Scientists at the University of Marseille, in France, thawed and revived 13 viruses of up to 48,000 years that were dormant in the permafrost – permanently frozen soil – of Siberia. Although it seems risky, the researchers emphasize that the objective is to understand how the melting of the region can lead to the spread of new pathogens that cause health emergencies, such as a pandemic.
In the study, available on the BioRxiv pre-print platform, not yet peer-reviewed, those responsible write that “due to climate warming, irreversible permafrost thaw is releasing frozen organic matter for up to a million years”, and that part of this matter consists of “viruses that have lain dormant since prehistoric times”.
This is not the first study of its kind, but it is the most extensive and has unfrozen older viruses so far. The 13 pathogens belong to five different classes, some proposed in an unprecedented way by the work. They were collected from 7 samples from several different parts of the permafrost. Some of them came from frozen mammoth droppings, others from the stomachs of Siberian wolves.
Then, the scientists introduced the viruses, in the laboratory, into a culture of amoebas of the Acanthamoeba spp species, where they were able to infect the cells and replicate. The experiment, according to the researchers, confirms the ability of these pathogens to “remain infectious after more than 48,500 years spent in deep permafrost.”
“We believe that our results with viruses that infect Acanthamoeba can be extrapolated to many other DNA viruses capable of infecting humans or animals. Therefore, it is likely that ancient permafrost (eventually well over 50,000 years old) releases these unknown viruses after thawing. (…) The risk tends to increase in the context of global warming, when permafrost melting will continue to accelerate and more people will be populating the Arctic following industrial developments”, write the authors in the study.
Regarding the dangers of the experiment, such as a virus “escape” from the laboratory, they point out that they looked for viruses that infect amoebas precisely because of their evolutionary distance from humans and other mammals. For scientists, this is the “best possible protection against an accidental infection of laboratory workers or the spread of a terrible virus”.
“The biological risk associated with the revival of prehistoric viruses that infect amoebas is therefore entirely negligible,” say the researchers. They point out that there are other studies that look for paleoviruses (ancient pathogens) more likely to infect mammals, but they are conducted in high biosafety centers.
