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

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

The analysis on public genome sequence data from SARS-CoV-2 including related viruses establish no grounds that the virus was made within a laboratory or or else engineered.

"By comparing the available genome sequence data appropriate to known coronavirus strains, we can firmly control that SARS-CoV-2 originated through normal processes," said Kristian Andersen, PhD, an associate professor on immunology including microbiology at Scripps Research including matching author on the paper.

In addition to Andersen, authors on the paper, "The proximal origin 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 origin illnesses ranging widely within severity. The first known critical illness caused via a coronavirus emerged with the 2003 Severe Acute Respiratory Syndrome (SARS) epidemic within China. A second outbreak on critical illness began within 2012 within Saudi Arabia with the Middle East Respiratory Syndrome (MERS).

On December 31 on last year, Chinese authorities alerted the World Health Organization on an outbreak on a novel strain on coronavirus causing critical illness, which was subsequently called SARS-CoV-2. As on February 20, 2020, nearly 167,500 COVID-19 cases own been documented, though many more mild cases own disposed gone undiagnosed. The virus has killed over 6,600 people.

Shortly following the epidemic began, Chinese scientists sequenced the genome on SARS-CoV-2 including made the data available to researchers worldwide. The resulting genomic sequence data has shown that Chinese authorities rapidly detected the epidemic including that the number on COVID-19 cases own been increasing because on anthropoid to anthropoid transmission following a single introduction into the anthropoid population. Andersen including collaborators at several other investigation institutions used this sequencing data to explore the origins including development on SARS-CoV-2 via focusing within on several tell-tale features on the virus.

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

Evidence appropriate to normal evolution

The scientists establish that the RBD portion on the SARS-CoV-2 stake proteins had evolved to effectively target a molecular feature on the outer on anthropoid cells called ACE2, a receptor involved within regulating blood pressure. The SARS-CoV-2 stake protein was so effective at binding the anthropoid cells, within fact, that the scientists concluded it was the result on normal selection including not the product on genetic engineering.

This grounds appropriate to normal development was supported via data on SARS-CoV-2's spinal column -- its total molecular structure. If someone were seeking to engineer a new coronavirus as a pathogen, they would own constructed it from the spinal column on a virus known to origin illness. But the scientists establish that the SARS-CoV-2 spinal column differed substantially from those on already known coronaviruses including mainly resembled related viruses establish within bats including pangolins.

"These two features on the virus, the mutations within the RBD portion on the stake protein including its distinct backbone, rules out laboratory manipulation as a potential origin appropriate to SARS-CoV-2" said Andersen.

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

"They conclude that the virus is the product on normal 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 the majority disposed origins appropriate to SARS-CoV-2 followed one on two feasible scenarios.

In one scenario, the virus evolved to its current pathogenic state through normal selection within a non-human proprietor including then jumped to humans. This is how previous coronavirus outbreaks own emerged, with humans contracting the virus following direct exposure to civets (SARS) including camels (MERS). The researchers proposed bats as the the majority disposed reservoir appropriate to SARS-CoV-2 as it is very similar to a bat coronavirus. There are no documented cases on direct bat-human transmission, however, suggesting that an intermediate master or mistress on ceremonies was disposed involved between bats including humans.

In this scenario, both on the special features on SARS-CoV-2's stake protein -- the RBD portion that binds to cells including the cleavage site that opens the virus up -- would own evolved to their current state prior to entering humans. In this case, the current epidemic would probably own emerged rapidly as soon as humans were infected, as the virus would own already evolved the features that make it pathogenic including able to extend between people.

In the other proposed scenario, a non-pathogenic version on the virus jumped from an animal host into humans including then evolved to its current pathogenic state within the anthropoid population. For instance, some coronaviruses from pangolins, armadillo-like mammals establish within Asia including Africa, own an RBD structure very similar to that on SARS-CoV-2. A coronavirus from a pangolin could possibly own been transmitted to a human, either directly or through an intermediary master or mistress on ceremonies such as civets or ferrets.

Then the other distinct stake protein characteristic on SARS-CoV-2, the cleavage site, could own evolved within a anthropoid host, possibly via limited undetected circulation within the anthropoid population prior to the beginning on the epidemic. The researchers establish that the SARS-CoV-2 cleavage site, appears similar to the cleavage sites on strains on bird flu that has been shown to transmit easily between people. SARS-CoV-2 could own evolved such a virulent cleavage site within anthropoid cells including soon kicked off the current epidemic, as the coronavirus would possibly own become far more capable on spreading between people.

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

Funding appropriate to the investigation was provided via 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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