A team of scientists from Duke University, Los Alamos National Laboratory, the University of Texas at El Paso and New York University who is studying the origins of SARS-CoV-2, the virus that causes COVID-19, found that it shape shifts to jump from animals to humans while gaining the ability to infect human cells.
The genetic analysis of the virus the researchers conducted revealed that its ability to infect humans was gained by evolving a critical gene fragment from a coronavirus that infects pangolin, making it possible to infect humans.
Coronavirus Shapeshifts to Infect Human Cells
The researchers said that the jump from species to species was the result of the ability of the virus to bind to the host cells by altering its genetic material, reports Deccan Chronicle. It is as if the virus retooled the key that allows it to bind to the host cell or, in this case, the human cell, while SARS-CoV-2's "key" is a spike protein found on its surface that they use to attach to cells and infect them.
Dr. Feng Gao, a professor of medicine in the Division of Infectious Diseases at Duke University School of Medicine, said that "very much 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 enabled it to eventually infect humans."
Tracing the virus's evolutionary pathway will help deter future pandemics that may arise from the virus and possibly aid research on a vaccine.
Their current study suggests that the typical pangolin coronaviruses are too different from SARS-CoV-2. That means that they do not directly cause the current pandemic crisis. But they still have the spike protein necessary to bind to the cell membrane, which plays a vital role in infecting humans.
Furthermore, the binding site makes it possible to affix to a cell surface protein commonly found on the human respiratory system, intestinal epithelial cells, endothelial cells, and kidney cells.
On the other hand, the virus in bats is considered the most closely related coronavirus to SARS-CoV-2, but the study noted that its binding site is very different. They said that the virus would not be able to efficiently infect human cells with its binding site if it's on its own.
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A Hybrid Between Bat and Pangolin Viruses
According to the researchers, the novel coronavirus could be a hybrid between the bat and pangolin viruses to gain the "key" needed for the receptor to bind on human cells.
Study co-author Xiaojun Li from Duke University said that there are regions of the virus with a very high degree of similarity of amino acid sequences among different coronaviruses that infect the humans, bats, and pangolins. This suggests that the viruses are under similar host selection that may have caused the early coronavirus to jump from these animals to humans.
Although the researchers have already looked at the coronavirus sequences sampled from pangolins, the scientific community is still divided on whether they played a role in the evolution of the SARS-CoV-2.
The study had already demonstrated that SARS-CoV-2 has a rich evolutionary history. This includes a reshuffling of genetic material between bat and pangolin coronavirus before it gained its ability to be transmissible to humans, said study co-lead author Elena Giorgi, a staff scientist at Los Alamos National Laboratory.
