Guest essay by Eric Worrall
Scientist analysing a variant strain of Covid prevalent in New York and Italy have claimed that the mutation they identified likely makes the NY and Italian virus more contagious.
The researchers are not claiming the new variant is more deadly, but the increased ease with which the New York strain appears to spread might explain part of the reason why New York has had such a hard time containing their outbreak.
Mutated coronavirus shows significant boost in infectivity
COVID-19-causing viral variant taking over in the United States and Europe now carries more functional, cell-binding spikes.
June 12, 2020
JUPITER, FL — A tiny genetic mutation in the SARS coronavirus 2 variant circulating throughout Europe and the United States significantly increases the virus’ ability to infect cells, lab experiments performed at Scripps Research show.
There has been much debate about why COVID-19 outbreaks in Italy and New York have so quickly overwhelmed health systems, while early outbreaks in places like San Francisco and Washington state proved more readily managed, at least initially. Was it something about those communities and their response, or had the virus somehow changed?
Choe and Farzan have studied coronaviruses for nearly 20 years, since the first outbreak of SARS, a similar virus. They were the first to discover in 2003 that SARS bound to the ACE2 receptor on cells. Others’ experiments have shown the SARS-CoV-2 virus binds the same ACE2 receptor.
But Farzan and Choe note a key structural difference between spike proteins on the first SARS virus and this new pandemic strain. With both, under an electron microscope, the spike has tripod shape, with its three segments bound together at a backbone-like scaffold. But SARS-CoV-2 is different. Its tripod is divided in two discreet segments, S1 and S2.
Initially, this unusual feature produced unstable spikes, Farzan says. Only about a quarter of the hundreds of spikes on each SARS-CoV-2 virus maintain the structure they need to successfully infect a target cell. With the mutation, the tripod breaks much less frequently, meaning more of its spikes are fully functional, he says.
It is still unknown whether this small mutation affects the severity of symptoms of infected people, or increases mortality, the scientists say. While ICU data from New York and elsewhere reports a preponderance of the new D614G variant, much more data, ideally under controlled studies, are needed, Choe says.
…Read more: https://www.scripps.edu/news-and-events/press-room/2020/20200612-choe-farzan-coronavirus-spike-mutation.html
The study (currently undergoing peer review) is available here.
The variant strain has been active in New York for a while, so this discovery does not represent a deterioration in the current situation.