Scientists on Genetic Quest to Understand Covid-19

(CN) – Stop eating scaly anteaters. That is one of the conclusions, published in the journal Nature on Thursday, drawn by more than a dozen Chinese researchers who found two lineages of coronaviruses in smuggled pangolins with striking similarities to the pandemic respiratory disease Covid-19.

By the World Wildlife Federation’s count, pangolins — scaly anteaters — are one of the most trafficked animals in the world, particularly in China and Vietnam where the meat is consumed as a delicacy and the scales used as an ingredient in traditional medicine.

A pangolin carries its baby at a Bali zoo in Bali, Indonesia. (AP Photo/Firdia Lisnawati, File)

As of March 25, the World Health Organization reported 466,633 people have been diagnosed with the highly contagious coronavirus Covid-19, of which 21,145 have reportedly died.

The outbreak can be traced back to the Huanan seafood and wildlife market in Wuhan city, China, where researchers believe the zoonotic disease jumped from a wild animal to the first humans this past December.

“The role that pangolins play in the emergence of SARS-CoV-2 (the cause of Covid-19) is still unclear,” said one of the paper’s authors, Australian evolutionary virologist Edward Holmes, in a statement accompanying the study. “However, it is striking that the pangolin viruses contain some genomic regions that are very closely related to the human virus. The most important of these is the receptor binding domain that dictates how the virus is able to attach and infect human cells.”

Researchers found six coronaviruses in lung, intestine, and blood samples from 18 Malayan pangolins collected toward the end of 2017 during an anti-smuggling operation. Among 12 other animals collected in the summer of 2018, researchers found three pangolins positive for coronaviruses.

The coronaviruses found in the pangolins are 85.5% to 92.4% genetically similar to the disease currently spreading among humans. Although similarities were also found among coronaviruses in bats, the Guangdong pangolin coronaviruses “possess identical amino acids at the five critical residues of the receptor-binding domain” as the virus found in humans.

Understanding the evolutionary pathway of these viruses is important not only to help curb the spread of this current pandemic, but also to help identify future threats in other species.

A Centers for Disease Control and Prevention illustration of the 2019 Novel Coronavirus (2019-nCoV). (CDC via AP, File)

“It is clear that wildlife contains many coronaviruses that could potentially emerge in humans in the future,” Holmes explained. “A crucial lesson from this pandemic to help prevent the next one is that humans must reduce their exposure to wildlife, for example by banning ‘wet markets’ and the trade in wildlife.”

Popular throughout Asia and Latin America, wet markets are street-level markets that sell live animals, fish, produce and other perishable goods for human consumption. A 2007 study identified wet markets as a “time bomb” because “large numbers and varieties of these wild game mammals in overcrowded cages and the lack of biosecurity measures in wet markets allowed the jumping of this novel virus from animals to human.”

The researchers also call for action against illegally trafficked exotic animals and better surveillance of bats and other animals that carry similar diseases.

Funding for the research included grants from National Key Plan for Scientific Research and Development of China as well as the Australian Research Council.

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