Sheep, horses and rabbits are among dozens of domesticated animals that could be susceptible to coronavirus, study shows

  • Researchers used computers to map the  animal versions of ACE2 receptor 
  • It is known that this receptor on human cells is how coronavirus infects cells  
  • Researchers found SARS-CoV-2 can latch onto animal versions as well as human 
  • Found 37 out of 215 studied species are likely at risk of infection from the virus  
  • And 28 are in regular contact with people in either domestic, zoological or agricultural settings 

Dozens of animals which regularly come into close contact with humans are susceptible to infection with the coronavirus, a study shows. 

A total of 28 species were identified as being vulnerable to SARS-CoV-2, the same virus causing the Covid-19 pandemic in humans. 

While it was already known dogs and cats are at risk of infection, the latest research also reveals so too are guinea pigs, rabbits and hamsters.

Outside of a domestic setting, researchers from the University College London (UCL) found animals in zoos (gorillas, polar bears and chimps) and on the farm (goats, donkeys and horses) can also be infected with the coronavirus. 

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Pictured, the species which were identified as being vulnerable to SARS-CoV-2, the same virus causing the Covid-19 pandemic in humans. While it was already known dogs and cats are at risk of infection, the latest research also reveals so too are guinea pigs, rabbits and hamsters

Pictured, the species which were identified as being vulnerable to SARS-CoV-2, the same virus causing the Covid-19 pandemic in humans. While it was already known dogs and cats are at risk of infection, the latest research also reveals so too are guinea pigs, rabbits and hamsters

The scientists are particularly worried about sheep as the virus binds to their cells just as strongly as it does in humans. 'Of particular concern are sheep... as these animals are farmed and come into close contact with humans,' the researchers write in their study

The scientists are particularly worried about sheep as the virus binds to their cells just as strongly as it does in humans. 'Of particular concern are sheep... as these animals are farmed and come into close contact with humans,' the researchers write in their study

Guinea pigs (pictured) are among the animal species at risk of catching the coronavirus, according to the latest research

Guinea pigs (pictured) are among the animal species at risk of catching the coronavirus, according to the latest research 

The study found that most birds, fish, and reptiles do not appear to be at risk of infection, but the majority of the mammals could potentially be infected. 

Researchers investigated the spike protein on the surface of SARS-CoV-2 and how it attaches to animal cells. 

In humans, it latches on to the ACE2 protein which protrudes from the surface of some cells. 

University College London (UCL) scientists looked at variations of ACE2 in 215 species to see if the difference altered susceptibility to the virus. 

They specifically looked at the receptor binding domain (RBD) on the viral spike to see if any mutations prevented infection.  

However, most of the ACE2 equivalents were at least 60 per cent genetically identical to the human version, and of the 215 investigated animals, 37 secies were found to be at risk of infection. 

This included 28 animals that are in close contact with humans and 11 species which are theoretically at risk of infection but unlikely to catch the coronavirus due to a lack of contact with humans, such as dolphins and whales. 

Researchers say that while it is possible the virus might be able to infect animals via another pathway, based on the current evidence it is unlikely it could infect an animal if it cannot bind with ACE2. 

Pictured,a diagram showing the shape and structure of the SARS-CoV-2 virus and its spike
Pictured,a diagram showing the shape and structure of the SARS-CoV-2 virus and its spike

SARS-CoV-2, the virus which leads to Covid-19, has a protein on its surface which binds to a receptor on cells called ACE2 and this is how it invades the body 

horses and donkeys could be infected by the SARS-CoV-2 coronavirus causing the Covid-19 pandemic, scientists say

horses and donkeys could be infected by the SARS-CoV-2 coronavirus causing the Covid-19 pandemic, scientists say 

Outside of a domestic setting, researchers from the University College London (UCL) found animals in zoos (gorillas, polar bears and chimps) and on the farm (goat, donkey and horses) can also be infected with the coronavirus

Outside of a domestic setting, researchers from the University College London (UCL) found animals in zoos (gorillas, polar bears and chimps) and on the farm (goat, donkey and horses) can also be infected with the coronavirus

Mammals which are susceptible to SARS-CoV-2 and in close contact with people 

Zoological 

  1. Leopard 
  2. Arabian camel
  3. Panda 
  4. Polar bear 
  5. Wild yak 
  6. Macaque 
  7. Golden snub-nosed monkey 
  8. Orangutan
  9. Gorilla
  10. Bonobo
  11. Chimp 

