Epidemics of Covid-19 and other diseases are on the rise every winter. The causes are well known: more people confined indoors, lower immune defenses … But there is also a reason linked to the very structure of the coronavirus, one of the proteins of which is sensitive to temperature.
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As you might expect, a fifth wave of Covid-19 is sweeping Europe at the end offall. There are well-known reasons for this greater diffusion from virus during winter : When it’s cold, we tend to spend most of our time indoors, resulting in greater transmission. L’air cold and dry also favors the entry of virus in the nose, and our immune defenses are also weakened by low temperatures. Several studies have also shown that the virus himself was sensitive to cold, spread more in wet weather (the virus stays longer in the air) and didn’t like the sun.
What is the relationship between coral and the coronavirus?
To all these reasons is now added another hypothesis linked to the molecular structure itself of Sars-CoV-2, which researchers have discovered … thanks to the coral. Small step back. In 2019, Chinese scientists have discovered than galectin, a glycoprotein involved in different biological processes, was involved in the recognition between symbiotic dinoflagellates and coral polyps, and that this process was sensitive to temperature variations. The bond between the two is thus made more easily between 25 ° C and 30 ° C. This recognition mechanism, on the other hand, works much less well above 30 ° C, which explains why the global warming drives the coral bleaching, which then becomes more susceptible to bacterial infections pathogens. And this is where we come to our coronavirus.
A protein that changes the structure of the virus depending on the temperature
Gustavo Caetano-Anollés, professor at the Institute of Biology genomics of the University of Illinois and colleagues, analyzed tens of thousands of genomes of Sars-CoV-2, they discovered a galectin-like structure on the spike protein, the one used by the virus to bind and enter the cell. ” These protein structures sense external conditions and, when not too hot or humid, trigger a spike protein structure change allowing theRNA viral to enter host cells », Describes the researcher, main author of the study published in Methods in Microbiology.
” Imagine the spike protein like a little jar that has flaps on the top to keep it closed. When the temperature is high, the jar remains completely closed and cannot spill its infectious contents. But, under cool, dry conditions, the jar opens, releasing a peptide of fusion which helps to fuse the virus and the membranes of the host cells. This allows the virus to enter the cell and do more damage », Illustrates Gustavo Caetano-Anollés.
No more dangerous mutations during winter
This discovery not only explains why the virus is more infectious in winter, but also implies that it tends to mutate more during this season. By observing the genomic changes of Sars-CoV-2 around the world, they found mutation surcharges in winter or in high altitude places where the weather stays cool all year round. Conversely, no major mutations have been observed in the low-lying tropics. It is also observed that the variants Delta and Omicron appeared in India and South Africa respectively in late or early winter. ” By studying more deeply the molecular modifications of the virus, we may be able to detect future mutations earlier and develop new vaccines. “, Hope the authors of the study.
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