The latest chapter of the COVID-19 pandemic has been defined by vaccines and variants, the lineages of SARS-CoV-2 that have undergone notable mutations and taken root in different parts of the world. The most infamous examples of this line-up are the UK variant (aka the Kent variant), the South African variant, and the Brazilian variant – but the US has got more than its fair share of worrying variants too.
New preliminary research has reported that seven lineages of SARS-CoV-2 are on the rise across the US. Curiously, the seven variants have all independently gained similar mutations to the spike protein of the surface of the virus.
The new study, which is yet to be peer-reviewed, was posted on the preprint server medRxiv.
The report explains that seven independent lineages of SARS-CoV-2 with S:Q677H or S:Q677P mutations arose between August and November 2020. While it’s not certain whether the new variants in the US are innately more contagious, they are certainly on the rise in the southcentral and southwest US. Infections with SARS-Cov-2 viruses carrying a mutation called Q677P were first detected on October 23, 2020. Between December 1, 2020, and January 19, 2021, it represented almost 28 percent of cases detected in Louisiana and over 11 percent of cases in New Mexico.
All of these variants obtaining similar mutations might sound like an unlikely coincidence, but researchers do have some clear ideas about why this might be the case.
“The simplest explanation is that the mutations we are seeing at this site – Spike position 677 – might be one of the many subtle ways that this virus is fine-tuning itself to infect human cells,” Jeremy Kamil, co-author of the paper and a virologist at Louisiana State University Health Sciences Center Shreveport, told IFLScience.
“However, we have no evidence yet as to whether these changes make the virus any more transmissible or dangerous. Indeed, it has been plenty dangerous all along. One might conjecture that they could —potentially— give the virus some sort of slight advantage over one of its siblings that doesn’t have the change. I will stress that [if] there are any effects of these mutations, we expect they would prove to be quite small, and quite subtle,” Dr Kamil added.
Mutations are a natural part of the virus life cycle and, over the course of the pandemic, there have been thousands of SARS-CoV-2 variants that have undergone subtle mutations – most of which are inconsequential or harmless. However, if those mutations somehow provide the virus with an advantage over others, then they provide the opportunity to thrive. If they are all obtaining the same or similar mutations, then that could be a sign the mutation is beneficial for whatever selective pressures they are facing.
As Dr Kamil indicates, this instance is an example of convergent evolution, the process whereby different organisms independently evolve similar traits as a result of having to adapt to similar conditions. This is the reason why bats, bugs, and birds all have wings; they evolved them separately, as they provided the animals with an evolutionary advantage over others. It's also the reason why so many crustaceans have independently evolved into a crab-like form.
It’s something that’s also been seen in other parts of the world with other variants of SARS-CoV-2. For example, there were some reports of the UK variant mutating further and obtaining changes to the spike protein mutation found in the Brazilian and South African variants, known as E484K. Once again, scientists speculated that the mutation was giving the virus some kind of evolutionary advantage.