Chennai: A latest study has found that the SARS-CoV-2 virus, which causes Covid-19, is most ideally adapted to infect human cells, rather than bat or pangolin cells.
Researchers from Flinders University and La Trobe University in Australia used high-performance computer modelling of the form of the SARS-CoV-2 virus at the beginning of the pandemic to predict its ability to infect humans and 12 domestic and exotic animals.
Published in the journal Scientific Reports, the study was aimed to help identify any intermediate animal vector that may have played a role in transmitting a bat virus to humans.
The researchers used genomic data from the 12 animal species to painstakingly build computer models of the key ACE2 protein receptors for each species.
These models were then used to calculate the strength of binding of the SARS-CoV-2 spike protein to each species’ ACE2, which acts as the receptor for SARS-CoV-2 and allows it to infect the cell.
The results of the study showed that SARS-CoV-2 bound to ACE2 on humans cells more tightly than any of the tested animal species, including bats and pangolins.
The researchers explained that if one of the animals species tested was the origin, it would normally be expected to show the highest binding to the virus.
David Winkler, a professor at the La Trobe University, said, “Humans showed the strongest spike binding, consistent with the high susceptibility to the virus, but very surprising if an animal was the initial source of the infection in humans.”
“The computer modelling found the virus’s ability to bind to the bat ACE2 protein was poor relative to its ability to bind human cells,” Winkler said.
The researchers said this argues against the virus being transmitted directly from bats to humans.
According to Professor Nikolai Petrovsky from Flinders University, “If the virus has a natural source, it could only have come to humans via an intermediary species which has yet to be found.”
The team’s computer modeling shows the SARS-CoV-2 virus also bound relatively strongly to ACE2 from pangolins, a rare exotic ant-eater found in some parts of South-East Asia.
Winkler stated pangolins showed the highest spike binding energy of all the animals the study looked at, significantly higher than bats, monkeys and snakes.
The researchers said it was incorrectly suggested early in the pandemic by some scientists that they had found SARS-CoV-2 in pangolins.
“This was due to a misunderstanding and this claim was rapidly retracted as the pangolin coronavirus they described had less than 90 per cent genetic similarity to SARS-CoV-2 and hence could not be its ancestor,” Petrovsky added.