After humans, ferrets, cats, civets, and dogs are the most susceptible animals to Covid-19, according to an analysis of 10 different species of animals by researchers.
The researchers at the Centre for Genomic Regulation (CRG), based in Barcelona, stated in their study, published in PLOS Computational Biology, that ducks, rats, mice, pigs and chickens had lower or no susceptibility to infection compared to humans.
Senior author of the study, Luis Serrano, ICREA Research Professor, Director of the CRG, said: “Knowing which animals are susceptible to SARS-CoV-2 helps us prevent building up animal reservoirs from which the coronavirus can re-emerge at a later date.”
“Our findings offer a clue for why minks — which are closely related to the ferret — are being infected by the disease, which is probably made worse by their packed living conditions and close contact with human workers.”
“Though we also find a potential susceptibility to infection by cats, they don’t co-exist with humans in the same conditions as other animals, which may explain why so far there are no known cases of people being infected by their pets,” noted Dr Serrano.
Researchers mentioned that ten species were studied in this paper. Five species — humans, cats, ferrets, civets, and dogs — have had documented cases of infection by SARS-CoV-2. There are no reports of infection in the other five species — mice, rats, pigs, chickens, and ducks.
For the study, the researchers used computer modelling to test how the coronavirus uses its spike proteins to infiltrate the cells of different animals. The main point of entry on a cell’s surface is the ACE2 receptor, which binds with the spike protein and helps the virus gain entry to host cells.
Variants of the ACE2 receptor in humans followed by ferrets, cats, dogs, and civets have the highest binding affinities to the viral spike protein while mice, rats, chickens, and ducks have poor binding energy.
The researchers further assessed different species’ ‘codon adaptation index’ — which is how efficient the coronavirus is at commandeering a cell’s machinery once it has entered. The more efficient the process, the better the coronavirus can create the proteins it needs to replicate.
Humans, chickens, and ducks have the highest codon adaptation index, while the other species are worse adapted, the researchers added in their study.