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Asked by anon-185977 to Verity, Trystan, Raquel, Danny, Catherine, Andy on 6 Nov 2018.
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Danny Ward answered on 6 Nov 2018:
Viruses evolve over time (over millions/billions of years) to adapt to their environments and their hosts. By chance, some viruses of a particular species will get natural changes to their genetic code called mutations. Most do nothing, or are worse for the virus. Some though will provide a ‘fitness advantage’ meaning they make the virus better at infecting and surviving. These viruses will be more likely to infect and pass on their genetic code with the changes in it compared to the other ones so this genetic information will be passed down to the next generation of viruses of that specific type. Some viruses infect things other than humans like animals, bacteria or plants and so will have a very different genetic code to allow them to do this.
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Trystan Leng answered on 6 Nov 2018:
Like all living things, viruses evolve. This means that over generations, they adapt to their surroundings, so that they have the best chance of survival, and lasting for another generation. Because the lifespan of a virus is much smaller than the lifespan of a human, they can evolve rapidly, adapting to the environment of a particular person’s body! Each time a virus evolves, this process is unique, so we end up with viruses with slightly different genetic makeups than any before them.
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Verity Hill answered on 6 Nov 2018: last edited 6 Nov 2018 5:49 pm
Danny and Trystan have answered this question really well already, but there’s a couple of things that I find very cool about viruses!
First is to do with the evolution that Danny and Trystan mention. What is cool about viruses though is that most of the ones that we are interested in (like Ebola, flu, and HIV) have a different type of genetic material to humans – instead of DNA, they have RNA. It doesn’t really matter what they are called, but the import bit is that RNA can change much faster than DNA can, because it doesn’t check for mistakes when it’s copying itself. This means that viruses “mutate” a lot faster than animals do, so they can adapt and avoid our defences very quickly – sometimes this happens during a single infection for a virus like HIV that lives in you for a long time!
The other thing is that when we find new viruses in humans, it’s because it has come from another animal. There are a lot of viruses that live in bats that jump into humans (like Rabies and Ebola), and HIV was originally a virus in chimpanzees. So the virus has been evolving in a different animal where we are less likely to spot it, and then we suddenly get a whole new disease when it jumps into us!
Comments
anon-185977 commented on :
Thank you so much for your replies! I had some idea about the evolution of viruses but now I thoroughly understand the whole process of mutations and fitness advantage when copying itself.
anon-186405 commented on :
what advice would you give to someone wanting to be a scientist