It isn’t just humans that are at risk of being infected with the novel coronavirus. New research has sifted through the animal kingdom and worked out which species might be most vulnerable to SARS-CoV-2, the coronavirus that causes Covid-19.
Scientists at UC Davis studied the genome of 410 different vertebrate species, including birds, fish, amphibians, reptiles, and mammals, and found that a wide range of the animals could potentially be susceptible to some kind of SARS-CoV-2 infection.
As per their findings, the animals most vulnerable are members of our wider primate family, including Western lowland gorillas, Sumatran orangutans, Northern white-cheeked gibbons, bonobos, and chimpanzees. Those considered at high risk include a range of mammals, such as beluga whales, narwhals, minke whales, reindeer, orca, and bottlenose dolphins. Animals considered to have a medium risk are sheep, American bison, wild yaks, giraffes, jaguars, leopards, Siberian tigers, and cheetahs. Low-risk animals include grizzly bears, polar bears, dogs, rhinos, horses, and tapirs.
Perhaps most worryingly, around 40 percent of the species potentially susceptible to SARS-CoV-2 are threatened with extinction.
The full list of animals can be found here. The findings were recently reported in the Proceedings of the National Academy of Sciences.
It's possible to estimate how vulernable an animal might be to SARS-CoV-2 by looking at the protein receptors found on some of their cells. The coronavirus breaks into human cells by using its own spike protein to latch onto a specific protein known as ACE2, a bit like a lock and key. The protein ACE2, which is found on the surface of many different types of human cells, is made up of 25 sequences of amino acids (the building blocks of proteins). If an animal cell has a protein that has a similar sequence of amino acids, then it's fair to assume they too will be susceptible to the spike protein of SARS-CoV-2 and vulnerable to infection.
“Animals with all 25 amino acid residues matching the human protein are predicted to be at the highest risk for contracting SARS-CoV-2 via ACE2,” first author Joana Damas, a postdoctoral research associate at UC Davis, explained in a statement. “The risk is predicted to decrease the more the species’ ACE2 binding residues differ from humans.”
However, it remains unclear what exactly this vulnerability to SARS-CoV-2 might entail. For example, a lower propensity for binding might mean a lower propensity for infection. On the other hand, it could indicate a lower ability for the infection to spread in an animal or between animals once established.
So, animal lovers and pet owners do not necessarily need to freak out over these findings, say the researchers. That said, they do hope this research will be used to help people working closely with animals. As you might have read over the past few months, there have been several reports of animals catching the virus. For example, there have been reports of pet dogs being infected with Covid-19 and it was even reported that a tiger tested positive at the Bronx Zoo.
“Zoonotic diseases and how to prevent human to animal transmission is not a new challenge to zoos and animal care professionals,” added co-author Klaus-Peter Koepfli, a senior research scientist at the Smithsonian-Mason School of Conservation and former conservation biologist with the Smithsonian Conservation Biology Institute’s Center for Species Survival and Center for Conservation Genomics. “This new information allows us to focus our efforts and plan accordingly to keep animals and humans safe.”