The SARS-CoV-2 virus, which causes Covid-19, has the ability to momentarily accelerate its evolutionary pace, enabling variants to emerge more rapidly than other viruses, new research indicates.
The virus is undergoing short-lived mutational bursts and then returning to a slower base rate, according to a team led by Sebastian Duchene of the University of Melbourne and a research fellow at the Doherty Institute.
Duchene said all viruses usually mutate at a fairly constant rate, with most taking a year or more to develop a new variant.
“However, what we were seeing with the variants of SARS-CoV-2, particularly the variants of concern, is that they have undergone many more mutations than we would expect under the normal evolutionary pace of similar coronaviruses,” he said.
“The Delta variant, for example, emerged within just six weeks from its ancestral form.”
Duchene and his team conducted computational analyses of hundreds of genome sequences from SARS-CoV-2 strains to understand the mechanisms under which variants of concern emerge, with a focus on the first four: Alpha, Beta, Gamma and Delta.
“Initially it was believed that SARS-CoV-2 must have increased its evolutionary rate in general, but actually it’s the virus’ ability to temporarily increase its speed, which is causing the difference in pace,” he said.
“It’s like someone pumping the accelerator on a car.”
Duchene said these bursts could be driven by a number of factors, including prolonged infections in individuals, strong natural selection or increased transmissibility with unvaccinated populations, which allows the virus to rapidly spread and evolve.
The discovery highlights the importance of continued genome surveillance efforts to ensure early detection of new variants, he said.
“With this virus evolving so rapidly, early detection is paramount in enabling us to monitor and respond to the virus.”
He also stressed the need for increased vaccination. “Anything we can do to have less virus out there will help reduce the probability that new variants will emerge.”
The team of researchers at the Doherty Institute included Ash Porter, Wytamma Wirth and John Tay. Their research was published in the February edition of Molecular Biology and Evolution.
- George Russell
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