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Most SARS-CoV-2 virus strains are characterized by specific mutations that make them more contagious, and new evidence shows that these strains are currently predominant worldwide.
In contrast to the earlier and more diverse strains of the pandemic, 99.9% of the SARS-CoV-2 strains currently circulating in the study are characterized by a D614G mutation in the spike protein. In addition, people infected with the D614G strain have higher viral load in the nasopharynx at diagnosis.
That’s not all bad news. This single point mutation was not associated with worse clinical COVID-19 severity. Also, mutations are not expected to interfere with the efficacy of antibody cocktails, small molecule therapies, or vaccines under development.
Dr. Ilya Finkelstein
“It’s as bad as SARS-CoV-2, but it may have evaded the bullet in terms of the speed of mutation,” said research author Dr. Ilya Finkelstein. Medscape Medical News. This virus mutates much slower than HIVFor example, he said, giving researchers a chance to stay one step ahead.
Research Published online October 30th of the journal mBio.
Molecular detective
A colleague at the Houston Methodist Hospital system sequenced the genome of 5085 SARS-CoV-2 strains during the early stages of outbreak and during the second wave of summer infection, enabling the study, Finkelstein said. ..
Proprietary data sources also include information from plasma, convalescent plasma, and patient outcomes. Finkelstein, researcher and director of the Finkelstein Institute at the University of Texas at Austin, said studying large and diverse populations in metropolitan areas like Houston creates a “molecular fingerprint” of the virus. Helps you to.
D614G is the most common gene substitution discovered by researchers and appeared in 82% of SARS-CoV-2 strains in the first wave from March 5 to May 11. The rate of this mutation jumped to 99.9% in the second wave, defined as May. From July 12th to 7th in the study.
The surge in mutation frequency “occurred very rapidly in just a few months,” the researchers point out.
The presence of mutations during the first wave was independently associated Mechanical ventilation Days, overall length of stay, and length of stay in the ICU. However, it was not associated with a significant difference in patient outcomes.
These viruses are considered reference strains because the D614G mutation is now very common worldwide. Researchers believe that D614G dominates because it enhances the ability of the spike protein to open cells for the virus to invade.
Despite the large number of virus strains evaluated, the sample is only about 10% of the COVID-19 cases in Houston under study, with potential limitations. In addition, some of the samples collected could not be used for high-quality genomic analysis due to the limited viral nucleic acids.
Also, it remains unclear whether the host virus’s immune interactions play an important role. However, in the paper, the researchers said, “Available data play an overwhelming role in host genetics as a whole in determining the outcome of the majority of adult patients once a viral infection is established. It suggests that it will not work. “
Continuous monitoring
“The findings help us understand the origin, composition, orbit of future infectious waves, and the potential impact of host immune responses and treatments on the evolution of SARS-CoV-2,” the researchers say. I’m adding.
Going forward, SARS-CoV-2’s ongoing molecular surveillance will be “new as public health constraints are further relaxed, schools and universities reopen, holidays occur, and commercial air travel occurs. It may provide important insights into the origin of infection spikes and waves. Due to the “malaise” of COVID-19, individuals increase and change their behavior, “the researchers say.
They assess the ongoing molecular evolution of spikes and other proteins, because genomic data “because either natural exposure to SARS-CoV-2 or vaccination produces baseline herd immunity.” He added that it is also useful for.
Further verification is guaranteed
“This study is very interesting and well done,” said Dr. Noam Shomron, a member of the Tel Aviv University School of Medicine in Israel. Medscape Medical News..
“The SARS-CoV-2 molecular evolution in certain parts of the United States can be seen as a microcosm of what is happening in other big cities in the United States,” he said.
However, “We need to examine this further before jumping to the conclusion.” Studies that suggest differences Genetic allelic changes may partially explain the intercountry variation in infection rate, severity, and mortality associated with SARS-CoV-2.
“We know that many other features and contributors can affect outcomes. Even social constraints can create a bias in observation,” he said. ..
Finkelstein and Shomron do not disclose the relevant financial relationship.
mBio. Published online on October 30, 2020. Full text
Damian McNamara It is a staff A journalist based in Miami. He covers a wide range of medical disciplines, including infectious diseases, gastroenterology and rheumatology. Follow Damian on Twitter: @MedReporter..
