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Liquid poison? Visitors from space? What are viruses, really? Are they alive?

Coronavirus continues to increase the general public’s interest in public health and health sciences. Hundreds of data scientists are taking their chances at xls algorithms, datasets and dashboards and more and more people voice their opinions about the outbreak response, data privacy concerns or the economical measures adopted by country governments. Now that treatments and social distancing measures that intend to flatten the curve are more or less clear to everyone, people are starting to talk more about the virus itself. Are viruses alive? Are they intelligent? Are they just balls of fat? Here are a few concepts to demystify viruses, some very interesting beings.

vīrus means poisonous in Latin. They were called this way because in the early days, before they were actually discovered, scientist discovered that there was something smaller than bacteria that caused diseases. The issues only happened when cells divided, and whatever was causing the problems could not be seen, so they assumed they were caused some liquid, some kind of poison for the cells.

Viruses are not liquid! They are just very small and were very hard to see. They come in many shapes and cause diseases in humans, animals, plants, fungus and bacteria. Yes, viruses also affect bacteria, which is why they were once considered interesting as a way to treat diseases caused by bacteria. These efforts were abandoned when penicillin became widely available, but the challenge of antibiotic resistant bacteria is bringing this interest back.

One of the reason why people say that virus are not alive is that they can only reproduce inside of another cell. This is common to some bacteria like chlamydia too, so some scientist believe it is an evolution or an ability that was lost as viruses because used to reproducing only inside hosts. Some say this is not an evolution and that viruses have always existed, and some say that they are actually fragments of other chains of RNA or DNA that decoupled from their chains to form new beings.

In these last few days I heard that viruses are dead because they do not have DNA. Well, they usually have RNA, but it is true some viruses, such as the one that causes the mad cow disease (cause of an outbreak many of you may remember) is only a protein case without DNA or RNA. It is true that viruses do not have a metabolism or cells, and that they can not reproduce outside of a host, but they have genes, they reproduce and they evolve by natural selection.

Viruses are made of genetic material inside of a protein protective case. Sometimes they also have a lipid coating. These lipid and proteins layers protect the genetic material of the virus and protect it from being discovered by the inmune system.

Viruses are not smart, as they don’t really have a brain, but they evolve naturally and this means that the viruses we get are an improved version of an older virus, the grand-grand-grand-son of an old virus that was better at spreading and using hosts as other strains of its kind. The coronavirus we face today, COVID-19, descends from viruses that learnt to become very contagious using air to move from a host to another instead of fluids like ebola or HIV, and that took a longer time to their hosts so that they could spread the disease as much as possible.

So far COVID-19 is proving to be a challenging virus to defeat. It’s on us to use what we have (isolation measures, treatments and vaccines) and to come up with new solutions to fight coronavirus. No matter if it is dead or alive.

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