Early in its existence, Covid-19 acquired an ability that would prove decisive in its relationship with humans. The virus has noticed a seemingly minor change in its genetic code. It was likely an unfortunate accident – a fragment of genetic information from another virus became confused with that of the coronavirus while they both infected a bat.
However, this tiny piece of genome contained the instructions that altered an important part of the virus – its spike protein. This important protein inserts the outside of the coronavirus and is the part that attaches to the outside of cells, allowing the rest of the virus to sneak in where it can multiply.
This change in Covid-19’s spike protein meant it could hijack an enzyme in the human body called furin. This enzyme works like molecular scissors and normally snaps open hormones and growth factors to activate them. But when furin cuts off part of the Covid-19 spike protein, which is normally folded in a series of loops on the outside of the virus, it opens like a hinge.
“This exposes a new sequence in the spike protein,” said Yohei Yamauchi, a reader in viral cell biology at the University of Bristol, UK who has studied how this change may have caused Covid-19 to become more infectious in humans. . “It’s one of the changes that really makes this virus different from previous coronaviruses that caused Sars and Mers.”
This new mutation meant that Covid-19 could suddenly cling to an important molecule scattered around the outside of human respiratory cells called Neuropilin 1. This molecule helps transport material into cells and deeper into tissues – the mutation was as if you were Covid. -19 handed the keys to a new door to our cells and meant that the virus could replicate in greater numbers in the human airways.
Although this mutation was only one in Covid-19’s short existence, it turned out to be important. Some researchers think it is one of the main mutations that allowed the coronavirus to jump on species and start causing a rapidly spreading disease in humans. But almost as soon as it did this, it started incorporating other mutations.