DOGS, cats and rabbits could all, theoretically, play host to the same coronavirus that causes Covid-19 in humans.

Scientists at The Pirbright Institute have shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is able to enter cells using the receptors of 'multiple' mammalian species and concluded that the virus has a 'broad host range' in the animal kingdom.

Covid-19 is already recognised as a zoonotic disease that jumped from animals into humans, and identifying the original animal reservoir and intermediate hosts which spread the virus to humans may ultimately help to understand how, where and when this virus jumped the species barrier – knowledge which could be vital in preventing subsequent outbreaks of both related and unrelated viruses.

To enter cells, SARS-CoV-2 uses its spike glycoprotein to bind to ACE2 receptors on the surface of cells in various tissues including the lungs, heart and gastrointestinal tract. Pirbright researchers experimentally infected cells displaying human ACE2 or a panel of related ACE2 receptors from 22 animal species, including birds, rodents, companion animals and livestock.

Their pre-published study demonstrates that the virus works its way into each species differently, but that dog, cat and rabbit ACE2 receptors were utilised most effectively. This efficient entry could potentially correlate with infection being more easily established in these animals.

However, Pirbright stressed that cell entry is only the first step in viral transmission between different animal species. An animal’s susceptibility to infection and its subsequent ability to infect others is reliant on a range of factors such as whether SARS-CoV-2 is able to replicate once inside cells and the animal’s ability to fight off the virus.

Interestingly, although bats are suspected to be the original reservoir of SARS-CoV-2, the Pirbright results show that receptors from three bat species were among those that were least efficiently used by the spike glycoprotein. This is possibly due to adaptations SARS-CoV-2 has made during its zoonotic emergence in order to effectively bind to human ACE2 receptors.

Dr Dalan Bailey, head of the Viral Glycoproteins group at Pirbright said: “Our research identifies species where viral entry is most efficient, allowing scientists to prioritise research on animals that might be susceptible to disease. We also identify animals that could provide good experimental models for understanding Covid-19, such as hamsters and rabbits.”