https://www.businessinsider.com/coronavirus-not-mutating-to-spread-genetics-show-2020-9
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Scientists have been regularly collecting and genetically sequencing samples of the virus to track how it's changing. Over time, that monitoring has revealed, one version became more prevalent than the rest: a strain with the mutation dubbed D614G.
According to a new, preliminary study from researchers at Houston Methodist Hospital, that mutated strain was responsible for nearly every COVID-19 infection there this summer, during in Texas' second peak of infections.
James Musser, the senior author of the new research, thinks that means the mutated strain which contains the amino acid glycine, or G is more transmissible than the original.
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Geneticists classify the original version of the coronavirus as the "D lineage," whereas strains with the D614G mutation are categorized as the "G lineage." The G lineage didn't crop up until January, Hodcroft said. Since then, according to her Nextstrain colleague Richard Neher, it has come to dominate "almost all places in the US, Europe, and Latin America."
The particular mutation that differentiates these strains is a swap at the amino acid labeled 614 the part of the virus' genome that codes for the shape of its spike protein.
That spike is what the coronavirus uses to invade our cells, so it's possible a tweak there could make it easier for the virus to infect our bodies. Indeed, a June study found that the D614G strain is three to six times better at infecting human cells in the lab than its predecessor. Other preliminary research has also suggested that the mutation enhances the virus's ability to invade cells.
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His research the largest genetic study of the virus to date in the US involved more than 5,000 virus samples from Houston collected between March and July. The team classified the samples collected between March 5 and May 11 as part of the city's "first wave" of infections. In that group, the data showed, 82% contained the D614G mutation. But in the set of samples collected between the end of that first wave and July 7, the figure jumped to 99.9%.
Musser said this shows the G variant "out-competes the D variant."
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Most mutations her team is seeing are harmless, Hodcroft added, and the coronavirus is mutating slowly. Hodcroft's project sees a maximum of 20 to 25 differences between sequences that contain about 30,000 genetic building blocks.
"People are getting the same virus now that we saw in the spring," she said.