OK...Daft Question...

[Gawdzilla Sama]

Viruses do us a great deal of good by killing off the weakest among us.

Didn't you just have the flu?

[JacksSmirkingRevenge]

Thanks for the answers...Plenty to read there if/when I get around to it.
...Can't promise I'll understand any of it, mind.

[Svartalf]

meh, I'm still there in spite of having had about 30 to 45 viral infections over the last 25 years, counting only those that demanded bed rest, seeing a doctor and/or purpose bought medication

[FBM]

Viruses do us a great deal of good by killing off the weakest among us.

Didn't you just have the flu?

Yup. And I'm still here to talk about it.

[Gawdzilla Sama]

Are you sure about that?

[Tero]

More on viruses and sex
http://en.wikipedia.org/wiki/Evolution_ ... ementation

The viral eukaryogenesis (VE) theory proposes that eukaryotic cells arose from a combination of a lysogenic virus, an archaeon and a bacterium.

[Animavore]

Your DNA is roughly 50 percent virus. Viruses help drive evolution.

AIDS kills gays and black people. Some odious people may see that as good.

[mistermack]

How come there aren't any beneficial viruses like there are bacteria?

Just to hazard a simple answer, I would say that it's because viruses don't actually produce anything, except copies of themselves.
Bacteria actually do things, and produce products, that other creatures can use.

Viruses have an effect on their host, and can interfere, but don't generally produce any "stuff".

If you think that each living organism is the result of about four billion years of evolution, then they should be pretty well suited to their environment by now. So the chances of a virus producing a beneficial change in a host are low.

Not impossible though. It has probably happened in the past that a virus has made a change that has actually helped a host survive in some way. But what happens then is that the virus dna becomes so closely bonded to the host, that it just ends up as part of the organism's dna. It's passed on at the reproductive stage to the offspring.

So lots of human dna used to be virus, but you can't recognise it as such now.

[Azathoth]

Cowpox is pretty beneficial. Doesn't do much in humans and confers immunity against smallpox

[Pappa]

Some beneficial viruses have been found recently. The New Scientist ran an article and speculated more might be found soon, and suggested the reason none have been found up to now is that nobody ever thought of looking.

[JacksSmirkingRevenge]

Cowpox is pretty beneficial. Doesn't do much in humans and confers immunity against smallpox

Interesting. Didn't know that.

Some beneficial viruses have been found recently. The New Scientist ran an article and speculated more might be found soon, and suggested the reason none have been found up to now is that nobody ever thought of looking.

Searching....