Pangolins are natural hosts for coronaviruses. However, there is no evidence that they played the intermediaries in the transmission of SARS-CoV-2 in humans.
Recent studies have shown that bats may be the main reservoir for SARS-CoV-2, which is responsible for the Covid-19 pandemic. In contrast, in these winged mammals, the virus does not have receptors that allow it to “attach” to a human host. In other words, to infect humans, SARS-CoV-2 had to go through an intermediate species. But which? If we are to effectively control the disease and prevent further outbreaks, it will be essential to answering this question.
For the past few weeks, attention has been focused on pangolins. And for good reason, hunted for their scales, which according to practitioners of traditional medicine would have certain virtues for health, these animals have been for several decades, and despite themselves, in close contact with humans. Nevertheless, did they really play the intermediaries?
A study published at the end of March in the journal Nature focused on samples taken from 18 Malaysian pangolins. The latter comes from operations to combat smuggling in southern China between August 2017 and January 2018. However, these samples revealed the presence of SARS-CoV-2-related coronaviruses in five of them.
However, the degree of similarity was not sufficient to confirm that pangolins were directly involved in the transmission of SARS-CoV-2 to humans. A new genetic analysis by researchers at the Guangdong Institute for Applied Biological Resources (China) seems to point in the same direction.
A still-mysterious origin
This work appears in the journal PLOS Pathogens. Researchers analyzed the genome of a coronavirus identified in three sick Malaysian pangolins. The latter were rescued by the Guangdong Wildlife Rescue Center after being smuggled for the Chinese black market. As a result, they, unfortunately, died of their illness.
That said, the results of this study again show that the pathogen is genetically similar to SARS-CoV-2, as well as to another group of coronaviruses identified in bats (BatCoV-RaTG13), but that ‘he is probably not his forerunner.
The resulting genome had a 90.32% sequence similarity to SARS-CoV-2. It was 90.24% with the BatCoV-RaTG13 coronavirus found in the bat species Rhinolophus affinis. It remains the closest known to SARS-CoV-2, with correspondence of 96.18%.
This study, therefore, does not support the idea that pangolins are the intermediate hosts responsible for the emergence of SARS-CoV-2. However, it is possible that other coronaviruses with unknown infectious potential circulate in these animals which are naturally carriers.
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