How Covid-19 mutations are changing the pandemic

At the start of its existence, Covid-19 acquired a capacity that would prove to be decisive in its relationship with human beings. The virus has detected a seemingly small change in its genetic code. It was probably an unfortunate accident – a fragment of genetic information from another virus got confused with that of the coronavirus as they both infected a bat.

However, in this small piece of genome were the instructions that altered a key part of the virus – its spike protein. This important protein surrounds the outside of the coronavirus and is the part that attaches itself to the outside of cells, helping the rest of the virus sneak inside where it can replicate.

This change in the spike protein of Covid-19 meant that it could hijack an enzyme found in the human body called furin. This enzyme acts like a pair of molecular scissors, normally cutting open hormones and growth factors to activate them. But when the furin cuts off part of the Covid-19 spike protein, which is normally folded into a series of loops on the outside of the virus, it opens up like a hinge.

‘This exposes a new sequence in the spike protein,’ says Yohei Yamauchi, reader in viral cell biology at the University of Bristol, UK, who has studied how this change may have led to Covid-19 becoming more infectious in humans. “This is one of the changes that makes this virus really different from the previous coronaviruses that caused Sars and Mers.”

This new mutation meant that Covid-19 could suddenly latch onto an important molecule found scattered outside of human respiratory cells called Neuropilin 1. This molecule helps transport material inside cells and deeper into tissue. – the mutation was like handing over the keys to Covid-19 at a new door in our cells and meant that the virus could replicate in greater numbers in the human respiratory tract.

Although this mutation was only one mutation in the short life of Covid-19, it was found to be important. Some researchers believe this could be one of the key mutations that allowed the coronavirus to skip species and start causing rapidly spreading disease in humans. But almost as soon as he did that, he started to detect other mutations.