The Omicron variant of COVID is now thought to be highly transmissible but less virulent than some of its predecessors. This may be because it has ‘caught’ some genetic material from the virus that causes the common cold, say researchers in a new study.
While the study is still preliminary and the theory is yet to be proved, it is thought to be behind several documented features of Omicron that sets it apart from other COVID variants such as Beta and Delta. For one thing, it is far more contagious. For another, it has not proved virulent for now — the hospitalisation rate is low, and there are no recorded deaths till date.
Common infected cell
Researchers believe the Omicron — which is said to have 50 mutations — likely acquired at least one of its mutations by absorbing a snippet of genetic material from HCoV-229R, a cold virus. It is suspected to have done this while sharing an infected cell with the other virus.
Curious about the origin of #Omicron?
How could a “super mutant” SARS-CoV-2 have evolved?
“Omicron variant of SARS-CoV-2 harbors a unique insertion mutation of putative viral or human genomic origin” pic.twitter.com/ESMvp7yqE0
— nference (@_nference) December 3, 2021
This came to light when, while sequencing Omicron, researchers at US-based Nference, a data analytics firm that harnesses medical databases to create software, identified a snippet of genetic code from the cold virus. This has been documented in a pre-published research paper titled ‘Omicron variant of SARS-CoV-2 harbours a unique insertion mutation of putative viral or human genomic origin’, authored by AJ Venkatakrishnan, Praveen Anand, et al.
The researchers said this particular genetic sequence does not appear in any earlier version of the coronavirus. However, it is rather ubiquitous in less virulent viruses, such as those that cause the common cold. More interestingly, it is also seen in the human genome.
Omicron may have inserted the particular snippet into itself to make itself appear ‘more human’, said the researchers. This way, it would be better equipped to evade counterattacks by the human immune system, media reports quoted Venky Soundararajan, co-founder of Nference and a co-author of the research paper, as saying.
Such absorption of gene sequence would give the virus a better ability to transmit quickly; thankfully for humans, this would mean a mild or asymptomatic disease and fewer chances of death.
The human body offers a congenial environment for viruses to exchanges or transfer genetic sequences. Cells in the respiratory and gastrointestinal system are known to host SARS-CoV-2 and common cold coronaviruses simultaneously. When coinfection occurs, it often leads to viral recombination — wherein two viruses interact in the human cell and, while replicating themselves, generate new cells that contain genetic material from both the ‘parent’ virus cells.
The mutation may have first occurred when both the viruses interacted in the cells of a person infected with both COVID and common cold, say the researchers at Nference.