Pangolins that were smuggled into China carry coronavirusesthat are closely related to the one behind the COVID-19 pandemic, according toa study which sheds more light on the origins of the deadly virus.
However, the study, published in the journal Nature, saidthe degree of similarity between the virus in the small anteater mammals, andthe one causing the pandemic is not sufficient to suggest that the animals arethe intermediate hosts behind the current outbreak.
According to the researchers, including those from TheUniversity of Hong Kong, the findings suggest that pangolins are a secondmammalian host of coronaviruses.
They said the sale of pangolins in wildlife markets shouldbe strictly prohibited to minimise the risk of future virus transmission tohumans.
While evidence suggests that bats may be the reservoir forthe pandemic causing virus, SARS-CoV-2, the researchers said the identity ofintermediate host animals — that could have facilitated its transfer to humans— remains unknown.
A seafood market linked to early cases of the recentoutbreak of respiratory disease was cleared out shortly after the outbreakbegan, the scientists said, impeding the search for the animal species that isthe source of the coronavirus.
One possible host, they said, are pangolins — themost-commonly illegally trafficked mammal, that are used both as food and intraditional medicine.
In the study, Yi Guan and his colleagues analysed samplestaken from 18 Malayan pangolins that were obtained from anti-smugglingoperations in southern China between August 2017 and January 2018.
They detected SARS-CoV-2-related coronaviruses in 5 of theseanimals.
On further analysis, they reported the presence of similarcoronaviruses in three out of 12 additional animals seized in a second provincein 2018, and in an additional animal from a third province from which a samplewas collected in 2019.
The viruses isolated from these samples have a sequencesimilarity of approximately 8592 per cent to SARS-CoV-2, the study noted.
One virus, the scientists said, shows strong similarity inthe sequence of the receptor-binding domain — a region that encodes the spike’of the virus that facilitates entry into host cells.
However, they said all of the pangolin coronavirusesidentified to date lack a specific alteration in their sequences that is seenin human SARS-CoV-2.
They said this places uncertainty on their role in thetransmission of the novel coronavirus into humans.
According to the researchers, pangolins are the only mammalsother than bats that have been found to be infected with a SARS-CoV-2-relatedcoronavirus.
Based on the findings, they said there is a potentiallyimportant role for pangolins in the ecology of coronaviruses.
However, the scientists said pangolins cannot be directlyimplicated in the transmission of SARS-CoV-2 to humans.
They said these mammals should be handled with caution,suggesting that further monitoring of pangolins is needed to understand theirrole in the emergence of coronaviruses with the potential to infect humans.
“The discovery of multiple lineages of pangolincoronavirus and their similarity to SARS-CoV-2 suggests that pangolins shouldbe considered as possible hosts in the emergence of novel coronaviruses, andshould be removed from wet markets to prevent zoonotic transmission,” theresearchers wrote in the study.