Understanding the origins of the virus that causes COVID-19 is one of the key questions that scientists are trying to answer when determining how to manage the pandemic. But in a rapidly changing situation, we are forced to point the finger at some innocent suspects along the way.
The current hypothesis looks like this: SARS-CoV-2 passed through a mysterious animal host during its supposed evolutionary journey from bats to humans. The critically endangered pangolins have been a preferred candidate for this intermediate hostBut now, a genomic analysis by geneticist Ping Liu from the Guangdong Academy of Sciences in China has provided evidence that this may not be the case.
SARS-CoV-2 belongs to the Betacoronavirus genus of coronaviruses; This group of coronaviruses mainly infects mammals, and the new study suggests that pangolins are indeed natural hosts for them.
The team reconstructed an almost complete genome of the coronaviruses found in two patients. Malaysian pangolins ((Manis javanica) They called the coronavirus isolated from these critically endangered animals pangolin-CoV-2020. Its final sequence included 29,521 base pairs, just slightly shorter than the 30,000 odd base pairs that make up SARS-CoV-2.
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The resulting genome showed sequence similarity of 90.32% with SARS-CoV-2 and 90.24% with Rhinolophus affinis bat coronavirus BatCoV-RaTG13, which remains the Closest known to SARS-CoV-2, with a correspondence of 96.18%.
But the sequence similarities do not reflect the whole story. Genetic instructions for what matters most SARS-CoV-2 virus protein peak it corresponded more between the bat and the human coronavirus than the pangolin.
However, the pangolin virus basically shares the same ACE2 link receiver like that used by the COVID-19 virus, the part of the tip that allows the virus to enter and infect human cells. This was also found in another study which is still under study, and leads to suggestions
that the human coronavirus can be a type of hybrid (a chimera) between a bat and a pangolin virus.
Liu's team also believes that these similarities may indicate that a recombination event occurred somewhere in the evolution of these different viruses, where viral genomes have exchanged between them. parts of their genetic material. However, his analysis of the evolutionary relationship between the three viruses did not support the idea that the human version evolved directly from pangolin.
"At the genomic level, SARS-CoV-2 was also genetically closer to Bat-CoV-RaTG13 than to pangolin-CoV-2020." they wrote in his role
Obviously, there are still many unknowns. With more than 4 million confirmed cases Around the world, and the number of deaths continues to increase dramatically, the need to understand as much as possible this virus continues to escalate.
However, one thing that all of these genetic studies have firmly rejected is the idea that the the virus was made in the laboratory.
As for the pangolins, they were rescued by the Guangdong Wildlife Rescue Center after being smuggled for the black market, and unfortunately died from their illness. Liu's team could not determine if their death was related to the coronavirus they had found.
But maybe something good can come from all of this, at least for him. most trafficked in the world
"Minimizing exposure of humans to wildlife will be important to reduce the risk of contagion of coronaviruses from wildlife to humans."
The new research was published in PLOS pathogens.