Chimps, AIDS, And Immunity

Anonymous Coward writes "Researchers at the Biomedical Primate Research Center in The Netherlands have come up with a theory as to why modern chimps don't develop AIDS and its variants. The chimps in the study were found to share a usually uniform cluster of genes in the area that controls their immune systems' defenses against disease. This lack of genetic diversity suggests that a lethal sickness attacked chimps in the distant past. The theory postulates that approximately 2 million years ago an AIDS-like epidemic wiped out a large portion of the chimpanzee population. Those that survived developed an immunity to AIDS and its variants. If this theory holds true it may explain why some humans who are repeatedly exposed to HIV don't get sick."

Comments

AIDS, mortality, and timing.

[Buck2]

My uncle died of AIDS (or complications thereof) just a few years before the cocktail treatments started showing efficacy in extending HIV+ person's lifespans.

I was a little young, so I didn't realize it until much later, but this was a pretty "in your face" demonstration of how timing, in the sense of where you are in the course of human technological development can have a serious impact on your expected longevity.

There are, of course, the obvious facts that a long, long time ago your life-expectancy would be 30 years, whereas now (depending on where you live) it might be near 80. This is a development over thousands of years, though.

It's a bit shocking to think that if my uncle had developed his complications a few years later he might still be around today. I've always taken solace in the fact that the same could be said of my father's friends who were drafted for Vietnam, or my grandfather's friends who died in Korea, etc.

Illnesses seem a bit "different", though. Wars are arguably preventable, illnesses kinda just happen. I'm hoping and hoping that startling achievements in fighting "natural causes" will reach some sort of threshold where we might be expected to live for a ridiculously long time. :)

Longevity treatments, anyone?

Re:AIDS, mortality, and timing.

[American AC in Paris]

Illnesses seem a bit "different", though. Wars are arguably preventable, illnesses kinda just happen.

Meaning absolutely no disrespect to either you or your late uncle, AIDS does not "kinda just happen"; nor, for that matter, do many other illnesses.

The vast majority of AIDS cases stem from sexual activity and shared needles. It is conceivable that, given enough education, focus and effort, AIDS could be effectively eradicated in the span of a couple of generations with technology that is currently available. AIDS is not something that just kinda turns up in your system one fine morning; is an epidemic that can be effectively prevented with some very basic safeguards.

Again, I say this neither to inflict pain nor insult on you and your family. Rather, I say this to combat the notion that AIDS "just kinda happens", a view that will cause more harm than comfort in the long run.

Re:AIDS, mortality, and timing.

[Buck2]

Actually, you are probably speaking from a position that benefits from hindsight.

If the latency period of HIV is up to ten years (which is the last I've heard of it), and if my uncle died in 1992 (which he did), then if we also give a few years of wasting away (I don't know when he first developed symptoms), then he could have been infected way back in the 70's.

There was little to no information about HIV at the time. Think about all of the people who were infected by blood transfusions and whatnot. We only know that these things need to be checked out now. For my uncle, who probably got it from sex, and for blood transfusion victims, the disease basically "did just happen".

The only way it could have been prevented, because the vector was unknown, and, actually the disease was practically unknown, would have been to not engage in sex. Hah.

Rather simple

[praedor]

It is actually rather simple why certain people can be repeatedly exposed to HIV and not become productively infected. HIV requires its target cells have two cell surface proteins in order to infect it. One is the basic CD4 T cell receptor. The other is one of two different types of chemokine receptor. There is the CXCR4 and CCR5 receptors. The names derive from a common amino acid motif found in these receptors in most people: for CXCR4 it is cysteine-any amino-cysteine-arginine. For CCR5 it is cysteine-cysteine-arginine. Most of the people who appear immune to the infection contain a mutation in the CCR5 receptor (I'm not familiar with the CXCR4 receptor vis a vis mutations and infection resistance). Thus, HIV can bind to CD4 but because of the mutation in CCR5 it cannot complete the process and fuse with the cell. No fusion, no infection.

