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Interviewer: Professor Emma Thomson, thank you very
much for taking the time to do this interview with us today
to discuss the phenomenon by which SARS-CoV-2 variants emerge,
and in particular to talk about which of these are the most worrisome, and why.
First of all, could you provide us with some background
to your recently published research in the journal
'Cell', addressing the range and breadth of SARS-CoV-2 mutations identified to date,
and in particular the study of the N439K mutation?
Prof. Thomson: Hello. Many thousands of mutations have now been
described in the SARS-CoV-2 genome since it first emerged at the end of 2019.
As in all viruses, these arise randomly as the virus replicates,
and as it passes from person to person, in the case of SARS-CoV-2 very rapidly, and right across the world.
Most of these mutations are of no consequence at all,
but when the virus comes under pressure, some of
these mutations (just through coincidence) may be beneficial to the virus.
Most RNA viruses replicate or divide inaccurately, but because this one,
SARS-CoV-2, has an exonuclease (a proofreading function) which is encoded by Nsp14,
this proofreads the virus as it replicates, and it makes the rate of change
quite slow compared to other viruses, like HIV or influenza.
The rate of new mutations was occurring at maybe around two changes per
month, until September or October 2020, when
suddenly we spotted what we now refer to as 'new variants' emerging, that had (for example)