[evan_au]

If a virus has a DNA double spiral then surely it ... can mutate

Yes, some viruses have their genetic material stored as double-stranded DNA, but other viruses use single-stranded DNA, and many have RNA (mostly single-strand, but some use double-stranded RNA).
https://en.wikipedia.org/wiki/DNA_virus
https://en.wikipedia.org/wiki/RNA_virus

Viruses can mutate, which means they can evolve - but just because they can mutate does not make them alive. They need to have a living host that can provide most of the cellular equipment to manufacture proteins and copy genetic material in order to replicate the virus.

Back when I was at school, the official view was that viruses were not alive. But viruses are on the edge of being alive - they have some properties of living things, but not others, so I can see why different people could come to different conclusions.

The discovery of some giant marine viruses with a physical size and genome size approaching some bacteria have further blurred the distinctions.
https://en.wikipedia.org/wiki/Pandoravirus

[Origin]

What is the dividing line between living and nonliving?
I think the answer is simple, but not very satisfying.  There is no line, just a fuzzy area between the 2.

[Bored chemist]

A bacterium, on its own,  can reproduce; a virus, on its own, can't.

That's not very blurred.

[Origin]

A bacterium, on its own,  can reproduce; a virus, on its own, can't.

That's not very blurred.

But a virus can reproduce, it can be killed and it has DNA or RNA.  Just seems kind of fuzzy to me...

[Bored chemist]

But a virus can reproduce

No, it can not.
No matter how  long you sit and watch one, it will not reproduce.

it can be killed

No, it can not; that's why you see scientists talking about hand gel "inactivating" the virus.

it has DNA or RNA.

If it was cheap. I could use DNA to glue sawdust together to make chipboard, but  it wouldn't be alive.

[evan_au]

A bacterium, on its own,  can reproduce; a virus, on its own, can't.

A bacterium, by itself, will starve and/or boil, freeze, or explode.
- A bacterium needs a certain environment, including temperature, pressure, and a variety of organic compounds (mostly produced by other living bacteria).
- That's why bacteria like to live in a microbiome, as they all interact with each other, and produce things that others need
- That's why we can't grow around 95% of bacteria in the lab, because they are not self-sufficient - they depend on other living organisms to survive and thrive.

Similarly, a virus needs a microbiome to survice - and that environment includes its viral host
- I understand that the human microbiome has many viruses to keep it under control - if some particular microbe starts to take over, then bacteriophages targeting that microbe start to multiply, to keep it under control.
- It's when we "nuke" our microbiome with unnecessary antibiotics that some bacteria have no competition from other bacteria, and things can get really out of kilter...

Infection of a human is the common cold's method of reproduction...

[Bored chemist]

A bacterium, by itself, will starve and/or boil, freeze, or explode.

A bacterium in a Petri dish will do just fine.
But a virus won't do anything unless you add life.

[Origin]

A bacterium, on its own,  can reproduce; a virus, on its own, can't.

That's not very blurred.

I checked and apparently the majority of the biologists say that viruses are not alive.  When it comes to subjects I am not well versed in a go with the experts so I now agree that viruses are not alive (I still wonder though...)

[evan_au]

A bacterium in a Petri dish will do just fine.

I understand that around 95% of bacteria "species" in a Petri dish will not grow, no matter what mix of food molecules, trace minerals, vitamins etc they are fed.
- That's because they naturally live in a microbiome, as a community of bacteria with networks of food/waste processing and even signaling paths.
- That's why so-called pro-biotics are a bit of a joke, because they only contain the small fraction of gut microbes that can be grown in a Petri Dish (and scaled up to a large-scale fermenter vat).
- That's also one reason why finding new antibiotics has been a challenge - some interesting bacterial candidates have been found, and their genomes sequenced. But they can't be grown as a monoculture - something that is almost demanded by the medical approval authorities.

[Bored chemist]

All that shows is that for 95% or bugs, we have not yet identified their "vitamins".
People with pernicious anaemia didn't need to eat raw liver, they needed to eat vitamin B12.