The origin of Covid 19 pandemic is still an unsolved question and a new discovery by Australian scientists has added to the doubts. The Australian scientists claim that SARS-CoV-2 virus that caused Covid 19 is most ideally adapted to infect human cells rather than bat or pangolin.
The scientists from Flinders University and La Trobe University used high-performance computer modelling of the form of SARS-CoV-2 virus at the beginning of the pandemic to predict its ability to infect humans and a range of 12 domestic and exotic animals. The study was to identify intermediate animal vector that could have played a role in transmitting a bat virus to humans.
They also looked at any risk posed by the susceptibilities of cats, dogs, cows, sheep, pigs and horses. They used genomic data from 12 animal species to build computer models of the key ACE2 protein receptors for each species.
MORE BOUND TO HUMAN CELLS
In the analysis, the scientists found that SARS-CoV-2 bound to ACE2 on human cells more tightly than in the animals, including bats and pangolins. Confirming this, La Trobe University Professor David Winkler said that human beings showed the strongest spike binding, which was consistent with the high susceptibility to the virus.
Flinders affiliated Professor Nikolai Petrovsky opined that the computer modelling found the virus’s ability to bind to the bat ACE2 protein was poor relative to its ability to bind to human cells. The professor thus argued that the chance of Covid 19 virus from bat to humans was rare. “And if the virus has a natural source, it could only have come to humans through intermediary species which has yet to be found,” Petrovsky said.
The computer modelling also showed the virus was bound strongly to ACE2 from pangolins, which are a rare exotic anteater found in some parts of South East Asia. Professor Winkler notes that pangolins showed the highest spike binding of all the animals the study looked at.
Professor Petrovsky says that Pangolin and SARS-CoV-2 spike proteins may have evolved similarities through a process of convergent evolution, genetic recombination between viruses, or through genetic engineering, with no current way to distinguish between these possibilities. “Overall, putting aside the intriguing pangolin ACE2 results, our study showed that the COVID-19 virus was very well adapted to infect humans,” says Professor Petrovsky.