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- Why isn't a virus “alive”? 7 answers
I saw this fascinating article today about how HIV moves through a mouse host in real time.
It's common to hear a virus' activity described in the way the article does: with intent.
I have a hard time understanding this. Something is considered alive when it has a metabolism, takes in nutrients and expels waist. It has to have some kind of respiratory system and it's own reproductive mechanism. Although locomotion is optional, most forms of life have some form of getting around. Some plants are able to move somehow...
Viruses have no sensing organs and no method of locomotion. They cannot smell or see or move on their own. This means they have to be carried inside a cell or if free floating in a host's fluids, rely on random motions to get about.
In order to invade, as far as I understand this; they must essentially wait until they come into physical contact with a compatible target. At this point, their protrusions (I call them "keys") attach to a host cells "door" and they then inject their DNA.
Most (or all?) cells use Mitochondria for "power" so they can do things - like metabolize and reproduce. I've never seen a diagram of a virus that shows where it get's it's energy to power the 'injection' part of it's 'life cycle'.
How is this done?
In the mouse video, the HIV virus looks like it has a "plan" and that it knows how to select which initial cells to invade and then how to pick a good method of remaining hidden. How can this be when they have no sense organs? How can they "know" of other virus particles are being successfully attacked by the host?
This is incredible and incredibly complex.
I'm not a medical professional. I'm just a fascinated by-stander.