Domestic 

  1. Rabbit
  2. Golden hamster  
  3. Dog 
  4. Chinese hamster 
  5. Squirrel 
  6. Guinea pig 
  7. Cat 

Agricultural 

  1. Sheep 
  2. Cow 
  3. Cow hybrid Bos Indicus 
  4. Domestic Yak  
  5. Ferret 
  6. Goat 
  7. Donkey 
  8. Horse 
  9. Pig 
  10. Red fox 

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According to the study published in Scientific Reports, for some animals, such as sheep and great apes (chimpanzee, gorilla, orangutan, and bonobo – many of which are endangered in the wild), the proteins would be able to bind together just as strongly as they do when the virus infects people.

The scientists say that although the findings indicate which animals are at risk of catching the virus, it is not proof and does not confirm they can be infected.

For this, hands on experiments are needed. However, their theoretical findings have been proved right in many species, with infection seen in cows, ferrets and rabbits. 

The scientists are particularly worried about sheep as the virus binds to their cells just as strongly as it does in humans and they regularly come close to people.  

Antibodies from LLAMAS can neutralise the coronavirus 

Antibodies taken from the blood of llamas and engineered to target SARS-CoV-2, the virus which causes Covid-19, could offer a future treatment for the disease. 

Llamas, as well as camels and alpacas, naturally produce very small antibodies, called nanobodies, which are dwarfed by those made by human immune systems. 

Lab-based experiments found these naturally-occurring antibodies can be tailored to neutralise the coronavirus by binding tightly to its 'spike protein' and blocking it from entering human cells. 

The research is still in a very early stage and has seen a rapid turnaround, with academics at the Rosalind Franklin Institute at Oxford University condensing a process which would normally take almost a year into just 12 weeks. 

However, the researchers believe the llama-derived nanobodies could eventually be developed as a treatment for humans struck down with a severe case of Covid-19

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The research opens up the possibility that sheep could be at risk of catching the virus, and also passing the virus on to people, in the same way as was seen at mink farms in the Netherlands.   

Lead author Professor Christine Orengo, of UCL Structural and Molecular Biology, says: '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.'

The researchers also examined certain animals in more detail to gain a better understanding of how infection risks may differ across animal species.

They used pre-existing experimental data which looked at how much energy was expended when the ACE2 receptor binds to the SARS-CoV-2 viral spike. 

The less energy that is spent, the easier the interaction is and the more at risk of infection the species is. 

For sheep and gorillas, for example, there was no difference in energy change when compared to humans, indicating high risk. 

However, the researchers set a threshold for how much energy was likely too much, indicating infection was not possible. 

This figure was derived from that of the horseshoe bat, which researchers already know is definitely able to be infected with the virus.  

It is believed horseshoe bats are immune to coronaviruses, but act as a reservoir for the pathogens. 

Scientists speculate these repositories of disease may have been how the virus first jumped into humans, triggering the entire Covid-19 outbreak which has now killed more than a million people worldwide.

The horseshoe bat's energy measurement is 3.723 kcal/mol, and the researchers set this as the upper threshold. 

Anything with an energy expenditure lower than this is considered to be at risk of infection, while anything higher is deemed to not be at risk. 

For example, dogs (0.45), sheep (0.00) and pigs (1.77) are at risk, whereas mice (5.55), chicken (5.00) and ducks (5.89) are likely to be immune. 

However, the researchers do believe that as more experimental data becomes available, this figure will likely rise, revealing more animals that are at risk.  

Professor Orengo added: 'The details of host infection and severity of response are more complex than just the interactions of the spike protein with ACE2, so our research is continuing to explore interactions involving other host virus proteins.'

The findings mostly agree with experiments conducted in living animals and with reported cases of infections.

Researchers predict possible infection in domestic cats, dogs, mink, lions, and tigers, all of which have had reported cases, as well as ferrets and macaques, which have been infected in laboratory studies.

First author, Su Datt Lam of UCL Structural and Molecular Biology and the National University of Malaysia, said: 'Unlike laboratory-based experiments, the computational analyses we devised can be run automatically and rapidly.

'Therefore, these methods could be applied easily to future virus outbreaks that, unfortunately, are becoming more common due to human encroachment into natural habitats.'

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