How he decoded the coronavirus from animals to humans: study
The researchers, including those at the University of Texas at El Paso in the United States, performed a genetic analysis of the new coronavirus and its similar variants in animals, and confirmed that its closest relative is a coronavirus that infects bats.
In the study, published in the journal Science Advances, they said the virus’s ability, SARS-CoV-2, to infect humans was gained by exchanging a critical genetic fragment of a coronavirus that infects a squamous mammal called pangolin.
The researchers reported that this jump from species to species was the result of the virus’s ability to bind to host cells through alterations in its genetic material.
By analogy, they said, it is as if the virus rearranged the key that allows it to open the door of a host cell.
In the case of SARS-CoV-2, the researchers said this “key” is a spike protein found on the surface of the virus, which it uses to bind to cells and infect them.
“Like the original SARS that jumped from bats to civets, or MERS that went from bats to dromedary camels, and then to humans, the progenitor of this pandemic coronavirus underwent evolutionary changes in its genetic material that allowed it to eventually infect humans,” said study co-author Feng Gao of Duke University in the United States.
Tracking the virus’s evolutionary pathway, Gao and colleagues say, can help deter future virus-derived pandemics and possibly guide vaccine research.
In the current study, researchers found that typical pangolin coronaviruses are too different from SARS-CoV-2 to have directly caused the human pandemic.
However, they said that pangolin coronaviruses contain a receptor binding site, a part of the spike protein necessary to bind to the cell membrane, which is important for human infection.
This binding site, according to the study, makes it possible to attach to a cell-surface protein that is abundant in human respiratory and intestinal epithelial cells, endothelial cells, and kidney cells.
While the bat’s viral ancestry is the coronavirus most closely related to SARS-CoV-2, its binding site is very different, the study noted.
On their own, the scientists said, the virus cannot effectively infect human cells with this binding site.
They said the new coronavirus could be a hybrid between the bat and pangolin viruses to obtain the “key” receptor-binding site necessary for human infection.
“There are regions of the virus with a very high degree of amino acid sequence similarity between divergent coronaviruses that infect humans, bats, and pangolins, suggesting that these viruses are under similar host selection and may have made the ancestor of SARS- CoV-2 capable of easily jumping from these animals to humans, “said study co-author Xiaojun Li of Duke University.
While people had already looked at the coronavirus sequences taken from pangolins, the researchers said the scientific community was still divided on whether they played a role in the evolution of SARS-CoV-2.
“In our study, we showed that SARS-CoV-2 indeed has a rich evolutionary history that included a reorganization of genetic material between the bat and pangolin coronavirus before it acquired its ability to jump into humans,” he said. study co-author Elena Giorgi. from Los Alamos National Laboratory in the United States.