SARS-CoV-2 is natural: No proof of covi leakage from Wuhan and US research labs

Source : Scripps Research Institute
Ref :  https://www.scripps.edu//news-and-events/press-room/2020/20200317-andersen-covid-19-coronavirus.html
Image courtesy : Creative Commons / Wikimedia

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

The analysis of public genome sequence data from SARS-CoV-2 and related viruses found no evidence that the virus was made in a laboratory or otherwise engineered.

"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, PhD, an associate professor of immunology and microbiology at Scripps Research and corresponding author on the paper.

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

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

On December 31 of last year, Chinese authorities alerted the World Health Organization of an outbreak of a novel strain of coronavirus causing severe illness, which was subsequently named SARS-CoV-2. As of 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 of SARS-CoV-2 and made the data available to researchers worldwide. The resulting genomic sequence data has shown that Chinese authorities rapidly detected the epidemic and that the number of COVID-19 cases have been increasing because of human to human transmission after a single introduction into the human population. Andersen and collaborators at several other research institutions used this sequencing 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.

Evidence for natural evolution

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.

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

"These two features of the virus, the mutations in the RBD portion of the spike protein and its distinct backbone, rules out laboratory manipulation as a potential origin for SARS-CoV-2" said Andersen.

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

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

Possible origins of the virus

Based on their genomic sequencing analysis, Andersen and his collaborators concluded that the most likely origins for SARS-CoV-2 followed one of two possible scenarios.

In one scenario, the virus evolved to its current pathogenic state through natural selection in a non-human host and then jumped to humans. This is how previous coronavirus outbreaks have emerged, with humans contracting the virus after direct exposure to civets (SARS) and camels (MERS). The researchers proposed bats as the most likely reservoir for SARS-CoV-2 as it is very similar to a bat coronavirus. There are no documented cases of direct bat-human transmission, however, suggesting that an intermediate host was likely involved between bats and humans.

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

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

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

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

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

SARS-CoV-2 is natural: No proof of covi leakage from Wuhan and US research labs 

The above article published by Scripps Research Institute on 17 March 2020 not only suggests that the virus responsible for COVID-19 (covid, in short) is natural but also suggests that there is no evidence to prove virus SARS-CoV-2 (covi, in short) leakage from virus research laboratories in Wuhan and the US (Fort Detrick) since it is not human-engineered. In addition, two experts, Denis Shoham and Shi Zhengli, have denounced claims that the spread of covi is due to virus leakage from laboratories such as Wuhan and Fort Detrick.

Israeli Military Intelligence officer Denis Shoham of The Institute for Defence Studies and Analyses based in India told Factcheck.kz, the Kazakhstan branch of Factcheck Finder, that "there is no evidence or evidence of such as incident:, i.e. in the form of a virus leak in connection with the Chinese biological warfare development programme. 

Denis comments about the Wuhan virus outbreak, "The whole event might of course be completely natural and that is how it seems to be at the moment. More information is needed concerning the origination of the virus."

Shi Zhengli, the virologist of the Wuhan P4 Laboratory of the Wuhan Institute of Virology under the Chinese Academy of Sciences, have replied to China media Caixin.com recently that covi is a natural recombinant virus. She says a bat species in China is very likely to be the natural host of the virus and in order to transmit the virus to humans, an intermediate host must be investigated and identified using molecular science. Furthermore, she claims and swears that there is no virus leakage from the Wuhan P4 Laboratory. She adds that it is even impossible for the virus to originate from the US.

The covid virus originates from mainland China. It is mainland China's accountability to the world and responsibility to reveal its findings on its laboratory virus samples and wild animal samples taken from the already-closed Wuhan Huanan Seafood Market, that their virologists have studied, to the world so that external virologists can further investigate, identify and let the world know the actual natural host (which bat species if it is a bat?) and the intermediate host (is it a snake, a pangolin species, a ferret or other animal species?) that infects the 'patient zero' of covid, who must also still be investigated.

Web Refs : 
https://tfc-taiwan.org.tw/articles/2293;
https://factcheck.kz/health/manipulyaciya-izrailskij-ekspert-svyazal-koronavirus-s-biologicheskim-oruzhiem/;

Shi Zhengli : Unexpect SARS-like coronavirus cross-species infection will occur in Wuhan,
https://staygate.blogspot.com/2020/03/shi-zhengli-unexpect-that-sars-like.html

Russian Ministry of Health first to officially announce SARS-CoV-2 is recombinant virus,
https://staygate.blogspot.com/2020/02/russian-ministry-of-health-first-to.html