A single molecular change in the lab enabled a coronavirus called Neocov to “efficiently infect” human cells using the same pathway that the SARS-CoV-2 uses to infect human cells, researchers from Wuhan University, Wuhan, China said in a report that is yet to be peer-reviewed.
Neocov has so far only been seen in bats and no instances have been reported in people but being closely related to the Middle Eastern Respiratory Syndrome (MERS) coronaviruses - traditionally more lethal but less transmissible than Sarscov2 - the study has raised concern that this too may lethally proliferate in people. Experts however say that such fears are unwarranted.
In their study, which is available on the online pre-print server bioRxiv.org, the scientists set out to find out they ways in which Neocov, a coronavirus known to be 85% similar to MERS coronaviruses, infected animal cells. MERS has a mortality rate of around 35%, far more than the coroanviruses.
The Sarscov2, for instance, spreads the way it does because it has figured out a way to use the enzyme called human angiotensin convertor 2 (hACE2) to infect cells. The scientists reported that they have, for the first time, shown Necov too uses bat ACE2. However this ACE2 is specific to the sub-species of bat and when the scientists checked if the Neocov could use hACE2, it turned out to be a “less favourable” mode of entry.
A single molecular barrier, close to where the virus bound to cells, “restricted” the human ACE2 from aiding a NeoCoV infection. However, when a mutation was artificially introduced, it made the NeoCoV 15-30 times more efficient at infecting human ACE2. Moreover, they underline, the infection could not be supressed by antibodies targeting SARS-CoV-2 or MERS-CoV.
“Considering the extensive mutations in the RBD regions (receptor binding domain or the part of the coronavirus latches on to human cells) of the SARS-CoV-2 variants, especially the heavily mutated Omicron variant, these viruses may hold a latent potential to infect humans through further adaptation via antigenic drift. It is also very likely that their relatives with human emergence potential are circulating somewhere in nature,” the scientists note.
Though the last two years have shown that variants of the coronavirus continually emerge and one cannot assume that evolution will make them progressively less harmful, scientists who’ve read the paper say this wasn’t cause for alarm. For one, spillover events - that is viruses endemic to one species jumping into another - continued to be rare, notwithstanding Sarscov2. Amidst suspicions that Sarscov2 was the result of a lab-leak, the official consensus continues to be that sarscov2 was a spillover into humans from an as-yet-unindentified species.
Vinod Scaria, Prinicipal Scientist, CSIR-Institute of Genomics and Integrative Biology told The Hindu that an artificially created mutation in the lab didn’t imply the same could easily occur in natural settings.
Physician and former president, Indian Medical Association, Rajeev Jayadevan in a Twitter thread said that Neocov was discovered in 2013-14 and “nothing has happened.” Despite similarities, the ACE2 receptors of bats and people were different and the odds of a sudden jump were low.
One expert however reckoned that because the mutation was engineered in a lab, it potentially meant that such viruses could be intentionally created. “What we’ve learnt from sarscov2 is that gain of function research is happening in laboratories and you don’t need expensive, complicated equipment to make infectious viruses. That’s the reality we have to acknowledge.” The person declined to be identified.