Question: do u think it is possible to spred a virus that could take over the body

Yes and no. 🙂 Viruses can do some pretty incredible things to bodies. Rabies, for example, can make infected animals very aggressive, which helps to spread the virus as infected animals bite each other and pass on the virus. One of the viruses I study, baculovirus, makes caterpillars climb a tree in the way that helps the virus spread itself. So yes, it’s definitely possible to spread viruses that make bodies do things they wouldn’t otherwise do.

With that said, Hollywood often uses viruses that take over the human body as plot tools; you can see this in many zombie movies. For example, the ‘Resident Evil’ series of movies uses the ‘T-Virus’ to explain why humans are suddenly walking around as zombies. I can tell you that this is much less likely (possibly even impossible) for a virus to do. For a virus to take over the human body like that would require a very complicated virus, one that could overcome the body’s defenses (which are really good at defending the body from stuff like that) and hijack a lot of *really* complicated machinery.

Viruses that make their host body do things usually control one thing about their hosts. The baculoviruses I mentioned above control the host caterpillars by monkeying with a moulting hormone (a substance that gets the caterpillars ready to shed their outer layer in order to grow). The difference between this and taking over a body entirely is enormous. The genomes of viruses, the set of genetic recipes that turn a virus’ genes into proteins that let a virus infect a body, are among the smallest known. There just isn’t room in there for all of the recipes that would be necessary to control a human body, especially if it kills the body first as many of the zombie viruses in movies do. Now the virus has to not only make the body do what it wants, it has to do a bunch of extra work to keep the body going at all!

To illustrate this, imagine that you had to write down a recipe (a genome) for controlling a little red wagon up a hill (https://www.radioflyer.com/wagons/little-red-wagon.html). It might look something like this:

1. Grab the handle.
2. Pull up the hill.

Here, controlling the wagon (the host) is relatively easy; you can take control of one thing, the handle, and make the wagon do whatever you want. A human body would be more like a car, though, and writing down a recipe to control a car up a hill is much harder. It might look something like:

1. Open the door.
2. Get into the seat.
3. Find the keys.
4. Put the key in the ignition.
5. Turn the key until the engine starts.
6. Find the gear shift and put the car in drive.
7. Disengage the emergency brake..

I’m at 8 steps, and I haven’t even driven anywhere yet! And this recipe doesn’t even take into account things like traffic, which would make it far more complicated.

Of course, that example simplifies things in a way that I would get slapped by other scientists for, but I hope it gives you an idea of how unlikely a virus that ‘takes over’ the body is.