Viruses are amazing.
We tend to break the world into things that are alive and things that are not alive, but the boundary between those two categories is mighty blurry. And the problem is that any definition that includes viruses in the “alive” category probably also includes many substances that are clearly not what we meant. Possibly even things that are not organic. In fact, if a virus is “alive” then your definition of alive probably includes some machines and even software. When we call self-replicating parasitic/malicious software a virus we might be more literal than we intend — the two are really not that different.
So a virus is basically a protective shell with some chemically active locations that contains a bunch of RNA. A kind of incomplete strand of DNA. That RNA is enough information to replicate the virus if you’re near the necessary component molecules and can find some replicating machinery. That is, as a virus, you have the instructions for replicating yourself but no factory. In fact the virus has no metabolism at all — it’s really somewhere between a machine and a highly differentiated chemical compound. It doesn’t breathe, it doesn’t eat, it doesn’t shit. It doesn’t use energy in any complex fashion. It’s just a complicated bit of matter, relatively inert.
But it’s not inert chemically. Its exterior has chemical probes that detect specific locations on its prey and exploit those locations — strictly chemically, mind you, though under a powerful enough microscope the line between chemical and mechanical also gets blurry — to penetrate the prey. This chemistry, once the reactions are complete, also cause the RNA to enter the prey. Let’s stop calling it prey: the prey is a particular kind of cell. Viruses are pretty specific in that there are only a few or even one kind of cell that each is equipped to assault with its chemical boarding grapnels and breaching charges.
Once the RNA is injected, the prey cell does all the work. And again, this is mostly chemistry: RNA reacts with other molecules present in the prey to start and complete a production process. Your own cell’s machinery, which are supposed to be for making more cells, use these alien instructions to make viruses instead. And the instructions for making a virus, this alien RNA, includes the instruction to make more RNA and put that in the new viruses. This is mind-blowing (to me at least) because this is all chemical. It’s just a machine that does what it does and someone slips it a new set of instructions and suddenly the machine is making more instruction-slippers complete with more instructions. But there’s no intent because there’s not even a metabolism let alone a brain or even a nerve. This little monster is a machine. Just a machine.
It’s not even a cell, really. It’s just a box with auto-grapplers and breaching-charge-chemistry, a chemical valve, and a ton of strips of instruction code.
Why does that even hurt you? A couple of things about this attack are a problem for you.
One of course is that energy you spend making viruses is energy you are not spending fixing and reproducing cells that are good for something.
Another is that the empty shells float around in your body and they aren’t supposed to be there. Viruses fill you up with virus-garbage. Imagine you are the sea and virus husks are plastic six-pack holders and shopping bags.
And of course once your immune system figures our there are invaders it starts all the anti-invasion processes, including inflammation, expulsion (coughing, sneezing, puking, and other horrible -ings), and fever. If your immune system is hard at work and the viruses aren’t dying then you are busy spreading the virus uselessly and also being slowly killed by your immune response since you can’t survive a very high fever for long. Your body really hopes the elevated temperature will kill the virus before it kills you. It’s a gamble and the evidence that it usually works is that it’s what we do and we’re not extinct.
COVID-19 likes fairly specific cells in your lungs. Its grappling hooks and breaching charges only work on those cells. That’s why the symptoms are respiratory and specific to the lungs. A cold attacks a more common set of cells throughout your respiratory system including your sinuses which is why those symptoms are broader. Those cells are also more resilient or less necessary than the ones COVID-19 targets. COVID-19 likes cells that are really important for breathing and also really bad when the region is inflamed (since that adds pressure and fluid in your lungs and as anyone who has breathed a beer knows, fluid does not belong in lungs).
But your body does learn to hunt these things. When you recover you don’t recover because the virus is tired — it will replicate, exponentially, until all of your targeted cells are dead from exhaustion if it can. But you build attack cells that can change their chemistry over time until they successfully target and destroy this invader. Once you have a successful breeding pool of attack cells, they hunt and disable the viruses. And your body remembers this, so next time you see the same virus, you are equipped for defense. Unless the virus changes even a fairly small amount, in which case you might have less or even no defense again, just like the first time.
Your attack system is not very responsible though. They just fuck up the attacker and move on. You still have all the virus-garbage to get rid of and so are still to some degree symptomatic until you shed all that garbage.
Viruses are machines. If they were much larger they would literally be mechanical, but at the scale they exist, mechanism is chemistry. But it’s not metabolism and thinking of them as alive blurs categories to the extent that “alive” starts to lose meaning.
We are under attack by a hegemonic self-replicating swarm.
Viruses are science fiction.