By Chris Skeldon 
Scientists say the fact that viruses that infect amoeba are still infectious after such a long time points to a larger potential problem in humans.
Rising temperatures in the Arctic are thawing the region’s permafrost, a frozen layer of soil underground, and potentially activating viruses that can endanger animal and human health after dormant for tens of thousands of years.
While an epidemic caused by a disease from the distant past sounds like the plot of a science fiction movie, scientists warn against underestimating the risks. Chemical and radioactive waste dating back to the Cold War, which has the potential to harm wildlife and disrupt ecosystems, can also be released during the melt.
“There’s a lot going on with troubling permafrost and it really shows why it’s so important to preserve as much permafrost as possible,” said Kimberly Miner, a climate scientist at NASA’s Jet Propulsion Laboratory at Caltech. in Pasadena, California.
To better understand the risks posed by frozen viruses, Jean-Michel Clavery, professor emeritus of medicine and genomics at Aix-Marseille University School of Medicine in Marseille, France, tested soil samples taken from Siberian permafrost to see if any viral particles were present in them. It’s still contagious.
He’s been looking for what he calls the “zombie virus” – and he’s found quite a few.
Their efforts to detect viruses frozen in permafrost were inspired in part by a team of Russian scientists who, in 2012, reanimated a wildflower from the tissue of a 30,000-year-old seed found in a squirrel burrow. Since then, scientists have also brought ancient microscopic animals back to life.
In 2014, he was able to revive a virus he and his team had isolated from permafrost, making it infectious for the first time in 30,000 years, by introducing it into cultured cells. To be on the safe side, he chose to study a virus that could target only single-celled amoebas, not animals or humans.
These latest strains represent five new viral families, in addition to the two he brought back before. The oldest was about 48,500 years old, based on radiocarbon dating of the soil, and came from a soil sample taken from an underground lake 16 meters below the surface.
He repeated the feat in 2015, isolating a different type of virus that also targeted amoeba. In their latest paper, published February 18 in the Journal of Viruses, Claverie and his team isolated several ancient virus strains from different permafrost samples taken from seven different places in Siberia and showed that each of them could infect cultured amoeba cells.
Clavery said the fact that viruses that infect amoeba remain infectious after such a long time is indicative of a larger problem for humans. He worries that people will see his research as a scientific curiosity and not recognize the potential for ancient viruses to come back to life as a serious threat to public health.
source: CNN Brazil