It may sound like something out of a science fiction movie. Still, it is true: scientists have succeeded in resurrecting ‘zombie viruses’ that have lain dormant beneath the Siberian permafrost for millennia. With some of the pathogens as old as 50,000 years, this marks a new record age for viruses returning to infectious capability.
Lurking under the ice A study conducted by Claverie et. al. isolated thirteen new species of viruses from seven Siberian samples, including frozen ground, mammoth wool and excrement, and the intestines of a frozen Siberian wolf. The oldest, named Pandoravirus yedoma by its discoverers (Pandoraviruses being giant viruses visible under ordinary microscopes and Yedoma the type of soil in which it was discovered), has been lurking beneath the Arctic ice for 48,500 years. All the viral specimens infect amoeba, a type of protozoan- they are small, single-celled animals. Although not a danger to humans, they have proven infectious capacity- researchers introduced the viruses to lab-grown cultures of amoeba; results showed that all thirteen viruses could successfully invade and replicate in host cells.
Growing trend Another study by the same team of scientists previously uncovered not one but two other 30,000-year-old viruses from the same region in 2014. The two specimens christened Mollivirus sibericum and Pithovirus sibericum, both infect amoeba; the two are also pandoraviruses, with Pithovirus being the largest known viral genus. The scientists’ research, then, represents an emerging trend. A similar incident, albeit with far greater consequences, took place in July 2016 in Siberia: after melting permafrost exposed the carcass of a reindeer killed in an anthrax outbreak, the deadly Anthrax spores spread like wildfire among local nomadic communities, hospitalising 100 people (killing a twelve-year-old child) and killing over two thousand reindeer, with much more infected.
Takeaways Permafrost, which refers to permanently frozen ground, covers around 16 million square kilometres, or over 10% of the Earth’s total exposed land surface. However, that amount is shrinking rapidly as global warming wreaks havoc on ice sheets. The effects of thawing permafrost could be potentially devastating: most of Russia, a country home to almost 150 million people, is underlain by permafrost.
As the permafrost melts, it leaves behind water and soil, releasing trapped gases- such as methane and carbon dioxide, which accelerate climate change- and, more ominously, bacteria and viruses that have been entombed in ice for thousands of years. A huge biomass of unknown pathogens is released into the atmosphere in this way every year as more and more ice thaws in the face of climate change. The risks of accidentally reawakening ‘zombie’ microbes are only heightened by the rapid urbanisation of Arctic areas and increased exploration by companies for undiscovered oil and natural gas deposits.
The global health system is already in deplorable condition, with countries’ complacency and unpreparedness being amply demonstrated by the ongoing COVID-19 pandemic. We were completely blindsided by the emergence of a hitherto unknown infection, the consequences being 650 million infections and over 6 million deaths. With the frozen wilds opening up, we risk unleashing thousands of novel pathogens on a fragile healthcare ecosystem. It may only be a matter of time before the next pandemic emerges from the tundra.
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29-Jan-2023 , 12:52 PM
28-Jan-2023 , 05:05 AM