We are mutated, but we are getting stronger
Russian biologists told why mutations do not destroy viruses
Viruses are extremely difficult to destroy with drugs or radiation due to their main drawback – inaccurate copying of their own gene material, biologists say in an article published in the journal Microbiology and Molecular Biology Reviews (Agola, Gmyla, Emergency Services of Viral RNAs: Repair and Remodeling).
"The genomes of many RNA viruses contain a huge number of mutations due to the lack of reliable mechanisms for correcting such "typos". Despite this, almost all of them remain stable and almost do not change in stable environmental conditions. For example, the polio virus stored in our laboratory is, on average, almost identical in RNA structure to those strains of this pathogen that have been circulating for 30 years among people in other countries," the scientists write.
The first viruses, as evolutionists believe today, appeared on earth several billion years ago, almost simultaneously with the appearance of the first microbes on which they initially parasitized. Their traces, as geneticists have recently found out, are present in the DNA of almost every multicellular animal on Earth.
In addition to the mystery of the appearance of viruses, scientists have long been arguing and puzzling over how they manage to survive without actually having any genome repair systems and correcting small and large mutations in their own genetic code. This is especially true of RNA viruses, whose copies are collected by the enzyme RNA polymerase, which does not have error correction mechanisms and constantly introduces new "typos".
Vadim Agol and Anatoly Gmyl, biologists from Lomonosov Moscow State University, tried to find out why this lack of RNA viruses has not yet destroyed them or forced them to "invent" a new version of a protein that would not generate so many mutations when assembling new viral particles.
To answer this question, Gmyl and Agol analyzed several dozen scientific papers on the evolution of the so-called picornaviruses. They are among the most primitive and dangerous viruses, which include pathogens of polio, colds, hepatitis, encephalitis and many other diseases.
This comparison helped them discover several patterns related to the work of RNA polymerase and natural selection, which help the entire population of pathogens to survive, and not just individual "subspecies" of viruses.
As scientists have discovered, the inaccurate work of the enzyme prevents harmful mutations from spreading through the virus population. Even if their carrier penetrates into the cell and begins to multiply, its descendants will not always be carriers of such a "typo" in DNA due to the fact that the same section of RNA can be repeatedly changed.
Then natural selection comes into play, thanks to which the number of carriers of harmful mutations will decrease to a minimum, but not zero. This is important because a large genetic diversity helps viruses adapt to changes in the work of infected cells or allows them to switch to a new type of victim or protects them from drugs and antibodies.
All this, according to scientists, explains why RNA viruses quickly accumulate a large number of mutations, but do not die from them and remain similar to their counterparts from different parts of the Earth.
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