Heating climate could increase risk of Arctic virus spillover
New study suggests that a warmer Arctic might increase the danger of “viral spillover” by putting viruses in touch with new ecosystems and hosts.
Viruses need hosts such as people, animals, plants, or fungus to reproduce and propagate; nevertheless, viruses may sometimes move to a new host that does not have immunity, as was the case with the COVID-19 pandemic.
Canadian researchers hoped to learn more about the potential effects of climate change on spillover risk by analysing Arctic landscape samples from Lake Hazen.
The Arctic Ocean’s biggest lake is “really unlike any other location I’ve seen,” researcher and current medical student at the University of Toronto, Graham Colby, told the AFP news agency.
Despite it being spring in Canada in May, the research team had to remove snow and dig through two metres of ice to collect samples from the lakebed and the soil that forms a riverbed for melting glacier water in the northern summer.
The silt from the lake was hauled up approximately 300 metres (980 feet) of water using ropes and a snowmobile, and then sequenced for DNA and RNA (the genetic blueprints and messengers of life, respectively).
“This allowed us to identify what viruses exist in a particular environment, and what possible hosts are also there,” said Stephane Aris-Brosou, the study’s lead author and an associate professor in the biology department at the University of Ottawa.
But the scientists needed to look at the evolutionary history of each virus and host to determine the likelihood that they would switch hosts.
“Basically what we wanted to do is assess how similar these trees are,” said Audree Lemieux, the study’s lead author.
Genetic similarity between a virus and its host indicates coevolution, whereas genetic divergence indicates spillover.
A virus that has already infected many hosts is more likely to do so again.
According to Aris-Brosou, “which is directly associated to the danger of spillover,” the study revealed striking disparities between viruses and hosts in the lakebed.
The researchers hypothesise that this is because water erodes the topsoil, destroying organisms and restricting contacts between viruses and possible new hosts, making the difference less pronounced in riverbeds.
Instead, they’ve been washing into the lake, which has seen “dramatic alteration” in recent years due to the increased sedimentation brought in by water from melting glaciers, as the report notes.
Lemieux predicted that this would result in the meeting of hitherto undiscovered hosts and viruses.
The findings was published in the journal Proceedings of the Royal Society B: Biological Sciences, however the scientists are careful to note that they are not predicting either a real spillover or a pandemic.
Lemieux said that “the chance of major developments remains relatively low.”
They also caution that further research is necessary to determine how much variation across viruses and hosts is necessary to pose a significant spillover danger.
However, they believe that rising temperatures may enhance hazards if additional potential hosts relocate into previously inhospitable places.
Lemieux speculated that “everything from ticks and mosquitoes to particular animals to germs and viruses themselves” may be to blame.
It’s so hard to forecast… The impact of a spillover might be anything from a little inconvenience to a global epidemic.
In order to better grasp the hazards, the team is calling for greater study and observation in the area.
We’ve seen in the previous two years what spillover effects may be like,” added Lemieux.
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