US investigation into the origins of SARS-CoV-2

SCIENCE/ INTERNATIONAL

Topic:

• GS-3: Science (Biology); Security
• GS-2: Effect of policies and politics of developed and developing countries

US investigation into the origins of SARS-CoV-2

Context: On May 14, a group of 18 scientists, most of them from the U.S., published a letter in the journal Science, calling for further investigation to determine the origin of the COVID-19 pandemic.

This was necessary because the two theories on the origins — 

• The virus could have been accidentally released from a laboratory in Wuhan, China or 
• It was the result of a spillover from some animal species to humans 

Why understanding origin of virus is necessary?

Understanding the origin of the virus is important to both increase safety in laboratories undertaking biological research, and to prevent pandemics of animal origin.

What have U.S. intelligence agencies been asked to do?

• Since the call issued by scientists, U.S. President Joe Biden, on May 26, ordered an investigation by intelligence agencies into the origins of the virus. 
• The Director-General of the World Health Organisation (WHO) has also acknowledged that more work needs to be done on the lab leak theory, although a WHO team that visited Wuhan thought a leak to be the least likely hypothesis. 
• Department of Immunology and Microbiology at the Scripps Research Institute in the U.S. have hypothesised that the virus emerged from natural mutations.

Why has the demand for a fresh inquiry arisen?

• WHO’s governing forum, the World Health Assembly, mandated the Director-General in May 2020 to conduct an inquiry into the origin of SARS-CoV-2, and a joint probe was carried out by WHO and China in January-February 2021. 
• Since there was no conclusive evidence for either hypothesis — natural spillover or lab leak — there were apprehensions when the report leaned in favour of the animal origin hypothesis, describing it as “likely to very likely”, and stated that a laboratory incident was “extremely unlikely”.
• WHO Director-General said he did not see the investigation as being extensive enough, and went along with the view that requires further investigation, potentially with additional missions involving specialist experts, were necessary. 
• Some researchers from US have expresses concerns that the lab leak possibility had been given inadequate attention by the WHO team, and, in fact, treated as a “conspiracy theory”. 

What is the basis for the natural origin hypothesis?

• Based on its study of possible natural origins, the Joint WHO-China study report identifies a SARS-related coronavirus in a (horseshoe) bat (SARSr-CoV; RaTG13) to which the SARS-CoV-2 virus has 96.2% genomic similarity. 

• The novel coronavirus is less similar, by comparison, to the genome of viruses that have caused other epidemics such as SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). 

• Again, the higher infectivity of SARS-CoV-2 is attributed to peculiarities that it contains in the form of unique insertion of four amino acids in its spike protein that makes it more efficient than the virus causing SARS, for instance.

• Some coronaviruses found in pangolins in China are similar to SARS-CoV-2 in the RBD, showing that the optimised spike protein for efficient binding with human-like ACE2 may have resulted from natural selection. 

• It could be hypothesised that while no direct link could be identified to a progenitor virus for the one that has paralysed the world, the process by which the virus could adapt itself to spread among intermediate animals and then humans was a natural one.

• It is also possible that a progenitor virus was acquired by humans, and it became more efficient at transmission as it spread among humans during an undetected phase. 
• Scientists examined the possibility that there could have been an inadvertent release of SARS-CoV-2 from a laboratory, but argues that no progenitor virus with very high genetic similarity for such an experiment has been described, and the changes to the virus to transmit efficiently would have involved its repeated passage through cell cultures or animals with similar ACE2 receptors, which have not been described either.

Conclusion

What does stand out in the present crisis is the emerging call for a global framework for safe biological laboratory research, and more insight into related coronaviruses, animal hosts, mutations, and pathways by which novel viruses infect humans.