This common form of resistance doesn't require any cluster of genes nor any mysterious genetic variation or evolutionary alteration.

Subject test group?

[broken.data]

I completely misread the last line as why some humans who are repeatedly exposed to HIV don't get sex. We are talking about code-monkeys, right?

Perhaps some misunderstanding...

[broken_down_programm]

"Those that survived developed an immunity to AIDS and its variants. " ...Uh, IANA genetecist, but I THINK the way it works is that those that ALREADY had the peculiar genetic combination that would equip them to survive SIV where the ones that SURVIVED. Through their offspring this combination came to prevail in the population today...

Re:I worked at the NCI

[anzha]

Ethical questions aside, So how difficult would it be to purposefully change this one gene in an embryo?

What else does this gene impact? Obviously it has been changed naturally in some people, so it may not have that much of an impact...

Sharing DNS with chimpanzees

[Junior J. Junior III]

First of all, we share roughly 97% of our DNS with chimpanzees.

Hey, now, that may be true, but I don't think ICANN would appreciate you categorizing them thusly.

of course!

[Scrameustache]

If this theory holds true it may explain why some humans who are repeatedly exposed to HIV don't get sick."

They are in fact shaved monkeys, and not people after all?

not scary at all

[g4dget]

If the theory of an ancient chimp epidemic would hold true for humans, he said, "the implications are pretty scary."

I don't see anything particularly scary about it: the fact that we have the data from chimps may well let us develop better drugs.

If the biologists are "scared" by the fact that 90% of a population may have been wiped out by a virus--well, welcome to the real world. Those things happen to real world species. Humans are particularly susceptible because of travel and high population densities, but we also have a public health system going for us.

Note, incidentally, that infectious mononucleosis probably was also devastating for human ancestors--very lethal and very easy to transmit. Today, it is a harmless disease only because of an odd quirk of the virus and the human immune system.

Life expectancy

[TFloore]

Learn something about how statistics are collected and how to apply them.

I don't dispute your basic statement that average life expectancy 200-300 years ago was about 30 years. However, you need to look at what that number means.

200-300 years ago a *lot* of people died of childhood diseases. Once you made it past about age 15, you had a reasonable chance of living to see 50, and 70 wasn't completely unreasonable for the non-poor.

The "average life expectancy of 30 years" combined with "most people that live past 18 live to see 50" means that a good third of all people never lived through childhood, and most of these died before age 9.

A large percentage of women died in childbirth also. (It's amazing how that percentage dropped drastically when doctors simply started washing their hands.)

When 1/3 of your population lives to average 5, and 1/3 of your population lives to average about 35 (those childbirth deaths for women pull their average down) and 1/3 of the population lives to about 55...

Gives you an average life expectancy of about 30.

But if you lived to see 15, you had a reasonable chance of living to see 50 and beyond.

We haven't really done too much to extend life. Our average life expectancy has gone up so drastically in the last 100 years because we have beaten most childhood diseases, and reduced the childbirth-related deaths in women.

Lies, damn lies, and statistics.

It's not so much that I object to people lying with statistics... just be aware when you are doing it, okay? :)

AIDS contracted through other means.

[fmaxwell]

Meaning absolutely no disrespect to either you or your late uncle, AIDS does not "kinda just happen"; nor, for that matter, do many other illnesses.

AIDS/HIV "just happened" to many people who received blood and blood products in medical procedures. Especially hard hit were those with hemophilia. They were stricken at a horrible rate.

Isaac Asimov's 1992 death from heart and kidney failure was a consequence of AIDS contracted from a transfusion of tainted blood during his December 1983 triple-bypass operation.

Babies are born with it, rape victims contract it, and people getting organ transplants are infected by it.

Let us not stigmatize everyone who is suffering with, or has died from, this horrible disease by painting with too wide a brush and categorizing the victims as drug addicts and people who engage in unsafe sex.