DAVIS, Calif. — With nearly 23 million coronavirus cases around the world, it could be easy to forget humans aren’t the only ones affected by this pandemic. A new study reveals several animal species are at risk from the illness too. Researchers say animals which share a particular gene the virus attacks in humans are more vulnerable. Making the problem even worse, some of the most vulnerable are also on the endangered species list.
The University of California, Davis reports SARS-CoV-2, the virus which causes COVID-19, binds itself to the ACE-2 gene on the surface of cells. SARS-CoV-2 uses its “spike” protein to grab onto these genes and slice through the cells. From there, they hijack a cell’s ability to reproduce and start replicating more of the virus.
An international team of scientists compared the ACE-2 receptor in 410 different species of vertebrates (animals with backbones). The analysis looks at how this cellular receptor differs chemically in birds, fish, amphibians, reptiles, and mammals.
Not all ACE-2 genes are the same
The study in the journal Proceedings of the National Academy of Sciences explains ACE-2 is commonly found on cells in the human nose, mouth, and lungs. There are 25 amino acids in them which are important to SARS-CoV-2 and helps the virus bind to human cells.
Looking at these amino acids and their reaction to the coronavirus spike protein, the team finds species which share some or all of these compounds with humans are at a higher risk for contracting COVID-19.
“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,” says study author Joana Damas in a university statement. “The risk is predicted to decrease the more the species’ ACE2 binding residues differ from humans.”
Danger for ‘threatened’ species
Study authors say 40 percent of the animals which may be susceptible to SARS-CoV-2 are considered “threatened” by the International Union for Conservation of Nature. These species may be extremely vulnerable to human-animal transmission.
Critically endangered primates are among the most at risk from coronavirus. The Western lowland gorilla, Sumatran orangutan, and Northern white-cheeked gibbon all share similarities in their ACE2 receptors with humans.
Land species aren’t the only ones the pandemic can seriously affect. The study reports marine mammals like the gray whale and bottlenose dolphin are also in the high risk category.
Are your pets at risk from COVID-19?
Scientists reveal that common household pets and farm animals tend to have a lower risk of having SARS-CoV-2 bind to their ACE-2 receptors. Cats, cattle, and sheep are in the medium risk range, while dogs, horses, and pigs have low risks of infection.
Study authors add that previous SARS-COV-2 infections in cats, dogs, hamsters, lions, and tigers may have entered cells through ACE-2. They caution that it’s also possible the virus uses other genes to enter animal cells.
This lower risk of infection among pets echoes previous studies which find animals like cats pose very little risk of infecting humans.
Protecting animal population from coronavirus
On the other hand of this vulnerability spectrum, humans still pose a major risk to species they have contact with. Institutions like the National and San Diego Zoos are strengthening their protocols to help protect their animals from the pandemic.
“Zoonotic diseases and how to prevent human to animal transmission is not a new challenge to zoos and animal care professionals,” explains co-author Klaus-Peter Koepfli. “This new information allows us to focus our efforts and plan accordingly to keep animals and humans safe.”
The report says more testing on these genetic differences need to be made. They caution against overinterpreting this data in an attempt to predict which animals can or cannot transmit SARS-CoV-2. Researchers point to the suspected origin of the pandemic, the bat. Although they’re in the very low range for contracting COVID-19, they may have given it to humans, sparking this crisis.