Why are some caucasians immune to AIDS?

[Dinner]

I've seen numerous news reports that some where between 1%-10% of people of European decent have a genetic mutation which makes them immune to infections such as AIDS. My question is why? The standard explanation is that during the long dark ages and the medieval period the social services of the Roman Empire (running water, sewer systems, etc) and this, combined with the rise of long range trade linking Asia & Europe, made Europe a hot house of contagious diseases. For 500-1000 years Europe was racked by one epidemic after another, the worst of which was bubonic plague which killed 35% of the population, so in classic evolutionary theory those with mutations which help resist these disease survived and those most susceptible died.

My question/problem is that virtually all of these epidemics were bacterial in nature while AIDS is caused by a virus so why would bacterial epidemics help protect against viral epidemics when, I believe, the exact fashion a virus enters a cell is different from how a bacteria reproduces?

[Dinner]

Another interesting question is we know that middle eastern, South Asian, and East Asian cities which just as crowded and disease filled as European cities so why hasn't this genetic immunity popped up in those populations? Is it just that they had access to better medical care and so not as many people died so the evolutionary pressure was not as high or is there some other reason?

What was the death rate for things like bubonic plague in Asia? Was it not as high as the 35% in Europe so maybe not enough of them died to select for those who had partial or full immunity?

[chequita guevara]

Because of the Plague.

Mutations aren't just waiting around in the entire population to be switched on by an event. It was very likely a non-harmful mutation that just happened to confer immunity to plague. When the plague swept through Europe, where the mutation existed, those with the mutation survived, and were thus, better able to pass on their genes.

The fact that HIV is a virus and plague caused by bacteria is irrelevant. It could be that specific receptors in cells allow both parasites to invade host cells, and the mutation lacks that receptor, thus making them immune to invasion by HIV of plague.

[SlowwHand]

Read up. That would be the OP, right before your post.

[Ben Kenobi]

A phenomenon called coincidental immunity.

It's an adaptation that arises out of a mutation. Say someone gets a gene mutation that offers no benefit to them or another mutation that offers a survival benefit for something else. Later on down the line, that same mutation would protect against HIV, even with no contact with HIV prior. This is why genetic diversity is so important.

[Dinner]

Because of the Plague.

Which I spoke about. The question is why since bacterial and viral infections attack the human body in such different ways why would an attack by one select for resistance to both?

Edit: Ben, that's interesting. I will have to look that up.

[chequita guevara]

Read up. That would be the OP, right before your post.

Which I spoke about. The question is why since bacterial and viral infections attack the human body in such different ways why would an attack by one select for resistance to both?

Edit: Ben, that's interesting. I will have to look that up.

I DanSed you.

[Dinner]

Mutations aren't just waiting around in the entire population to be switched on by an event. It was very likely a non-harmful mutation that just happened to confer immunity to plague. When the plague swept through Europe, where the mutation existed, those with the mutation survived, and were thus, better able to pass on their genes.

Which is, of course, standard evolutionary theory we all know and are taught in school.

The fact that HIV is a virus and plague caused by bacteria is irrelevant. It could be that specific receptors in cells allow both parasites to invade host cells, and the mutation lacks that receptor, thus making them immune to invasion by HIV of plague.

OK, let's assume, as it seems, that the bacteria and the virus both attack the same receptors on cell membranes and so immunity to one grants immunity to both. That said, plague and other epidemics certainly occurred in China, India, and the mideast as well as in Europe so why is the immunity only observed in Europeans? We know that Asia certainly had/has a much larger human population which was/is no doubt more diverse then the European population then or now so theoretically they should have a much larger store house of mutations (positive, negative, and neutral) then the European population. Yet, supposedly, it is only 1%-10% of Europeans which have this immunity to AIDS. I find this confusing because both areas were subject to epidemic diseases so surely both must have been subjected to similar selective pressures.

The only thing I can come up with is maybe the better organized eastern empires (which didn't collapse the way the Roman Empire did) might have resulted in fewer deaths during epidemics and so the selective pressure was lower. That said plague and all those other diseases were there and those societies surely had tons of people die as well. Did just not enough of them get sick and die from epidemics?

[chequita guevara]

You are making the mistake of assuming the mutation arose in more than one place at once. I don't know the specifics, but my guess is that the mutation is relatively recent, and probably arose in Caucasians after we came to exist as a "separate" race.

We don't have immunity to malaria. That's an African trait. Why should anyone else have immunity to plague or HIV?

[chequita guevara]

You might wish to read Stephen Jay Gould's Ever Since Darwin. You'll get a better understanding of how such mutations arise and how they spread.

[Dinner]

Yes, AIDS is just one example. I know blacks have half the rate of bladder cancer as whites so obviously there are numerous examples which can be used.

[DaShi]

A phenomenon called coincidental immunity.

It's an adaptation that arises out of a mutation. Say someone gets a gene mutation that offers no benefit to them or another mutation that offers a survival benefit for something else. Later on down the line, that same mutation would protect against HIV, even with no contact with HIV prior. This is why genetic diversity is so important.

You're talking about evolution.

[DaShi]

I've seen numerous news reports that some where between 1%-10% of people of European decent have a genetic mutation which makes them immune to infections such as AIDS. My question is why? The standard explanation is that during the long dark ages and the medieval period the social services of the Roman Empire (running water, sewer systems, etc) and this, combined with the rise of long range trade linking Asia & Europe, made Europe a hot house of contagious diseases. For 500-1000 years Europe was racked by one epidemic after another, the worst of which was bubonic plague which killed 35% of the population, so in classic evolutionary theory those with mutations which help resist these disease survived and those most susceptible died.

For one they are not immune. They are resistant. The media has overhyped this. These people lack a receptor that HIV uses to bind to infect cells. The problem is that HIV has been shown to naturally switch to another receptor during late infections. Is this selection driven by it killing the cells with the prior receptor? There's still some debate.

My question/problem is that virtually all of these epidemics were bacterial in nature while AIDS is caused by a virus so why would bacterial epidemics help protect against viral epidemics when, I believe, the exact fashion a virus enters a cell is different from how a bacteria reproduces?

While this is nonsense, the missing receptor hasn't been proven to protect against bacterial epidemics. There are incidence where bacterial infections can help inhibit flu infections, and probably vice versa. As for the benefit of not having that receptor, the only other stuff I've heard is that such people tend to do better with organ transplants but have worse outcomes with West Nile Virus.

[DaShi]

Anyway, all this moot. The real reason is that HIV was designed in laboraroties at Penn State to wipe out black people in Africa. That it hit the gay community as well is just a happy coincidence.

[chequita guevara]

No, it's a side effect from the radiation from cell phones.