Pangolins unlikely to be the intermediate host for the emergence of Covid 19, researchers have found
Initial research has suggested pangolins, the most heavily trafficked mammal in the world, may have served as an intermediate host in the transmission of the novel coronavirus from bats to humans.
But researchers at the Guangdong Academy of Science in China say that while the pangolin coronavirus is genetically related to Sars-CoV-2 and to certain bat coronaviruses, it is not behind the global pandemic, which has infected over 4 million people and killed 300000.
Geneticist Ping Liu led the study, “Are pangolins the intermediate host of the 2019 novel coronavirus (Sars-CoV-2)?”, which was published this week in the journal, PLOS Pathogens.
The goal of the study was to determine the genetic relationship between a coronavirus from two groups of sick pangolins and Sars-CoV-2, and to assess whether pangolins could be potential intermediate hosts of Sars-CoV-2.
The Guangdong research team sequenced the entire genome of a coronavirus identified in the two groups of sick Malayan pangolins, likely smuggled for the black market trade.
“The molecular and phylogenetic analyses showed that this pangolin coronavirus (pangolin-CoV-2020) is genetically related to the Sars-CoV-2 as well as a group of bat coronaviruses but do not support the Sars-CoV-2 emerged directly from the pangolin-CoV-2020.”
Pangolins could be natural hosts of Betacoronaviruses “with an unknown potential to infect humans,” the study says. “However, our study does not support that Sars-CoV-2 evolved directly from the pangolin-CoV Although this present study does not support that pangolins would be intermediate hosts for the emergence of Sars-CoV-2, our results do not exclude the possibility that other CoVs could be circulating in pangolins.”
Surveillance of coronaviruses in pangolins could improve the understanding of the spectrum of coronaviruses in pangolins, the paper says.
In addition to conservation of wildlife, minimising the exposures of humans to wildlife “will be important to reduce the spillover risks coronaviruses from wild animals to humans”.
Determining the spectrum of coronaviruses in pangolins can help understand the natural history of coronaviruses in wildlife and at the animal-human interface, and facilitate the prevention and control of coronavirus-associated emerging diseases, the researchers write.
Coronaviruses are shown to have a wide range of hosts, and some of them can infect humans. It is critical, the researchers state, to determine the natural reservoir and the host tropisms of these coronaviruses, especially their potential of causing zoonotic diseases - infectious diseases caused by a pathogen that has jumped from an animal to a human.
The study states how the novel coronavirus has been associated with an epidemiological link to the Huanan Seafood Wholesale Market, a local live animal and seafood market in China.
“To effectively control the disease and prevent new spillovers, it is critical to identify the animal origin of this newly emerging coronavirus. In the Wuhan wet market, high viral loads were reported in environmental samples.
“However, a variety of animals, including wildlife, were sold in this market, and the daily number and species of animals were very dynamic. Therefore, it remains unclear which animals initiated the first infections.”