Why does coronavirus evolve faster than us?

By Murilo Bomfim

Viruses have more children in a day than we can have in a lifetime

*

The text below answers the question asked by Amlcar Chagas, from Bahia, 9 years old, for the series Children’s questions, answers from science.

Fighting the pandemic was not easy for about a year, when the Alpha variant of the new coronavirus showed up in the UK and complicated even more the situation. Since then, other variants have been identified, giving the feeling that, even with the vaccines, we are drying ice. What explains this so fast evolution?

Viruses are very simple beings, made only of a protein capsule and its genetic material (DNA, RNA or both). When they reproduce, genetic information is copied and these copies are subject to error, generating mutations. like a cordless phone: some information different from the original story can always be passed on.

the accumulation of these errors that form a variant. It’s not just biology, however, that explains why the new coronavirus evolves faster than humans. The question is also mathematical. Mutations that occur in reproduction can lead to evolutionary changes. If, as a species, we have generations every twenty or thirty new years, the virus replicates itself every ten or twenty minutes. With a more frequent reproduction, the chances of accumulating mutations are much greater.

Coming back to biology, there are virus-specific mechanisms that differentiate us from viruses. One of them is the repair system. When a human cell is copied, the organism is able to check for errors. If an error is detected, it is corrected which limits our mutations. This system, however, is subject to failures: in these cases, we can develop genetic diseases, for example.

The new coronavirus is also capable of making repairs, but its detections are much less than those of the accurate humans. Most viruses don’t even have this system (were this the case with coronaviruses, letters in the Greek alphabet would be missing to name variants). . They can be divided into two groups: somatic and germinative. Somatics make up most of the organism. They are, for example, in the eyes, in the liver, in the skin. They reproduce more frequently and can generate different mutations (ranging from imperceptible changes to the creation of tumors). But these mutations are not passed on to offspring. Heredity is the exclusive power of germ cells, ova and sperm. The body understands that mutations that occur in these cells are transmitted to offspring, so the germ repair system is especially rigid. In the universe of viruses, any mutation is inherited.

Being a virus, however, has its advantages. The identification of the Alpha variant came as a surprise to the scientific community that followed the mutations closely. We go for a stable genome and, suddenly, a variant with fifteen, twenty mutations appears, says geneticist Hugo Aguilaniu, director-president of the Serrapilheira Institute. He says that this is possible when the virus finds a reservoir, a place where it can replicate without being noticed.

There are two theories to explain this sudden appearance of the variants. One of them is reproduction in immunocompromised people, who can harbor the virus for months. In this period, mutations accumulate and the infected person may transmit a coronavirus slightly different from the one that infected them.

The other possibility that the new coronavirus has found a reservoir is not in humans, but in other animals. A suspicious species are minks, which are mass slaughtered in European countries for being infected by the pathogen. In this case, the virus quickly spreads through the group, mutates and can re-infect humans.

Even with so many variants, vaccinate populations without wiping ice. While we are building resistance against severe cases of Covid-, the trend is for the virus to become less aggressive to human health, perhaps being compared to any common cold. good for us, that we can finally get rid of the pandemic, and good for it, that it will be able to replicate itself without making headlines.

*

Murilo Bomfim journalist.

We know that children ask the best questions, and that science can have good answers for them. Every month, theChild’s Questions, Answers from Science series invites a scientist to answer one of these fundamental questions. Do you have a suggested question? See here how to collaborate.

Back to top button