Ancient pathogens reanimated: “zombie viruses” in the permafrost are still contagious

Ancient pathogens reanimated
“Zombie viruses” in the permafrost are still contagious

Plants, worms, even whole prehistoric rhinos or mammoths: huge amounts of biomass are bound in the permafrost of the Arctic – including viruses. Now, when the ice thaws, they are released and can infect even after tens of thousands of years.

Climate change is progressing, the earth is warming up. This is already having an impact on the northern hemisphere. Large parts of the permafrost are slowly but surely melting there. This not only releases problematic amounts of CO2 and methane, but also thaws frozen creatures. While finds of long-extinct animal species are hailed as spectacular, they can also have far-reaching implications. That’s how it worked a research team led by Jean-Marie Alempic from the Aix-Marseille University in France to detect 13 previously unknown virus types from corresponding samples – and to activate them again.

The youngest pathogen was 27,000 years old, while the oldest virus was locked in the ice for a full 48,500 years. The latter is a giant amoeba-infecting virus called Pandoravirus yedoma, which originated in a lake in Yakutia, Russia. Giant viruses are significantly larger than average bacteria. The Pandoravirus yedoma is so large that it can already be detected with a normal light microscope. These viruses, which specialize in protozoa, are harmless to humans.

The research team also revived three other viruses from a 27,000-year-old sample of frozen mammoth feces and a patch of permafrost filled with a large amount of mammoth wool. Two viruses have been isolated from the frozen stomach contents of a Siberian wolf.

In fact, the scientists reanimated other frozen viruses, but these seven are special because they differed from all currently known viruses. This should ensure that it is not a matter of contamination with contemporary virus material.

Lauterbach: First climate change, then zoonosis, then pandemic

The success in awakening suggests that many other viruses conserved in permafrost can also be resurrected. In their preprint study, the research team criticized the fact that resurrected viruses had only been reported in two studies from 2014 and 2015. This suggests that this is a rare phenomenon. However, the results that have now been published suggest that it can occur much more frequently. And: The assumption that “‘zombie viruses’ do not pose a threat to public health” is also wrong, according to the study.

Alempic and his team estimate that there may still be thousands of unknown viruses in the permafrost, some of which could potentially infect humans. In view of the increasing use of the permafrost areas and climate change, which is causing the soil to thaw more, there are certain risks here, the researchers write.

Federal Health Minister Karl Lauterbach also refers to the dangers of the melting ice on the poles on Twitter. “In the thawed carcasses there are viruses that are more than 10,000 years old. This is also an example of how we use the chain first climate change, then zoonosis, then outbreak, then pandemic,” commented the SPD politician and epidemiologist on the study France, which has yet to be examined by experts.

In recent years, evidence has accumulated that the permafrost is a gigantic reservoir of ancient viruses and microbes that are activated and released again as the environment changes. Several times in the past, it has been possible to bring viruses that are thousands of years old back to life – although, strictly speaking, viruses are not considered “life” because they need a host to reproduce. According to the scientists, the dangers emanating from such “zombie viruses” need to be examined more closely.

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