New York: Ever since the novel coronavirus outbreak in Wuhan
province of China in December, rumour mills were running overtime with conspiracy
theories of a biological warfare. The internet was rife with speculations of
the virus being a mass weapon “accidently spilled out” of a bio-war programme
of the Asian giant itself. It reached a height when Beijing recently pointed fingers
at the United States over the “virus origin”.
Now a new study, published in the journal of Nature Medicine,
seeks to sweep all that notions under the carpet.
"By comparing the available genome sequence data for
known coronavirus strains, we can firmly determine that SARS-CoV-2 originated
through natural processes," said Kristian Andersen, an associate professor
of immunology and microbiology at Scripps Research Institute and corresponding
author on the paper ‘The proximal origin of SARS-CoV-2’.
The disease caused by the novel coronavirus, referred as COVID-19,
so far claimed nearly 9000 lives in over 2,19, 300 cases across the globe. Shortly
after the epidemic began, Chinese scientists sequenced the genome of SARS-CoV-2
and made the data available to researchers worldwide. Andersen and
collaborators at several other research institutions used this data to explore the
origins and evolution of SARS-CoV-2 by focusing in on several tell-tale
features of the virus.
The scientists analyzed the genetic template for spike
proteins, armatures on the outside of the virus that it uses to grab and
penetrate the outer walls of human and animal cells. More specifically, they
focused on two important features of the spike protein: the receptor-binding
domain (RBD), a kind of grappling hook that grips onto host cells, and the
cleavage site, a molecular can opener that allows the virus to crack open and
enter host cells.
The scientists found that the RBD portion of the SARS-CoV-2 spike proteins had evolved to effectively target a molecular feature on the outside of human cells called ACE2, a receptor involved in regulating blood pressure. The SARS-CoV-2 spike protein was so effective at binding the human cells, in fact, that the scientists concluded it was the result of natural selection and not the product of genetic engineering.