How Viruses Evolve: The Race is On

08 June, 2020
The coronavirus is spreading and, with it, so does the fear of mutation and that it may become even more lethal. But do we really know what a viral mutation is and what it involves?

Viruses and their influence on our lives are, unfortunately, more prominent in our society than ever before. Viral load, percentages, infected, and re-infected are terms that many of us have never thought about until this pandemic started. Yet there are even more complex mechanisms underlying current events. How viruses evolve is a very interesting subject and, in this article, we want to explain it to you.

How viruses evolve

Viruses have very short generational cycles. They enter the cell, take over its genetic information replication mechanism, replicate themselves and then the copies leave the cell to continue infecting.

Because of this speed and genetic plasticity, many viruses – especially RNA-type viruses – have exceptionally high mutation rates. This mutation rate, combined with the process of natural selection, allows viruses to adapt quickly and effectively to their hosts’ defense mechanisms.

This knowledge is essential to understand the pandemic we are currently experiencing. After all, what is a coronavirus if not an adaptation of a virus that was already present in animals?

If you want to know more about how viruses evolve, then read on.

Coronavirus specimens.

How viruses evolve: Change ensures success

Let’s start with a subject we already know about: the flu. The Influenza A and Influenza B viruses are equally prevalent in humans. Even so, Influenza A’s evolution is three times faster than Influenza B’s.

So, what’s the reason behind this curious fact?

A study published in the Journal of Virology has attempted to give us the answer to this question. Apart from the reaction of the immune system itself, mutations at a molecular level can play an important role in how the virus adapts. It may sound obvious, but it’s isn’t as easy to directly assume that a higher rate of evolution is due to a higher number of mutations. Many mutations can be unfavorable or inappropriate for the virus.

What happens if, due to a new mutation, it actually kills the host more quickly? In that case, the virus wouldn’t be able to propagate itself sustainably.

There is a very complex set of changes involved here. What may well happen is that the most effective changes may end up being fixed by natural selection. If a mutant virus keeps the host alive longer and can reproduce more and infect more people, then that’s the one that will reach more people.

We have to be clear about one thing: viruses don’t mutate to become better. These changes occur randomly and the most valid ones end up spreading. Following the example of the coronavirus that caused COVID-19, just think of how many mutant strains will have failed until the strain capable of infecting humans arrived on the scene!

You may also be interested in: What’s the Best Disinfectant for Viral Infections?

Coronavirus in the air.

Types of virus mutations

Overall, we can distinguish two types of general viral mutations:

  • Antigenic change: In this case, two or more viruses intermingle to give rise to a new one. This greatly misleads the immune system. It can get to know them and fight them separately, but their union is something it has never faced before, and, therefore, requires it to develop new mechanisms. One example here is the infamous influenza A.
  • Antigenic drift: This is a mutation in the proteins on the surface of the virus, which are the ones that the immune system normally recognizes and attacks. This occurs spontaneously and makes it difficult for the immune system to defend itself by using antibodies that it created in previous infections. This is why the flu vaccine has to change each year.

Our body needs to learn how to fight diseases, and vaccines are the most effective means. If a virus changes, then the vaccine will have to change with it. In this way, it can teach our body how to fight the virus without becoming infected.

Find out more: A Study Confirms Three Types of Coronavirus in the World

Mutation and the coronavirus

How do you apply all this knowledge to the current situation?

Currently, being able to know the mutation rate of the COVID-19 virus in such a short period is impossible. The existence of two different strains has been speculated. However, due to low sample groups, statistical biases, and different opinions, this idea seems to have lost popularity over time.

As experts in the field state in this excerpt from the Journal of Microbiology, mutation rates during a pandemic shouldn’t concern us. As we’ve already mentioned, many mutations are actually a bad thing for the virus. For substantial changes in severity or transmission to occur, then several genes have to vary together.

It’s very unusual for a virus to mutate so much that its processes and dynamics change in such a short time.

Again, the key is to remain calm. Variations and mutations in the natural world are extremely common. Scientists are continuing to research how viruses evolve. The goal, for the time being, is to slow the pandemic down to prevent its spread – no matter what version of the virus we’re experiencing.

  • Evolución viral, wikipedia. Recogido a 14 de abril en https://en.wikipedia.org/wiki/Viral_evolution
  • Cambio antigénico, wikipedia. Recogido a 14 de abril en es.wikipedia.org/wiki/Cambio_antigénico
  • Deriva antigénica, wikipedia. Recogido a 14 de abril en https://es.wikipedia.org/wiki/Deriva_antig%C3%A9nica
  • Comparison of the Mutation Rates of Human Influenza A and B Viruses, journal of virology. Recogido a 14 de abril en https://jvi.asm.org/content/80/7/3675