication of the microbes. There is a balance between microorganism and human defense mechanisms, which may lead to either asymptomatic infection or result in a wide spectrum of symptoms from mild to severe disease and even death. The most important factors in the diagnosis of infectious diseases are a careful history, physical examination and the appropriate collection of body fluids and tissues. Laboratory diagnosis requires between 2 and 72 hours. Wherever possible, antibiotics should only be used when sufficient evidence of efficacy is available. Then, however, they should be used as early as possible and in high doses. In addition to everyday hygiene measures, vaccination is the most effective measure to prevent infectious diseases.

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Encapsulation and Ultrasound-Triggered Release of G-Quadruplex DNA in Multilayer Hydrogel Microcapsules

Polymers ◽

10.3390/polym10121342 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1342 ◽

Cited By ~ 4

Author(s):

Aaron Alford ◽

Brenna Tucker ◽

Veronika Kozlovskaya ◽

Jun Chen ◽

Nirzari Gupta ◽

...

Keyword(s):

Nucleic Acids ◽

Defense Mechanisms ◽

The Body ◽

Stimuli Responsive ◽

Triggered Release ◽

Quadruplex Dna ◽

Nucleic Acid Therapeutics ◽

Wide Range ◽

G Quadruplex ◽

Hydrogel Capsules

Nucleic acid therapeutics have the potential to be the most effective disease treatment strategy due to their intrinsic precision and selectivity for coding highly specific biological processes. However, freely administered nucleic acids of any type are quickly destroyed or rendered inert by a host of defense mechanisms in the body. In this work, we address the challenge of using nucleic acids as drugs by preparing stimuli responsive poly(methacrylic acid)/poly(N-vinylpyrrolidone) (PMAA/PVPON)n multilayer hydrogel capsules loaded with ~7 kDa G-quadruplex DNA. The capsules are shown to release their DNA cargo on demand in response to both enzymatic and ultrasound (US)-triggered degradation. The unique structure adopted by the G-quadruplex is essential to its biological function and we show that the controlled release from the microcapsules preserves the basket conformation of the oligonucleotide used in our studies. We also show that the (PMAA/PVPON) multilayer hydrogel capsules can encapsulate and release ~450 kDa double stranded DNA. The encapsulation and release approaches for both oligonucleotides in multilayer hydrogel microcapsules developed here can be applied to create methodologies for new therapeutic strategies involving the controlled delivery of sensitive biomolecules. Our study provides a promising methodology for the design of effective carriers for DNA vaccines and medicines for a wide range of immunotherapies, cancer therapy and/or tissue regeneration therapies in the future.

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Giant Viruses and the Tree of Life

Inference: International Review of Science ◽

10.37282/991819.21.43 ◽

2021 ◽

Vol 6 (2) ◽

Author(s):

Patrick Forterre

Keyword(s):

Tree Of Life ◽

Current Understanding ◽

Giant Virus ◽

Giant Viruses

When the first giant virus, the mimivirus, was discovered in 1992, it was misidentified as a bacterium because it was too large to have been a virus by the current understanding. Ever since, biologists have been debating how viruses should be categorized and described. Are they living? Are they something else? What is their place on the tree of life?

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Advantages and limits of metagenomic assembly and binning of a giant virus

10.1101/2020.01.10.902254 ◽

2020 ◽

Cited By ~ 1

Author(s):

Frederik Schulz ◽

Julien Andreani ◽

Rania Francis ◽

Jacques Yaacoub Bou Khalil ◽

Janey Lee ◽

...

Keyword(s):

Size Range ◽

Sequence Data ◽

Giant Virus ◽

Sample Matrix ◽

Environmental Sequence ◽

Successful Recovery ◽

Metagenome Assembly ◽

Giant Viruses ◽

Metagenomic Assembly ◽

Virus Genomes

AbstractGiant viruses have large genomes, often within the size range of cellular organisms. This distinguishes them from most other viruses and demands additional effort for the successful recovery of their genomes from environmental sequence data. Here we tested the performance of genome-resolved metagenomics on a recently isolated giant virus, Fadolivirus, by spiking it into an environmental sample from which two other giant viruses were isolated. At high spike-in levels, metagenome assembly and binning led to the successful genomic recovery of Fadolivirus from the sample. A complementary survey of viral hallmark genes indicated the presence of other giant viruses in the sample matrix, but did not detect the two isolated from this sample. Our results indicate that genome-resolved metagenomics is a valid approach for the recovery of near-complete giant virus genomes given that sufficient clonal particles are present. Our data also underline that a vast majority of giant viruses remain currently undetected, even in an era of terabase-scale metagenomics.

