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Most strains of the SARS-CoV-2 virus have a specific mutation that makes them transmissible faster, to the point that these strains are now dominant globally, new evidence suggests.
Contrary to the more strains in the early pandemic, currently 99.9% of the SARS-CoV-2 strains circulating in the study had the D614G mutation in the mutant protein. In addition, people infected with the D614G strain had a higher nasopharyngeal viral load when diagnosed.
That’s not all the bad news. This single point mutation was not related to clinical severity of COVID-19. Additionally, the mutation will not affect the effectiveness of any antibody cocktails, small molecule therapy, or vaccines in development.
What’s more, “as bad as SARS-CoV-2, we could have dodged a bullet about its variable rate,” said study author Ilya Finkelstein, PhD. Medscape Health News. For example, the virus mutates much more slowly than HIV, giving researchers a chance to stay one step ahead, he said.
The study was published online October 30 in the journal mBio.
The study was possible because colleagues at the Houston Methodology Hospital system sequenced the genomes of 5085 strains of SARS-CoV-2 early at an outbreak and during a second infection over the summer, Finkelstein said. .
The single data source also includes information from plasma, nursing plasma and patient results. Finkelstein, a researcher and director of the Finkelstein Laboratory at the University of Texas Austin, said studying large populations as diverse and as large as Houston helped create a “molecular fingerprint” for viruses and will continue to be very helpful.
D614G is the most common gene substitution found by researchers, occurring in 82% of SARS-CoV-2 strains during the first wave from March 5 to May 11. increased to 99.9% in the second wave, identified as May 12 to 7 July in the study.
The spike frequency “is very rapid, just a few months,” the researchers note.
The presence of the mutation during the first episode was independently related to the number of days of ventilation, the total length of hospital stay, and the length of time in hospital ICU. However, it is not associated with any significant difference in patient results.
The D614G mutation is so common around the world that these viruses are considered reference strains. Researchers believe that D614G is dominant because it increases the ability of the mutant protein to open cells for virus entry.
Despite the large number of virus strains assessed, the samples represented only about 10% of Houston COVID-19 cases during the study, a potential limitation. Additionally, some of the collected samples cannot be used for high-quality genome analysis because of the limited amount of viral nucleic acids.
In addition, it is still unclear whether immune interactions between the host and the virus play an important role. However, the researchers note in the paper that “available data suggest that overall, host genetics does not play a large role in determining outcome in the majority of adult patients, after when infected. “
Monitoring is going on
These findings will help us understand the origin, composition and trajectory of future infection waves as well as the potential impact of a host’s immune response, the researchers added. therapeutic actions for the evolution of SARS-CoV-2 ”.
In the future, continuous molecular monitoring of SARS-CoV-2 “may provide insights into the origins of new outbreaks and infections occurring when public health constraints are limited. copper was loosened further, schools and colleges reopened, vacations occurred, commercial air travel increased and individuals changed their behavior because of COVID-19 ‘fatigue’ , the researchers noted.
They added that the genomic data would also be helpful in evaluating the molecular evolution that is taking place in sping and other proteins “when fundamental herd immunity is created, by natural exposure. with SARS-CoV-2 or by vaccination. “
Additional authentication is guaranteed
“The study is very interesting and well done,” said Professor Noam Shomron, Ph.D., a fellow of the Faculty of Medicine at Tel Aviv University, Israel. Medscape medical news.
“Analysis of the evolution of the SARS-CoV-2 molecule in a particular region in the United States … can be seen as a microcosm of what happens in other major cities in the United States,” he said. .
However, “before reaching any conclusion, this needs further confirmation,” adds Shomron, the author of a study, adding that differences in genetic alleles may partly explain the difference between infection rates, severity and mortality related to SARS-CoV-2.
“We know that many other features and collaborators can influence the results – even social constraints can create bias in observations,” he said.
Finkelstein and Shomron did not disclose any related financial ties.
mBio. Published online October 30, 2020. Full text
Damian McNamara is an employee Journalist based in Miami. He covers a wide range of medical specialties, including infectious, digestive and rheumatic diseases. Follow Damian on Twitter: @MedReporter.