A Need to Discover the World of Giant Viruses

Raoult, Didier

doi:10.1159/000355317

Cited by 2 publications

(2 citation statements)

References 26 publications

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“…It could be considered as the first virus infecting another virus, after the successive discoveries since the 1890s of viruses of eukaryotes, bacteria, and archaea. The discovery of the virophage amplified the revolution initiated by giant viruses in virology [19] and raised considerable interest in the field of evolutionary biology [2,4,20,21,22]. …”

Section: Introductionmentioning

confidence: 99%

The Expanding Family of Virophages

Bekliz

Colson

Scola

2016

Viruses

118

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Virophages replicate with giant viruses in the same eukaryotic cells. They are a major component of the specific mobilome of mimiviruses. Since their discovery in 2008, five other representatives have been isolated, 18 new genomes have been described, two of which being nearly completely sequenced, and they have been classified in a new viral family, Lavidaviridae. Virophages are small viruses with approximately 35–74 nm large icosahedral capsids and 17–29 kbp large double-stranded DNA genomes with 16–34 genes, among which a very small set is shared with giant viruses. Virophages have been isolated or detected in various locations and in a broad range of habitats worldwide, including the deep ocean and inland. Humans, therefore, could be commonly exposed to virophages, although currently limited evidence exists of their presence in humans based on serology and metagenomics. The distribution of virophages, the consequences of their infection and the interactions with their giant viral hosts within eukaryotic cells deserve further research.

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Section: Introductionmentioning

confidence: 99%

The Expanding Family of Virophages

Bekliz

Colson

Scola

2016

Viruses

118

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“…However, these filters also often exclude large microbes. The recent discovery of Mimiviruses infecting amoeba highlighted how ad example the use of a 0.45 μm filter may prevent the recovery of giant viruses 9 . Therefore, we adopted some of the strategies currently in use for the isolation of amoeba giant viruses, but the harvest of human giant microbes from cancer specimens did not require amoeba co-cultures.…”

Section: Introductionmentioning

confidence: 99%

Discovery of the First Human Retro-Giant Virus: Description of its morphology, retroviral kinase and ability to induce tumours in mice

Lusi

Caicci

2019

Preprint

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BackgroundThe study of retroviruses dates back to the early 1900s during investigations on neoplastic diseases in chickens. Subsequently, Robert Gallo reported the first human retrovirus HLTV in 1980. What we report here is not an archetypal retrovirus, but the discovery of an oncogenic giant microbial agent with a mega-genome, where the transforming retroviral nature co-exists with multiple archaeal oncogenes.MethodsAfter their isolation from human T cells Leukaemia, these organisms were examined at electron microscopy, tested for reverse transcriptase activity, fully sequenced, used for transformation tests on NIH-3T3 cells in vitro and tumours formation in mice. Same type of particles were also isolated from Canine Transmissible Venereal Tumour (CTVT), the oldest contagious cancer in nature.ResultsEM showed the presence of giant viral particles displaying retroviral antigens. These microbial entities harbour in their mega-genome a transforming retroviral kinase, cell-based oncogenes and have reverse transcriptase activity. The purified viral particles transformed NIH-3T3 cells and induced metastatic tumours in nude mice, three weeks post infection. Ruling out the possible presence of filterable retroviruses, a filtered supernatant did not display RT activity and did not transforms.ConclusionsWe discovered an ancestral microbial agent, acutely transforming. For its giant dimensions, the ability to retain the Gram stain, the presence of a mega-genome and its retroviral nature, we tentatively named the agent Retro-Giant-Virus (RGV). However, distinct from amoeba giant Mimiviruses, this transforming human agent has a different nature and does not require for its isolation amoeba co-culture, since amoeba is not its natural host.The morphology, biology and genetic features allocate this mammalian giant microbe halfway in between a classic oncogenic virus and an infectious cancer cell. Its transforming nature goes with its constant ability to induce tumours formation in mice.

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A Need to Discover the World of Giant Viruses

Cited by 2 publications

References 26 publications

The Expanding Family of Virophages

The Expanding Family of Virophages

Discovery of the First Human Retro-Giant Virus: Description of its morphology, retroviral kinase and ability to induce tumours in mice

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