There is a chance that the SARS-CoV-2 virus could pass from humans to other susceptible animals.
COVID-19 has been wreaking havoc for months around the planet, sickening nearly 24 million people and taking upwards of 800,000 lives (and counting). Yet humans aren’t the only species susceptible to the novel coronavirus, dubbed SARS-CoV-2, that causes COVID-19, scientists say.
There have been reported cases of pets, including cats and dogs, testing positive for the virus over the past few months, but many other animals, too, may be at risk, according to an international team of experts who analyzed genomes to compare the main cellular receptor for the virus in humans (angiotensin converting enzyme-2, or ACE2) in 410 different species of vertebrates, including birds, fish, amphibians, reptiles and mammals.
ACE2 serves as a receptor on various types of cells and tissues, including epithelial cells in the nose, mouth and lungs. The coronavirus exploits 25 amino acids of the receptor’s protein to latch onto cells and gain entry into them in humans.
This means that animals whose cells have all 25 amino acid residues matching the human protein are at the highest risk of contracting SARS-CoV-2, say the scientists, who published their findings in a paper. “The risk is predicted to decrease the more the species’ ACE2 binding residues differ from humans,” says Joana Damas, a postdoctoral research associate at the University of California, Davis, who was the study’s first author.
“Among the species we found with the highest risk for SARS-CoV-2 infection are wildlife and endangered species. These species represent an opportunity for spillover of SARS-CoV-2 from humans to other susceptible animals,” Damas and her colleagues write.
In all, around 40% of the species that may be susceptible to SARS-CoV-2 are listed as “threatened” by the International Union for Conservation of Nature (IUCN). They include such critically endangered primates as the western lowland gorilla, Sumatran orangutan and northern white-cheeked gibbon.
This means that human contact with these animals, both in zoos and in the wild, should be either eliminated or conducted with safeguards that can ensure the virus cannot spread to nonhuman hosts. Just as we contracted the virus directly from animals, most likely bats, we can pass it on to other animals, including primates.
“Zoonotic diseases and how to prevent human to animal transmission is not a new challenge to zoos and animal care professionals,” says Klaus-Peter Koepfli, a senior research scientist at Smithsonian-Mason School of Conservation. “This new information allows us to focus our efforts and plan accordingly to keep animals and humans safe.”
The scientists caution, however, that further experimental data are needed to confirm that the virus can indeed sicken primates such as gorillas and orangutans. “Given the limited infectivity data for the species studied, we urge caution not to overinterpret the predictions of the present study,” they write.