Why have some scientists revived the laboratory leak theory of the zoonotic spillover?
The story so far: On May 14, a group of 18 scientists, most of them from the U.S., led by David A. Relman, published a letter in the journal Science, calling for further investigation to determine the origin of Covid-19 pandemic. Their reasoning is that despite many scientific advances in “understanding the causative agent, acute acute respiratory syndrome coronavirus 2 (SARS-CoV-2), its transmission, pathogenesis, and vaccine reduction, therapeutics, and non -drug interventions. ”, much work needs to be done.This is necessary because there are two theories of origin – the virus could have accidentally discharged from a laboratory or it is the result of a spillover from certain animal species to humans – both remain valid. the the novel coronavirus was first reported from Wuhan, a Chinese city that hosts a laboratory that conducts research on the virus, and the Program for Monitoring Emerging Diseases (ProMED) announced pneumonia of unknown cause in the city on December 30, 2019. Huanan in the city wet market associated with most of the earliest cases.
What are US intelligence agencies being asked to do?
Since the call issued by the scientists, US President Joe Biden, on May 26, ordered an investigation through intelligence agencies to the source of the virus. The Director-General of the World Health Organization (WHO), Tedros Adhanom Ghebreyesus, also acknowledged that much work needs to be done to teak the lab leak, even if a WHO team visited Wuhan thought a leak might be the least likely assumption. Kristian G. Andersen, a professor in the Department of Immunology and Microbiology at the Scripps Research Institute in the U.S., and his colleagues think the virus came from a natural mutation.
Why did the need arise for a fresh inquiry?
The WHO’s governing forum, the World Health Assembly, directed the Director-General in May 2020 to review the onset of SARS-CoV-2, and a joint review was conducted by WHO and China in January-February 2021. Since there is no conclusive evidence for any hypothesis – natural spillover or lab leak – there are fears if the report relies in favor of the assumption of animal origin, which is described as “likely to be probable”, and stated that a laboratory incident is “unlikely”.
Responding to the report, Dr. Tedros that he did not see the investigation as sufficiently adequate, and with the view that more study was needed. “Even if the group concludes that a laboratory leak is a less likely hypothesis, it requires further investigation, with more missions involving specialist leaks, which I am willing to disseminate,” he said. informed the WHO Member-States in a speech about the report in March of this year.
One of the researchers signed the letter Science, Marc Lipsitch, argued that laboratory origin, or natural origin, was not ruled out. No positive evidence was available from the interrogation. He was particularly concerned that the possibility of lab infiltration had received insufficient attention by the WHO team, and, in fact, was treated as a “conspiracy theory”. Understanding the origin of the virus is important to both increase the safety of laboratories conducting biological research, and to prevent pandemics of animal origin.
What is the basis of natural hypothesis?
Consistent with its study of possible natural origin, the Joint WHO-China study report identified a SARS-associated coronavirus in a (horse-drawn) bat (SARSr-CoV; RaTG13) in which the SARS-CoV-2 virus had 96.2% genomic similarity. The novel coronavirus is less similar, in comparison, to the genome of viruses that cause other epidemics such as SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Again, the higher prevalence of SARS-CoV-2 is attributed to the peculiarities inherent in the form of the unique incorporation of four amino acids into the spike protein that makes it more efficient than virus-induced. in SARS, for example.
Kristian G. Andersen, who writes about Proximal origin of SARS-CoV-2 with his companions in NATURE (March 17, 2020), concluded that natural selection of a human or similar human host appears to facilitate the optimal binding of the spike protein in the novel coronavirus with ACE2 receptors. “This is strong evidence that SARS-CoV-2 is not a product with intended manipulation,” the authors wrote.
Their arguments are based, among other things, on genetic differences between viruses: while RaTG13 in bats is more similar to SARS-CoV-2, the receptor binding domain (RBD) of the spike-the RBD protein binds to the ACE2 receptor – actually different for the two, the former showing to be less efficient. Again, some coronaviruses found in Chinese pangolins are similar to SARS-CoV-2 in RBD, showing that the optimized spike protein for efficient binding is similar to that of human ACE2. ‘g result from natural selection. It is conceivable that while no direct connection can be identified with a progenitor virus for a paralyzed one in the world, the process by which the virus can adapt itself to spread among animals with half and after the man is a natural.
It is also possible that a progenitor virus was acquired in humans, and it became more efficient to transmit because it spread among humans during an undetected stage. Reviewed by Dr. Andersen considered the possibility of unintentional release of SARS-CoV-2 from a laboratory, but argued that there was no single progenitor virus with a very high genius similarity for the same experiment described, and changes in virus transmission that would have been efficient would have involved frequent passage in cell cultures or animals with similar ACE2 receptors, which have also not been described.
What is surprising about the current crisis is the emerging call for a global framework for safe biological laboratory research, and a better understanding of associated coronaviruses, host animals, mutations, and pathway by which novel viruses attack humans.