Researchers of the University of Calgary in Canada, suspect that the novel Coronavirus (SARS-CoV-2) might be in evolution among humans since around 2013. But it might not be the same strain that is causing this COVID-19 pandemic.
Six strains of Coronavirus wereCoronavirus commonly prevalent among animals. But the seventh strain is an anonymous strain that is wreaking havoc in the form of COVID-19 and causing a global catastrophe by infecting the human population in the mass.
While scientists throughout the world are working hard to figure out the virus, its effects, origin, and cure, the World Health Assembly had passed a resolution to find the source of the strain.
There are multiple theories of origin. One, the virus got transferred from an animal to a human. Two, it was artificially developed in a laboratory in china for some medical reasons. However, studies rule out this possibility by saying the origin is natural and not human-made.
Recently, a team of researchers at the University of Calgary in Canada say that the SARS-CoV-2 might have been in circulation among humans beginning from as early as 2013. However, it would not be the same strain responsible for the pandemic. They have submitted their report at the Biorxiv, but the findings of the research have not yet been reviewed by the peers.
It is upon the survival mechanism of the viruses that they keep evolving with the changes with the host organism, i.e., if the host evolves, the virus evolves too. So, when the virus jumped from an animal to human, it would nave underwent genetic modification that would produce a new strain of the same virus, only that now it is more powerful and infective. This implies the virus that had mild or no effect on the animal host may have enormous impacts on the human host. For example, the strain of the virus in the bats did not affect the bats, as their immune system was equipped to co-exist with the virus. However, once it jumped hosts, we obviously tend to fall sick.
What does the Canadian Study say?
The study was conducted by the University of Calgary in Canada between 30 December 2019 to 20 March 2020, when they collected about 479 genome sequences of the novel Coronavirus to study its phylogeny. Phylogeny is the study of the evolutionary development of the virus and its relation to other closely related viruses.
The researchers examined the spike protein of the strain of SARS-CoV-2 and how it attaches to the receptors in the human body. This attachment of the novel Coronavirus and the receptors to the human cells determine how the virus invades the healthy tissues. They found 16 variant strains of the virus and about 11 missense mutations out of the 479 genomes. A mutation is when a single nucleotide change makes the DNA/RNA code for a different protein. Thus, some of them gave rise to a separate phylogenetic tree.
Another one of their findings included that the SARS-CoV-2 might be a combination of both bat virus and the pangolin virus. The study found that the genome of novel coronavirus matched 96 percent with that of bat virus and 90 percent with that of the pangolin virus. They predict that this variant might have developed due to a co-infection in the host.
To trace the origin of this novel Coronavirus, the researchers created an ancestral sequence of the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 and labeled it N1. RBD is the part of the spike protein that actually binds with the receptor. The animal virus, which is the common ancestor, was labeled N0.
With what they discovered in the experiment, the scientists concluded that the binding affinity of SARS-CoV-2 might not be a determinant of its infectivity. Further, they predict that there should be some other factors that increased their infectivity in humans. The main conclusion is that the ancestral virus could have been infecting humans too, but with unnoticeable symptoms.