Coronavirus mutation may have made it more contagious

Nov. 5, 2020

A study involving more than 5,000 COVID-19 patients in Houston finds that the virus that causes the disease is accumulating genetic mutations, one of which may have made it more contagious. According to the paper published in the peer-reviewed journal mBIO, that mutation, called D614G, is located in the spike protein that pries open our cells for viral entry, according to a press release from The University of Texas at Austin.

Other study collaborators included researchers at Houston Methodist Hospital, Weill Cornell Medical College, the University of Chicago, and the U.S. Department of Energy’s (DOE) Argonne National Laboratory.

The paper shows “the virus is mutating due to a combination of neutral drift — which just means random genetic changes that don’t help or hurt the virus — and pressure from our immune systems,” said Ilya Finkelstein, Associate Professor of Molecular Biosciences at The University of Texas at Austin and co-author of the study.

During the initial wave of the pandemic, 71 percent of the novel coronaviruses identified in patients in Houston had this mutation. When the second wave of the outbreak hit Houston during the summer, this variant had leaped to 99.9 percent prevalence. This mirrors a trend observed around the world. A study published in July based on more than 28,000 genome sequences found that variants carrying the D614G mutation became the globally dominant form of SARS-CoV-2 in about a month. SARS-CoV-2 is the coronavirus that causes COVID-19.

The scientists noted a total of 285 mutations across thousands of infections, although most do not appear to have a significant effect on how severe the disease is. Ongoing studies are continuing to surveil the third wave of COVID-19 patients and to characterize how the virus is adapting to neutralizing antibodies that are produced by our immune systems. Each new infection is a roll of the dice, an additional chance to develop more dangerous mutations.

The UT Austin team tested different genetic variants of the virus’s spike protein, the part that allows it to infect host cells, to measure the protein’s stability and to see how well it binds to a receptor on host cells and to neutralizing antibodies. Earlier in the year, McLellan and his team at UT Austin, in collaboration with researchers at the National Institutes of Health, developed the first 3D map of the coronavirus spike protein for an innovation that now factors into several leading vaccine candidates’ designs.

The researchers found that SARS-CoV-2 was introduced to the Houston area many times, independently, from diverse geographic regions, with virus strains from Europe, Asia, South America and elsewhere in the United States. There was widespread community dissemination soon after COVID-19 cases were reported in Houston.

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