Should we fear the awakening giant virus? – FranceTV info

By Writing Allodocteurs.fr

Updated 08/09/2015 | 3:20 p.m. published on 08/09/2015 | 3:20 p.m.

The giant viruses, which have a diameter greater than 0.5 micron (0.5 thousandth of a millimeter) are easily visible with a simple optical microscope , unlike the other virus. It can easily be confused with bacteria.

Mollivirus is the fourth family of giant viruses identified since 2003, and the third to be discovered in the permafrost. This discovery demonstrates that giant viruses “are not uncommon and are very diversified,” said AFP Jean-Michel Claverie, one of the coordinators of the study.

Genome intact

The analysis of the DNA contained in the permafrost sample confirmed the presence of the intact genome Mollivirus although at an extremely low concentration.

Mollivirus sibericum has more than 500 genes. It appears as an oblong shell from 0.6 microns long. To multiply, it needs of the host cell nucleus (which is not the case already identified other giant viruses, which simply the cytoplasm of the cell).

“Some particles infectious viral still may be sufficient, in the presence of susceptible host, the resurgence of potentially pathogenic viruses in Arctic regions increasingly coveted for their mineral and oil resources and whose accessibility and industrial exploitation are facilitated by climate change, “notes the CNRS in a statement.

Virus asleep

Global warming frees indeed increasingly polar sea ice, which provides access to Eastern Siberia and Northern by sea routes that did not exist.

“If we are not careful and that these industrialized areas without taking precautions we run the risk of viruses wake up one day such as smallpox once thought eradicated, “notes Mr. Claverie.

Because it is not very difficult to revive these viruses. Having established the absence of pathogenicity Mollivirus sibericum to the mouse and man, this “awakening” has been achieved in the laboratory, using amoebae (single-celled organism) as the host cells . Last year, the team of researchers who signs the study had already managed to revive another type of giant viruses kept in the same sample of permafrost and named Pithovirus .

Source: In-depth study of Mollivirus sibericum, a new 30,000-y old giant virus infecting Acanthamoeba M. Legendre et al.. PNAS , Sept. 7, 2015.

The scientific world, which has long been thought that viruses were necessarily very small and composed only of a handful of genes, discovered in 2003 a surprise first giant viruses, rich of a thousand genes and called Mimivirus (family Megavirus). Another family of giant viruses, pandoravirus , with 2,500 genes, was described in the journal Science in 2013.

Scanning electron microscopy of the particles of the 4 families now known giant viruses. The larger dimensions are approximately 0.6 micron (Mollivirus) 1.5 micron (pandoravirus) – IGS © CNRS / AMU

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