Two Strains of H.I.V. Cut Vastly Different Paths | Hacker News Reader

Two Strains of H.I.V. Cut Vastly Different Paths

nytimes.com

27 pointsevilsimon5 comments

The startling thought is that SIV has existed for a long, long time - I've read that it's tens of thousands of years old - and yet HIV only emerged in the last century or so.

The only explanation that makes sense to me is that HIV has emerged previously, but only in dead-end strains that have very low infectivity, rather like the HIV-1 groups N and P mentioned in the article. Whilst it makes sense to me, I have a feeling that it can't be right; seems a bit too easy or convenient to explain.

Are we victims of a million-to-one chance mutation, but a chance that become steadily more likely as time progressed?

Further, is it just a fact of life that we can - and should - expect another HIV-level-of-infection virus to emerge in the future?

> The only explanation that makes sense to me is that HIV has emerged previously, but only in dead-end strains that have very low infectivity, rather like the HIV-1 groups N and P mentioned in the article.

Or that modern innovations like transportation and so on made it possible for it to spread before it died out.

Exactly. This why Ebola hadn't spread the way it did until now. It was isolated to small remote villages.

>Are we victims of a million-to-one chance mutation, but a chance that become steadily more likely as time progressed? Further, is it just a fact of life that we can - and should >- expect another HIV-level-of-infection virus to emerge in the future?

Isn't this how viruses work? They can mutate and become more efficient at what they do.

Also if SIV has been around for thousands of years then it's not like it mutated overnight into a lethal strain of HIV.

That's not strictly "more efficient", at least in that notable zoonotic (https://en.wikipedia.org/wiki/Zoonosis) viruses tend to be noted because they're more lethal when they jump from an animal to humans. They've been observed to adapt over time to be less, or less quickly lethal, because those sorts of adaptational mutations allow more viral spread. Of course we don't always notice this because if e.g. an influenza were to adapt to the level of causing a "cold", we wouldn't necessarily notice.

See the other comment on how SIV just might have "mutated overnight", in that modern conditions allowed it to spread: https://en.wikipedia.org/wiki/HIV#Origins

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