Ending speculations about deliberate genetic engineering ofnew coronavirus, scientists from the Scripps Research Institute, a non-profitresearch organization, have claimed that the COVID-19 pandemic is not from alab-created virus but has a natural origin.
The novel SARS-CoV-2 coronavirus that emerged in the city ofWuhan, China last year and has since caused a large scale COVID-19 epidemic isthe product of natural evolution.
The analysis of public genome sequence data from SARS-CoV-2and related viruses found no evidence that the virus was made in a laboratoryor otherwise engineered, according to findings published today in the journalNature Medicine.
"By comparing the available genome sequence data forknown coronavirus strains, we can firmly determine that SARS-CoV-2 originatedthrough natural processes," said Kristian Andersen, an associate professorof immunology and microbiology at Scripps Research and corresponding author onthe paper.
The first known severe illness caused by a coronavirusemerged with the 2003 Severe Acute Respiratory Syndrome (SARS) epidemic inChina. A second outbreak of severe illness began in 2012 in Saudi Arabia withthe Middle East Respiratory Syndrome (MERS).
On December 31 last year, Chinese authorities alerted theWorld Health Organization of an outbreak of a novel strain of coronaviruscausing severe illness, which was subsequently named SARS-CoV-2.
The coronavirus has now spread to more than 150 countries,infecting more than 184,000 and killing over 7,500 people.
Shortly after the epidemic began, Chinese scientistssequenced the genome of SARS-CoV-2 and made the data available to researchersworldwide.
The resulting genomic sequence data has shown that Chineseauthorities rapidly detected the epidemic and that the number of COVID-19 caseshave been increasing because of human to human transmission after a singleintroduction into the human population.
Andersen and collaborators at several other researchinstitutions used this sequencing data to explore the origins and evolution ofSARS-CoV-2 by focusing in on several tell-tale features of the virus.
The scientists analyzed the genetic template for spikeproteins, armatures on the outside of the virus that it uses to grab and penetratethe outer walls of human and animal cells.
This evidence for natural evolution was supported by data onSARS-CoV-2's backbone – its overall molecular structure.
If someone were seeking to engineer a new coronavirus as apathogen, they would have constructed it from the backbone of a virus known tocause illness.
But the scientists found that the SARS-CoV-2 backbonediffered substantially from those of already known coronaviruses and mostlyresembled related viruses found in bats and pangolins.
Josie Golding, PhD, epidemics lead at UK-based WellcomeTrust, said the findings by Andersen and his colleagues are "cruciallyimportant to bring an evidence-based view to the rumors that have beencirculating about the origins of the virus (SARS-CoV-2) causing COVID-19."
"They conclude that the virus is the product of naturalevolution," Goulding said.
Based on their genomic sequencing analysis, Andersen and hiscollaborators concluded that the most likely origins for SARS-CoV-2 followedone of two possible scenarios.
In one scenario, the virus evolved to its current pathogenicstate 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) andcamels (MERS).
The researchers proposed bats as the most likely reservoirfor SARS-CoV-2 as it is very similar to a bat coronavirus.
"There are no documented cases of direct bat-humantransmission, however, suggesting that an intermediate host was likely involvedbetween bats and humans," the authors noted.
In this case, the current pandemic would probably haveemerged rapidly as soon as humans were infected, as the virus would havealready evolved the features that make it pathogenic and able to spread betweenpeople.
In the other proposed scenario, a non-pathogenic version ofthe virus jumped from an animal host into humans and then evolved to itscurrent pathogenic state within the human population.
If the SARS-CoV-2 entered humans in its current pathogenicform from an animal source, it raises the probability of future outbreaks, asthe illness-causing strain of the virus could still be circulating in theanimal population and might once again jump into humans.