Study: HIV Becoming Less Deadly, Less Infectious

An anonymous reader writes: A new study (abstract) from Oxford University shows HIV is weakening as it evolves in response to our immune system. When the virus encounters somebody with a particularly strong immune system, it sacrifices efficiency in replication to gradually overcome those defenses. This causes it to take more time for the infection to cause AIDS. Professor Philip Goulder said, "It is quite striking. You can see the ability to replicate is 10% lower in Botswana than South Africa and that's quite exciting. We are observing evolution happening in front of us and it is surprising how quickly the process is happening. The virus is slowing down in its ability to cause disease and that will help contribute to elimination." Goulder added that the average time from infection to the onset of AIDS has increased by 25% over the past 10 years.

Comments

Raining on the parade

[javilon]

I hate to say this, but if the virus is changing in that direction, it means it is more effective at infecting people that way. That's the way evolution works.

I guess if the virus is low key for a long time, it is detected later and retrovirals are started later, so it gets more chances to infect someone. Also, if the virus damages the body less, or the damage is slowwer, there are more chances it is not treated, so again it gets more chances to infect.

While it is good news that VIH is becoming less deadly, I wouldn't like it to become a chronic infection slowly debilitating and eventually killing its hosts. That would cause it not to be treated at all in poor countries.

Contribute to Elimination?

[tomxor]

"The virus is slowing down in its ability to cause disease and that will help contribute to elimination."

Not sure if this is incorrectly phrased or i'm incorrect in my understanding of viral evolution... The virus has evolved to slow down the process of causing disease, surely this is because it is advantageous to the continuation of this virus, if the host dies too quickly they are less likely to pass on the virus. So how does this contribute to eliminating the virus? is it not the opposite? Longer infected lifespan == Greater chance of transmission.

How is this good?

[MobyDisk]

One of the most nasty things a disease can do is to slowly replicate without causing symptoms. These long incubation periods are why Ebola, Tuberculosis, and Rabies are so dangerous. It makes them hard to detect and gives the host time to travel and potentially infect others without either party knowing. By the time the symptoms manifest it is often too late. By contrast, a disease that produces symptoms immediately is easily detectable and the host seeks treatment. If it is really really fast, they die before they can pass it on, and such diseases quickly eradicate themselves.

I don't look forward to a world where AIDS only manifests after 30 years, but everyone has it.

Re:How is this good?

[silfen]

I don't look forward to a world where AIDS only manifests after 30 years, but everyone has it.

You mean like HPV, HSV, EBV, CMV, and hundreds of other viruses large parts of the population carry and live with? Not to mention all the bacteria and parasites that live inside and on us? One more persistent virus that doesn't cause disease in most people isn't going to make a hell of a lot of difference. HIV should hurry up and evolve already.

By contrast, a disease that produces symptoms immediately is easily detectable and the host seeks treatment. If it is really really fast, they die before they can pass it on, and such diseases quickly eradicate themselves.

Which is why evolution selects against them. You don't get a choice in the matter.

Re:Then again, maybe it _is_ good news.

[VitrosChemistryAnaly]

What we'd have then is a situation like SIV in which the virus doesn't cause disease in "natural" host organisms (such as chimpanzees) because the host can control virus replication. These people actually already exist and they're called "elite controllers". They are infected with HIV (for many, many years), but their immune system keeps the virus to almost undetectable levels. For them, HIV is harmless.

I work in immunology and the coevolution of host and virus to the point where it is harmless would be a Good Thing (TM).

disease progression has a genetic component

[madbrain]

I'm somewhat skeptical here. From my very small n=2 study, my husband and myself, infected the same year in 2006 (we both had HIV negative and positive tests that same year) with the same virus, as evidenced by genotype mutations test, I can tell you that my husband progressed from HIV to AIDS in less than a year, and had to go on antiretrovirals right away, whereas I didn't need medication for years and chose to remain without them for 4 years. I was in HIV controller studies. There was no change to my immune system on paper. But I was very tired, and I later chose to go on meds anyway. I had to drop out of the studies for this reason. I don't know what came of them. We are of different ethnicity - I am of caucasian and middle eastern descent; while my husband is asian; so our genetic are probably quite different.

It seems to me that this difference in disease progression between countries may have less to do with the virus itself evolving than it does with people's immune systems and genome evolving and becoming better able to deal with the virus.