TASS, October 26. Experiments on Syrian golden hamsters have shown that the most common of the new type of coronavirus mutations, D614G, makes it more infectious in the nasopharynx, trachea and upper respiratory tract. An article with the conclusions of scientists was published by a scientific journal Nature.
“In the nasopharynx and trachea of hamsters infected with the mutated form of SARS-CoV-2, we found an increased number of viral particles. However, this was not typical for their lungs. the virus can actually spread better from one victim to another, “the researchers write.
From the very beginning of the COVID-19 outbreak in China, scientists have been trying to understand in which direction and how the SARS-CoV-2 coronavirus that causes it is evolving. It is known to accumulate mutations in approximately at the same speed as the causative agent of the flu… However, scientists cannot yet fully understand what these mutations lead to.
First major change in coronavirus genome scientists fixed in the beginning of March. Then, new strains of coronavirus began to spread in Europe, which were characterized by a common mutation in the S gene, which controls the production of proteins in that part of the SARS-CoV-2 shell that is directly related to its penetration into the body.
Now this mutation – D614G – is present in almost all variations of the new type of coronavirus that circulate among the population of all continents of the Earth. Its rapid spread suggests that this mutation could make the coronavirus more infectious. 2.5 to 8 times.
Testing in practice
American molecular biologists led by a virologist from the University of Texas at Galveston (USA) Jessica Plant tested this hypothesis in experiments on Syrian hamsters (Mesocricetus auratus)… These animals are as susceptible to SARS-CoV-2 infection as humans and ferrets.
For experiments, scientists have created a new version of the coronavirus based on one of the very first strains that entered the United States back in January of this year and therefore has not yet acquired the D614G mutation. By inserting it into the genome of the strain, the scientists infected the hamsters with both versions of the virus. They then compared how the infection progressed in both cases.
It turned out that in the trachea and nasopharynx of rodents, the mutant version of the virus multiplied much more actively. This was clearly visible on the second day after the infection of the animals. Because of this, by the fourth or fifth day of illness, the number of viral particles in the upper respiratory tract of animals was several tens of times greater than that of hamsters from the control group.
Then biologists tested what would happen if you tried to infect animals with both versions of SARS-CoV-2 at the same time. It turned out that in the first week after infection, the number of viral particles with the D614G mutation in hamsters was 1.5 to 2.5 times higher.
Scientists do not yet know exactly how this mutation works. However, the experiments of Plant and her colleagues show that she can simultaneously make the virus more stable under adverse environmental conditions, and in a special way influence the interactions of antibodies and coronavirus particles, hiding the virus from the attention of the immune system.
On the other hand, these same experiments indicate that D614G did not make the coronavirus more dangerous for the lower respiratory tract and the rest of the lungs, nor did it increase its resistance to vaccines and drugs. Future SARS-CoV-2 mutations may not have such positive traits, so scientists should actively monitor new changes in its RNA and investigate their effect on the course of the infection, Plant and her colleagues conclude.