- Although SARS-CoV-2 has zoonotic origins, scientists weren't sure how the virus affected other animals
- Sporadic reports of domestic pets testing positive for the virus made them realise that the virus could be passed from human to animal
- This means that more mammal species could be susceptible to the virus
When headlines of the novel coronavirus, known as SARS-CoV-2, began to surface, there were reports of a domestic cat and a tiger at a zoo in New York testing positive for the virus.
We already knew that the virus was zoonotic in origin, even if we were not quite sure if it came from a bat or a pangolin.
But as the virus progressed, we started hearing more about domestic animals testing positive for SARS-CoV-2. Researchers found that a substantial number of dogs and cats were infected with SARS-Cov-2 along with their owners, according to a Health24 article.
Now, a new study conducted by UCL researchers and published in Scientific Reports, found that as many as 26 species of animals that have regular contact with humans may be susceptible to SARS-CoV-2
Spike protein investigated
For this study, the researchers investigated how the spike protein from SARS-CoV-2 interacts with the ACE2 protein it attaches to when the virus enters the bodies of humans.
The researchers wanted to see whether mutations in the ACE2 protein in 215 different animal species could cause the virus to be less susceptible to binding its spike protein to the ACE2 protein.
As soon as the spike protein binds to the ACE2 protein in the host, the virus starts attacking various cells, which causes illness. It’s largely the presence of the ACE2 protein in various organs in our bodies that explains why Covid-19 causes such an array of symptoms.
And in some animals such as sheep and the great apes (chimpanzee, orangutan and gorilla), the spike proteins have the same ability as in humans to form a strong tie with the ACE2 protein, making these animals more likely to be infected with SARS-CoV-2.
Instead of doing experiments, the researchers analysed the sequence similarity between the ACE2 protein in humans and other species.
They then did computational analyses to investigate the likelihood of the SARS-CoV-2 spike protein attaching to various versions of ACE2 protein.
According to Professor Christine Orengo from the department of Structural and Molecular Biology at UCL, the purpose of the study was to look beyond the animal species that were studied experimentally to determine which ones may be at risk.
The researchers found that the majority of mammals, especially those regularly in contact with humans, could potentially be infected. Birds, reptiles and fish, however, didn’t appear to be at risk of infection, they stated.
"The animals we identified may be at risk of outbreaks that could threaten endangered species or harm the livelihoods of farmers. The animals might also act as reservoirs of the virus, with the potential to re-infect humans later on, as has been documented on mink farms,” said Prof Orengo.
What does this study mean for humans and animals?
According to the researchers, the implication of SARS-CoV-2 and how it’s transferred between humans and animals is important for future management.
"To protect animals, as well as to protect ourselves from the risk of one day catching Covid-19 from an infected animal, we need large-scale surveillance of animals, particularly pets and farm animals, to catch cases or clusters early on while they're still manageable,” said co-author Professor Joanne Santini, also from UCL.
"It may also be important to employ hygiene measures when dealing with animals, similar to the behaviours we've all been learning this year to reduce transmission, and for infected people to isolate from animals as well as from other people."
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