COVID Convergence Mutations

"[I'm struck by the] amazing amount of convergent evolution we're seeing [with SARS-CoV-2]."

"There are these infamous mutations -- E484K, N501Y, and K417N -- which all three variants of concern are accumulating. That, added together, is very strong biology that this is the best version of this virus in the given moment."

Wendy Barclay, virologist, professor,Imperial College London

"If you wanted to sort of write a little textbook about viral evolution, it's happening right now."

"If it keeps happening over and over again, it must be providing some real growth advantage to this virus."

Dr.Francis Collins, geneticist, director, U.S. National Institutes of Health

"It's shown a very strong set of opening moves."

"We don't know what the end game is going to look like."

Vaughn Cooper, evolutionary biology specialist, University of Pittsburgh School of Medicine

National Institutes of Health Director Francis S. Collins holds a model of SARS-CoV-2, the novel coronavirus, as he testifies on Capitol Hill in Washington, D.C., U.S. Graeme Jennings/Pool via REUTERS/

 

Perhaps it's just too much to hope for at this junction that the novel coronavirus is mutating itself out of the realm of viral pathogenic superiority. It's as though a contestant for the worst-killer-virus-in-history is given just so many moves to improve its game, and it's making the wrong choices, and compounding them in an effort to become more deadly, whereas the process it's undergoing is beginning to mute its morbid effects on its human hosts.

Spike protein of SARS-CoV-2

The new variants that were detected in geographies far from one another, such as Brazil, South Africa and Britain mutated spontaneously within a short time-frame late last year, where all three share some similar mutations located in the vital 'spike' region of the virus, enabling it to enter and infect human cells. The E484k mutation, that some scientists familiarly named "EEk" for its capacity to evade natural immunity from previous COVID-19 infections while reducing protection offered by current vaccines, which is designed to target the spike protein, is included.

Similar mutations independent of one another have been appearing in various parts of the globe, indicating that the coronavirus is in the process of undergoing "convergent evolution", according to a number of scientists Reuters has interviewed. With expectations that the coronavirus will continue to mutate, immunologists and virologists now suspect that the coronavirus may be exhausting the fixed number of moves its evolutionary cycle allows.

If such is actually the case, the long-term impact for its survival remains to be seen, based on whether a limit exists on the number of possible mutations it can attain to, making it less dangerous. "It is plausible that this virus has a relatively limited number of antibody escape mutations it can make before it has played all of its cards, so to speak", explained Shane Crotty, a virologist at the La Jolla Institute for Immunology, San Diego.

That being the case, drugmakers could be enabled to remain current with the virus, developing booster vaccines meant to target current variants directly, even as governments struggle to control a pandemic that has succeeded in killing close to three million people globally. Experts have been mulling over the theory that the virus could be imbued with a limited number of mutations since early February, and it has gathered momentum since a paper was published showing the spontaneous appearance of seven variants in the United States alone, all appearing in the same region of the spike protein.

The very process of different species independently evolving like traits to improve survival odds represents the core of evolutionary biology. The current pandemic represents an evolutionary process scientists have been able to study in real time through the vast scope of its impact, with 127.3 million global infections. No pathogen in history has ever evolved within a comparable global scrutiny as has SARS=CoV-2.

This coronavirus in particular is not held by scientists to be particularly 'clever'. It is programmed by nature to replicate itself every time it infects people. Each copy the virus produces can be flawed in its exactness to the original. Some of these inexact copies may be one-time occurrences, while those that render a survival advantage to the coronavirus have a tendency to persist. And before compromising its fitness or changing so much it is no longer the same virus, leads some specialists to believe the virus may have a limited number of mutations available to it.

"I don't think it's going to reinvent itself with extra teeth", Ian Jones, a professor of virology at University of Reading in Britain, added. "If it had an unlimited number of tricks ... we would see an unlimited number of mutants, but we don't", observed Michael Nussenzweig, immunologist at Rockefeller University in New York. 

However, predicting how a virus will mutate is challenging. Should there be limits on how the coronavirus could evolve, matters would certainly be simplified for vaccine developers. As an example Novavax Inc. is in the process of adapting its vaccine specifically to target the South Africa variant which appeared to render current vaccines less effective, in laboratory tests. According to chief executive Stan Erck, the virus is capable of so much change only yet still binds to human hosts. The hope is that the vaccine would "cover the vast majority of strains that are circulating". 

Data-sharing platforms like the Global Initiative on Sharing Avian Flu Data is enabling researchers to track the variants through its huge trove of coronavirus genomes. Recently, scientists identified seven U.S. coronavirus variants with mutations occurring in the same location in a critical portion of the virus representing additional evidence of convergent evolution.

Experiments exposing the virus to antibodies in an effort to force it to mutate are being carried out by other teams of researchers. The same mutation in many cases appeared as a result, including the infamous E484K. Helping to raise cautious optimism that mutations appear to share many of the same traits, even as tracking changes in the virus must continue to choke off its ability to mutate by reducing transmission through vaccinations and other measures taken to limiting the virus's spread.

Scientists at Duke University sequenced positive coronavirus tests to identify which strains are circulating in the community, on Feb. 3.Credit...Pete Kiehart for The New York Times