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Boiling Acid Mimics Intracellular Giant Virus Genome Release

10.1101/777854 ◽

2019 ◽

Author(s):

Jason R. Schrad ◽

Jônatas S. Abrahão ◽

Juliana R. Cortines ◽

Kristin N. Parent

Keyword(s):

Mass Spectrometry ◽

Virus Infection ◽

Virus Genome ◽

Life Cycles ◽

Giant Virus ◽

Infection Mechanisms ◽

Specific Proteins ◽

Giant Viruses ◽

Molecular Forces

SummarySince their discovery, giant viruses have expanded our understanding of the principles of virology. Due to their gargantuan size and complexity, little is known about the life cycles of these viruses. To answer outstanding questions regarding giant virus infection mechanisms, we set out to determine biomolecular conditions that promote giant virus genome release. We generated four metastable infection intermediates in Samba virus (lineage A Mimiviridae) as visualized by cryo-EM, cryo-ET, and SEM. Each of these four intermediates reflects a stage that occurs in vivo. We show that these genome release stages are conserved in other, diverse giant viruses. Finally, we identified proteins that are released from Samba and newly discovered Tupanvirus through differential mass spectrometry. Our work revealed the molecular forces that trigger infection are conserved amongst disparate giant viruses. This study is also the first to identify specific proteins released during the initial stages of giant virus infection.

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Lipid role in the immune system

INFORM International News on Fats Oils and Related Materials ◽

10.21748/inform.11.2021.06 ◽

2021 ◽

Vol 32 (10) ◽

pp. 6-10

Author(s):

Rebecca Guenard ◽

Keyword(s):

Fatty Acids ◽

Immune System ◽

Essential Fatty Acids ◽

The Body ◽

New Members ◽

Inflammatory Pathways ◽

Anti Inflammatory

The essential fatty acids react with enzymes to produce a group of compounds known as specialized pro-resolving mediators, or SPMs. Researchers continually discover new members of the four groups of precursors that comprise the SPM family, called lipoxins, resolvins, protectins, and maresins. These stereospecific molecules shut down inflammation and restore the body to homeostasis, a mechanism researchers are targeting for treatment as an alternative to anti-inflammatory pathways.

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Giant virus vs amoeba: fight for supremacy

Virology Journal ◽

10.1186/s12985-019-1244-3 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 1

Author(s):

Graziele Oliveira ◽

Bernard La Scola ◽

Jônatas Abrahão

Keyword(s):

Giant Virus ◽

Host Pathogen Interactions ◽

Free Living ◽

Host Interactions ◽

Virus Particles ◽

Recent Advances ◽

Host Pathogen ◽

New Hosts ◽

Giant Viruses

Abstract Since the discovery of mimivirus, numerous giant viruses associated with free-living amoebae have been described. The genome of giant viruses can be more than 2.5 megabases, and virus particles can exceed the size of many bacteria. The unexpected characteristics of these viruses have made them intriguing research targets and, as a result, studies focusing on their interactions with their amoeba host have gained increased attention. Studies have shown that giant viruses can establish host–pathogen interactions, which have not been previously demonstrated, including the unprecedented interaction with a new group of small viruses, called virophages, that parasitize their viral factories. In this brief review, we present recent advances in virophage–giant virus–host interactions and highlight selected studies involving interactions between giant viruses and amoebae. These unprecedented interactions involve the giant viruses mimivirus, marseillevirus, tupanviruses and faustovirus, all of which modulate the amoeba environment, affecting both their replication and their spread to new hosts.

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Host–virus interactions and defense mechanisms for giant viruses

Annals of the New York Academy of Sciences ◽

10.1111/nyas.14469 ◽

2020 ◽

Author(s):

Nisrine Chelkha ◽

Anthony Levasseur ◽

Bernard La Scola ◽

Philippe Colson

Keyword(s):

Defense Mechanisms ◽

Giant Viruses ◽

Host Virus Interactions ◽

Virus Interactions

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OOCHIP: Compartmentalized Microfluidic Perfusion System with Porous Barriers for Enhanced Cell–Cell Crosstalk in Organ-on-a-Chip

Micromachines ◽

10.3390/mi11060565 ◽

2020 ◽

Vol 11 (6) ◽

pp. 565

Author(s):

Qasem Ramadan ◽

Sajay Bhuvanendran Nair Gourikutty ◽

Qingxin Zhang

Keyword(s):

Drug Efficacy ◽

Human Adipose Tissue ◽

Cell Types ◽

Cell Interaction ◽

The Body ◽

Close Proximity ◽

Porous Barriers ◽

Cell Cell

Improved in vitro models of human organs for predicting drug efficacy, interactions, and disease modelling are crucially needed to minimize the use of animal models, which inevitably display significant differences from the human disease state and metabolism. Inside the body, cells are organized either in direct contact or in close proximity to other cell types in a tightly controlled architecture that regulates tissue function. To emulate this cellular interface in vitro, an advanced cell culture system is required. In this paper, we describe a set of compartmentalized silicon-based microfluidic chips that enable co-culturing several types of cells in close proximity with enhanced cell–cell interaction. In vivo-like fluid flow into and/or from each compartment, as well as between adjacent compartments, is maintained by micro-engineered porous barriers. This porous structure provides a tool for mimicking the paracrine exchange between cells in the human body. As a demonstrating example, the microfluidic system was tested by culturing human adipose tissue that is infiltrated with immune cells to study the role if the interplay between the two cells in the context of type 2 diabetes. However, the system provides a platform technology for mimicking the structure and function of single- and multi-organ models, which could significantly narrow the gap between in vivo and in vitro conditions.

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