Mutation increased SARS-CoV-2’s ability to target human cells, which partly explains its faster spread, according to a research
The novel coronavirus disease (COVID-19) cause by SARS-CoV-2 virus has affected more than half-a-million people across the globe, as on early March 27, 2020.
The numbers have been increasing by the hour, with the United States recording the maximum positive cases in the world. Italy and Spain in Europe continue to be the most affected, with more than 8,000 and 4,000 deaths respectively till March 27.
It is important to understand the origins of SARS-CoV-2 virus in order to deconstruct it and find a cure for COVID-19.
A research published in the journal Pathogen on March 20, 2020 suggested that the virus likely jumped to humans from pangolins, one of the most trafficked animals in the world.
Pangolins are illegally sold in the wildlife markets of China such as the Huanan market in Wuhan city. Most initial positive COVID-19 cases were linked to Wuhan, which was the epicentre of the outbreak till a few weeks ago.
SARS-CoV-2 has spike proteins which contain a receptor-binding domain (RBD).
The RBD facilitates the virus’ entry into target cells by binding with the angiotensin-converting enzyme-2 (ACE-2) found in heart, lungs, kidneys and the gastrointestinal tract.
According to research, RBD of the SARS-CoV-2 could be a mutated version of RBD of the RaTG13 virus, found in a species of bat of scientific name Rhinolophus affinis. The species were found in the Yunan province of China. In fact, the two viruses share an overall genetic similarity of 96 per cent.
Another virus with greater genetic similarity to SARS-CoV-2’s RBD is found in Malayan pangolins.
According to the research, the mutation increased the RBD’s bonding affinity with the ACE-2 of target cells in humans, ferrets and Malayan Pangolins.
This bonding is stronger in SARS-CoV-2 virus than it was in SARS-CoV virus, which caused the SARS [Severe Acute Respiratory Syndrome] epidemic in 2002-2003 across 29 countries. The stronger bonding affinity partly explains CoVID-19’s faster spread.
According to a research paper published in Nature Medicine on March 17, 2020, the original source of the virus was bats, and pangolins might have acted as intermediaries. The mutation and natural selection might have taken place either inside pangolins or in humans after transfer from pangolins.
An article published in The Conversation suggested that SARS-CoV-2 could be a recombinant organism formed by the genetic mix-up of two different viruses infecting the same carrier animal.
This is because none of the known coronaviruses seemed to be the parent virus which got mutated to give birth to SARS-CoV-2.
Such mechanisms have also been put forth for the origin of other coronaviruses like the SARS-CoV virus.
In the initial days of the outbreak, it was speculated that SARS-CoV-2 was deliberately genetically engineered. However, there is no evidence to support the claim so far.
Another paper published in Nature stated that the mutation was different from what was predicted from previously known genetic systems.
The research is on, and sooner or later, the world will hopefully know the truth abouth the virus.
Most papers mentioned above are not peer-reviewed.
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