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Interviewer: Professor Ralph Baric, thank you very much for taking
the time to do this interview with us today to further
update us on the recent findings regarding
the epidemiology of the ongoing SARS-2 COVID-19 pandemic.
We last discussed the evolution of this pandemic back in April of last year and today, the main point of concern is not so much the virus' infection rate,
which we are controlling more or less by imposing citywide lock-downs,
but rather the emergence of new variants.
What are some of the most concerning variants
discovered over the past couple of months and
what phenotypic advantages have been granted by these variants' mutations?
Prof. Barric: Well, new variants have new biological properties,
and those biological properties can change the epidemiology of the expanding pandemic.
For example, the first emerging variant that was really
well-described and characterized was called D614G,
which is a fancy name for a virus that emerged most likely in Southern Europe.
It had a mutation in
the spike glycoprotein and it rapidly became the dominant strain globally.
So the question is why?
The research that has come out regarding this virus
indicates pretty clearly that it is more infectious.
It can replicate better in cells from the nasal epithelium from humans,
and in transmission models in hamsters,
it can transmit more efficiently from a donor hamster
to a recipient hamster with an airspace in between them,
so it's airborne spread.
It's also in head-to-head,
what are called competition studies,
where you infect cells with equal amounts of the ancestral virus and the new variant.