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Rumor that human manipulation of SARS-CoV-2 has been refuted
There are many rumors surrounding the origin of the new SARS-CoV-2 coronavirus. A common suspicion is, for example, that the virus was man-made and either accidentally or deliberately released. A recent study now proves that the novel corona virus originated in a natural way.
Researchers at the Scripps Research Institute conducted a comprehensive analysis of the genome sequence data from SARS-CoV-2 and found no evidence that the virus was produced in a laboratory or otherwise manipulated. The results were recently presented in the renowned journal "Nature Medicine".
SARS-CoV-2 is a product of natural evolution
The novel SARS-CoV-2 coronavirus, which first appeared in the city of Wuhan in China last year and has since caused a global COVID-19 pandemic that has already affected over 150 countries, is the product of natural evolution, like one shows current analysis of the genome.
Study author: "SARS-CoV-2 was certainly created, of course."
"By comparing the available genome sequence data of known coronavirus strains, we can determine with certainty that SARS-CoV-2 was caused by natural processes," emphasizes Dr. Kristian Andersen, professor of immunology and microbiology at Scripps Research and corresponding author of the study.
How do the researchers come to this statement?
Shortly after the epidemic began, Chinese scientists sequenced the SARS-CoV-2 genome and made the data available to science. Andersen and other researchers from several institutions used this sequence data to decipher the origin and development of SARS-CoV-2 by focusing on several features of the virus.
Armed with grab hooks and can openers
Among other things, the researchers analyzed the genetic template for spike proteins, the fittings, so to speak, on the outside of the virus. The virus uses these proteins to hold onto and penetrate the outer walls of human and animal cells.
According to the researchers, there are two important characteristics. The so-called receptor binding domain (RBD) - a kind of gripping hook that clings to host cells, as well as the cleavage site - symbolically a molecular can opener that enables the virus to break open cells and penetrate into the host cells.
First proof of natural evolution
As part of their analysis, the researchers found that the RBD portion of the SARS-CoV-2 spike protein (“grappling hook”) had developed to effectively target a molecular trait on the outside of human cells. More specifically, it is the so-called ACE2 receptor that is involved in regulating blood pressure. The SARS-CoV-2 spike protein binds to human cells so effectively that, according to the researchers, it can only be the result of a natural selection. According to the current state of genetic engineering, it is not possible to artificially produce such a flawless product.
Second proof of natural origin
This evidence is supported by the analysis of the backbone of SARS-CoV-2, i.e. the entire molecular structure. “If someone wanted to develop a new corona virus as a pathogen, they would have constructed it from the backbone that is responsible for known diseases,” says the research team.
However, the molecular structure of SARS-CoV-2 differs significantly from known and dangerous coronaviruses and, according to the study, is most similar to pathogens that are found in bats and pangolins.
Manipulation rumors refuted
"These two features of the virus, the mutations in the RBD part of the spike protein and its pronounced backbone, rule out laboratory manipulation as a possible source of SARS-CoV-2," Andersen sums up.
Dr. Josie Golding, head of the epidemic department at the British Wellcome Trust, attributes the research findings to a critical importance, “to get an evidence-based view of the rumors circulating about the origin of the SARS-CoV-2 virus that causes COVID-19 . They come to the conclusion that the virus is the product of natural evolution, "emphasizes Goulding," and thus end any speculation about deliberate genetic manipulation. "
The most likely origins - two scenarios
Based on their analysis, the researchers suggest two possible origins. In one possible scenario, the virus developed to its current pathogenic state through natural selection in a non-human host and then spread to humans. In this way, previous coronavirus outbreaks had arisen, in which people became infected with the virus after direct exposure to civet cats (SARS) and camels (MERS).
Bats as the host of origin
The researchers consider bats to be the most likely reservoir of SARS-CoV-2 because it is very similar to a bat coronavirus. However, there are no documented cases of direct transmission of bats to humans, suggesting that an intermediate host was likely involved.
If this scenario applies, the characteristic features of the SARS-CoV-2 spike protein and the cleavage site have developed prior to human entry. This case suggests a rapid spread, since the virus would have already developed the features that make it pathogenic and would thus be able to spread quickly between people.
Scenario two: SARS-CoV-2 developed in humans
In the other proposed scenario, a non-pathogenic version of the virus jumped from an animal host to humans and then developed into its current pathogenic state in the human population.
Pangolin as the host of origin
For example, some coronaviruses from pangolins, armadillo-like mammals found in Asia and Africa, have an RBD structure that is very similar to that of SARS-CoV-2, according to the research team. A pangolin coronavirus may have been transmitted to humans, either directly or through an intermediate host, such as civet or ferret.
In this case, the cleavage site may have developed within a human host, possibly through limited, undetected circulation in the human population prior to the onset of the epidemic. The researchers found that the SARS-CoV-2 cleavage site is similar to the avian flu strain site, which has been shown to be easily transmitted between humans.
SARS-CoV-2 may have developed such a virulent cleavage site in human cells, triggering the current epidemic, as the cleavage site has made the coronavirus far more able to spread between humans.
Exact origin remains unclear
Co-author of the study, Andrew Rambaut, explains that at this point it is difficult, if not impossible, to know which of the scenarios is most likely. When the SARS-CoV-2, in its current pathogenic form, has entered humans from an animal, it increases the likelihood of future outbreaks, since the disease-causing strain of the virus still circulates in animal populations and could spread to humans again.
According to Rambaut, the probability that a non-pathogenic corona virus penetrates the human population and then develops properties similar to SARS-CoV-2 is lower, but also possible. (vb)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Graduate editor (FH) Volker Blasek
- Kristian G. Andersen, Andrew Rambaut, W. Ian Lipkin, et al .: The proximal origin of SARS-CoV-2; in: Nature Medicine, 2020, nature.com
- Scripss Reseach Institute: The COVID-19 coronavirus epidemic has a natural origin, scientists say (published: 03/17/2020), scripps.edu