Coronavirus: Sturdier spike protein may explain coronavirus variants' faster spread, study

This model shows the structure of the spike protein in its closed configuration, in its original D614 form (left) and its mutant form (G614). In the mutant spike protein, the 630 loop (in red) stabilizes the spike, preventing it from flipping open prematurely and rendering SARS-CoV-2 more infectious. (Credit: Bing Chen, PhD, Boston Children's Hospital)

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TORONTO -- Emerging coronavirus variants are able to spread faster than the original virus thanks to a studier spike protein, according to a new study.

Bing Chen, a professor of pediatrics at the Boston Children’s Hospital and his colleagues there analyzed changes to the spike proteins in the D614G mutation, which is carried by the fast-spreading coronavirus variants that originated in the U.K., South Africa, and Brazil.

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In order to do this, the researchers analyzed the spike protein using cryo-electron microscopy, a type of imaging used on cryogenically frozen specimensthat “has a resolution down to the atomic level,” according to the press release.

According to the team’s findings, published in the journal ‘Science’ on March 16, the original variant of the virus would bind to humans’ ACE2 receptors and then fold in on itself, fusing itself with their cells and getting inside, according to previous research by Chen.

With the original variant, the spike protein would sometimes collapse on itself too early, slowing the virus down, the release said.

The new variants with the D614G mutation have a more stable spike protein, however, and the issue of collapsing in on itself had been fixed, said a press release. The research also shows that the same mutation makes the spikes less binding with humans’ ACE receptors, but because of the sturdier spikes, it is more contagious.

"Say the original virus has 100 spikes," Chen said in the press release. "Because of the shape instability, you may have just 50 percent of them functional. In the G614 variants, you may have 90 percent that are functional, so even though they don't bind as well, the chances are greater that you will have infection."

Chen and his colleagues suggest that the current approved vaccines and any vaccines in the works should include the genetic code for this mutation.

“The more stable spike shape should make any vaccine based on the spike (as are the Moderna, Pfizer, and Johnson & Johnson vaccine) more likely to elicit protective neutralizing antibodies,” Chen was quoted as saying in the press release.