The U.S. government in 2009, launched a program to hunt for unknown viruses that can transfer from animals to humans and cause pandemics. The project — PREDICT was funded by the U.S. Agency for International Development, and it worked with teams in 31 countries, including China.
It was just one part of an emerging global network for infectious-disease surveillance. Despite the efforts of these disease detectives, the Coronavirus slipped past them. According to Scientific American, researchers were aware of the fact that coronaviruses, one of which caused severe acute respiratory syndrome (SARS), could be a recurring threat.
In 2007 researchers from the University of Hong Kong published a paper stating that the presence of many other SARS-CoV-like viruses in bats made this type of pathogen a “time bomb.” Scientists later expressed their fears over the similarities between the COVID virus and the one that caused the SARS-COV-2 in 2003.
According to the Wall street journal, RaTG13 is the name, rank and serial number of an individual horseshoe bat of the species Rhinolophus affinis, or rather of a sample of its feces collected in 2013 in a cave in Yunnan, China. Hazmat suit-clad scientists from the Institute of Virology, Wuhan collected these samples. Stored away and forgotten until January this year, the sample from the horseshoe bat contains the virus that causes COVID-19.
Where do pangolins come in the picture?
The role of pangolins in the spread of the COVID-19 is still ambiguous in nature. A study published by Maciej Boni at Penn State University and David Robertson at Glasgow University finds that human versions of the virus are more closely related to the RaTG13 horseshoe bat sample from the cave than they are to the known pangolin versions.
It is not yet possible to tell whether the virus went from bat to pangolin to people, or from bat to pangolin and bat to people in parallel. It could be a result of recombination but it is still unclear.
The study stated that a bunch of these culprit bats lived somewhere close to Wuhan or lead us to believe that this was a horrible coincidence that China’s Institute of Virology, a high-security laboratory where human cells were being experimentally infected with bat viruses, happens to be in Wuhan, the origin of today’s pandemic.
Why are Bat Viruses deadly?
A detailed study by the University of California, Berkeley suggested the fierce immune system response in bats to these viruses might be the prime reason they tend to multiply faster in bats. According to the Science daily, some bats — including those known to be the original source of human infections — have been shown to host immune systems that are perpetually primed to mount defences against viruses.
Viral infection in these bats leads to a swift response that walls the virus out of cells. While this may protect the bats from getting infected with high viral loads, it encourages these viruses to reproduce more quickly within a host before a defence can be mounted.
This suggests how bats can be a reservoir of numerous deadly viruses. The bats transmit the viruses to animals lacking a fast immune system and that is when it becomes fatal.
Genomic analysis and data
As per data mentioned in the World economic forum, the SARS-CoV-2 genome was rapidly sequenced by Chinese researchers. It is an RNA molecule of about 30,000 bases containing 15 genes, including the S gene which codes for a protein located on the surface of the viral envelope (for comparison, our genome is in the form of a double helix of DNA about 3 billion bases in size and contains about 30,000 genes).
A recent study under review suggested a more likely reservoir than bats. It further goes to prove that these genomic comparisons are in fact that the SARS-Cov-2 virus is the result of a recombination between two different viruses, one close to RaTG13 and the other closer to the pangolin virus.
A study by the American Society for Microbiology talks about a possible recombination mechanism that could have happened between two different animals. For recombination to occur, the two divergent viruses must have infected the same organism simultaneously.
With Inputs From – Matt Ridley, The Wall Street Journal