COVID-19 Coronavirus Epidemic Has A Natural Origin Covid-19 Epidemic

The novel SARS-CoV-2 coronavirus that emerged inside the city on Wuhan, China, previous year including has since caused a large scale COVID-19 epidemic including spread to more than 70 other countries is the product on natural evolution, according to findings published today inside the magazine Nature Medicine.

The analysis on public genome succession data from SARS-CoV-2 including associated viruses found no evidence that the virus was made inside a laboratory or otherwise engineered.

"By comparing the accessible genome succession data for known coronavirus strains, we can firmly determine that SARS-CoV-2 originated through natural processes," said Kristian Andersen, PhD, an couple don on immunology including microbiology at Scripps Research including corresponding writer on the paper.

In addition to Andersen, authors on the paper, "The proximal beginning on SARS-CoV-2," include Robert F. Garry, on Tulane University; Edward Holmes, on the University on Sydney; Andrew Rambaut, on University on Edinburgh; W. Ian Lipkin, on Columbia University.

Coronaviruses are a large family on viruses that can cause illnesses ranging widely inside severity. The first known serious illness caused through a coronavirus emerged in the company of the 2003 Severe Acute Respiratory Syndrome (SARS) epidemic inside China. A second outbreak on serious illness began inside 2012 inside Saudi Arabia in the company of the Middle East Respiratory Syndrome (MERS).

On December 31 on previous year, Chinese authorities alerted the World Health Organization on an outbreak on a novel strain on coronavirus causing serious illness, which was later christened SARS-CoV-2. As on February 20, 2020, nearly 167,500 COVID-19 cases have been documented, although many more mild cases have likely gone undiagnosed. The virus has killed over 6,600 people.

Shortly after the epidemic began, Chinese scientists sequenced the genome on SARS-CoV-2 including made the data accessible to researchers worldwide. The resulting genomic succession data has shown that Chinese authorities quickly detected the epidemic including that the number on COVID-19 cases have been increasing because on anthropoid to anthropoid spread after a single introduction into the anthropoid population. Andersen including collaborators at several other research institutions worn this sequencing data to explore the origins including evolution on SARS-CoV-2 through focusing inside on several tell-tale features on the virus.

The scientists analyzed the genetic template for spike proteins, armatures on the outside on the virus that it uses to grab including pierce the outer walls on anthropoid including animal cells. More specifically, they focused on two important features on the spike protein: the receptor-binding domain (RBD), a kind on grappling hook that grips onto proprietor cells, including the cleavage site, a molecular can opener that allows the virus to break open including enter proprietor cells.

Evidence for natural evolution

The scientists found that the RBD portion on the SARS-CoV-2 spike proteins had evolved to effectively target a molecular feature on the outside on anthropoid cells called ACE2, a receptor involved inside regulating blood pressure. The SARS-CoV-2 spike protein was so effective at compulsory the anthropoid cells, inside fact, that the scientists concluded it was the result on natural choosing including not the product on genetic engineering.

This evidence for natural evolution was supported through data on SARS-CoV-2's backbone -- its overall molecular structure. If someone were seeking to engineer a new coronavirus while a pathogen, they would have constructed it from the backbone on a virus known to cause illness. But the scientists found that the SARS-CoV-2 backbone differed substantially from those on already known coronaviruses including mostly resembled associated viruses found inside bats including pangolins.

"These two features on the virus, the mutations inside the RBD portion on the spike protein including its distinct backbone, rules out laboratory manipulation while a potential beginning for SARS-CoV-2" said Andersen.

Josie Golding, PhD, epidemics lead at UK-based Wellcome Trust, said the findings through Andersen including his colleagues are "crucially important to bring an evidence-based view to the rumors that have been circulating about the origins on the virus (SARS-CoV-2) causing COVID-19."

"They conclude that the virus is the product on natural evolution," Goulding adds, "ending any speculation about deliberate genetic engineering."

Possible origins on the virus

Based on their genomic sequencing analysis, Andersen including his collaborators concluded that the most likely origins for SARS-CoV-2 followed single on two viable scenarios.

In single scenario, the virus evolved to its current pathogenic state through natural choosing inside a non-human proprietor including in those days jumped to humans. This is how previous coronavirus outbreaks have emerged, in the company of humans contracting the virus after direct exposure to civets (SARS) including camels (MERS). The researchers proposed bats while the most likely reservoir for SARS-CoV-2 while it is very alike to a stick coronavirus. There are no documented cases on direct bat-human transmission, however, suggesting that an intermediate proprietor was likely involved among bats including humans.

In this scenario, both on the distinctive features on SARS-CoV-2's spike protein -- the RBD portion that binds to cells including the cleavage site that opens the virus up -- would have evolved to their current state previous to entering humans. In this case, the current epidemic would probably have emerged quickly while soon while humans were infected, while the virus would have already evolved the features that make it pathogenic including able to spread among people.

In the other proposed scenario, a non-pathogenic version on the virus jumped from an animal proprietor into humans including in those days evolved to its current pathogenic state within the anthropoid population. For instance, some coronaviruses from pangolins, armadillo-like mammals found inside Asia including Africa, have an RBD structure very alike to that on SARS-CoV-2. A coronavirus from a pangolin could possibly have been transmitted to a human, either directly or through an intermediary proprietor such while civets or ferrets.

Then the other distinct spike protein characteristic on SARS-CoV-2, the cleavage site, could have evolved within a anthropoid host, possibly via restricted undetected circulation inside the anthropoid population previous to the beginning on the epidemic. The researchers found that the SARS-CoV-2 cleavage site, appears alike to the cleavage sites on strains on bird flu that has been shown to transmit easily among people. SARS-CoV-2 could have evolved such a virulent cleavage site inside anthropoid cells including soon kicked off the current epidemic, while the coronavirus would possibly have become far more fitted on spreading among people.

Study co-author Andrew Rambaut cautioned that it is difficult assuming not impossible to know at this point which on the scenarios is most likely. If the SARS-CoV-2 entered humans inside its current pathogenic form from an animal source, it raises the probability on future outbreaks, while the illness-causing strain on the virus could still be circulating inside the animal population including might once again jump into humans. The chances are lower on a non-pathogenic coronavirus entering the anthropoid population including in those days evolving properties alike to SARS-CoV-2.

Funding for the research was provided through the US National Institutes on Health, the Pew Charitable Trusts, the Wellcome Trust, the European Research Council, including an ARC Australian Laureate Fellowship.

 

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