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16 pages, 2309 KiB

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An Update on Eukaryotic Viruses Revived from Ancient Permafrost

by Jean-Marie Alempic, Audrey Lartigue, Artemiy E. Goncharov, Guido Grosse, Jens Strauss, Alexey N. Tikhonov, Alexander N. Fedorov, Olivier Poirot, Matthieu Legendre, Sébastien Santini, Chantal Abergel and Jean-Michel Claverie

Viruses 2023, 15(2), 564; https://doi.org/10.3390/v15020564 - 18 Feb 2023

Cited by 37 | Viewed by 56422

Abstract

One quarter of the Northern hemisphere is underlain by permanently frozen ground, referred to as permafrost. Due to climate warming, irreversibly thawing permafrost is releasing organic matter frozen for up to a million years, most of which decomposes into carbon dioxide and methane, further enhancing the greenhouse effect. Part of this organic matter also consists of revived cellular microbes (prokaryotes, unicellular eukaryotes) as well as viruses that have remained dormant since prehistorical times. While the literature abounds on descriptions of the rich and diverse prokaryotic microbiomes found in permafrost, no additional report about “live” viruses have been published since the two original studies describing pithovirus (in 2014) and mollivirus (in 2015). This wrongly suggests that such occurrences are rare and that “zombie viruses” are not a public health threat. To restore an appreciation closer to reality, we report the preliminary characterizations of 13 new viruses isolated from seven different ancient Siberian permafrost samples, one from the Lena river and one from Kamchatka cryosol. As expected from the host specificity imposed by our protocol, these viruses belong to five different clades infecting Acanthamoeba spp. but not previously revived from permafrost: Pandoravirus, Cedratvirus, Megavirus, and Pacmanvirus, in addition to a new Pithovirus strain. Full article

(This article belongs to the Special Issue Research Progresses of Giant Viruses: A Themed Issue Dedicated to Professor Jean-Michel Claverie)

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10 pages, 7364 KiB

Open AccessArticle

Diversity of Amoeba-Associated Giant Viruses Isolated in Algeria

by Hadjer Boudjemaa, Julien Andreani, Idir Bitam and Bernard La Scola

Diversity 2020, 12(6), 215; https://doi.org/10.3390/d12060215 - 29 May 2020

Cited by 6 | Viewed by 3843

Abstract

The discovery of several giant amoeba viruses has opened up a novel area in the field of virology. Despite this, knowledge about ecology of these viruses remains patchy. In this study, we aimed to characterize the diversity of giant viruses in Algeria by inoculating 64 environmental samples on various amoeba strains. After isolation by co-culture with nine amoeba supports, flow cytometry and electron microscopy were used to putatively identify viruses. Definitive identification was performed by PCR and sequencing. Mimiviruses, marseilleviruses, faustoviruses and cedratviruses were the main viruses isolated in this study. Moreover, a new virus, which we named fadolivirus, was also isolated and was found to belong to the recent metagenomic descriptions of Klosneuvirinae. Despite the use of 9 amoeba supports for co-culture, most of the isolates were obtained from two amoebas: Acanthamoeba castellanii Neff and Vermamoeba vermiformis CDC 19. Finally, the viruses most frequently isolated were marseilleviruses (55.5%) and Mimiviruses (22.2%). This work shows that the isolation of viruses previously detected by metagenomic analyses can be tedious, but possible. Full article

(This article belongs to the Special Issue Giant Virus Biology and Biodiversity)

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11 pages, 4572 KiB

Open AccessArticle

Cedratvirus, a Double-Cork Structured Giant Virus, is a Distant Relative of Pithoviruses

by Julien Andreani, Sarah Aherfi, Jacques Yaacoub Bou Khalil, Fabrizio Di Pinto, Idir Bitam, Didier Raoult, Philippe Colson and Bernard La Scola

Viruses 2016, 8(11), 300; https://doi.org/10.3390/v8110300 - 3 Nov 2016

Cited by 82 | Viewed by 10815

Abstract

Most viruses are known for the ability to cause symptomatic diseases in humans and other animals. The discovery of Acanthamoeba polyphaga mimivirus and other giant amoebal viruses revealed a considerable and previously unknown area of uncharacterized viral particles. Giant viruses have been isolated from various environmental samples collected from very distant geographic places, revealing a ubiquitous distribution. Their morphological and genomic features are fundamental elements for classifying them. Herein, we report the isolation and draft genome of Cedratvirus, a new amoebal giant virus isolated in Acanthamoeba castellanii, from an Algerian environmental sample. The viral particles are ovoid-shaped, resembling Pithovirus sibericum, but differing notably in the presence of two corks at each extremity of the virion. The draft genome of Cedratvirus—589,068 base pairs in length—is a close relative of the two previously described pithoviruses, sharing 104 and 113 genes with P. sibericum and Pithovirus massiliensis genomes, respectively. Interestingly, analysis of these viruses’ core genome reveals that only 21% of Cedratvirus genes are involved in best reciprocal hits with the two pithoviruses. Phylogeny reconstructions and comparative genomics indicate that Cedratvirus is most closely related to pithoviruses, and questions their membership in an enlarged putative Pithoviridae family. Full article

(This article belongs to the Special Issue Viruses of Protozoa)

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