Mention on another thread of people who are immune to HIV led me to remember a story I heard a while back.
Problem is, my recollection is fragmentary, to say the least.
As far as I can remember, it seems that a particular genetic mutation causes the individual to be immune to the plague. While extremely rare, this gene obviously proved to be very useful during the great plague era.
It is thought there is a few million (?) people nowadays who carry the gene.
The strange part of the story is that the same gene supposedly provides immunity to HIV. Apparently studying this gene won’t help us with finding a treatment/vaccine.
Did I dream the whole thing up? Did I get it wrong? If not, how could the same gene affect two completely different afflictions (one caused by a bacillus, the other a retrovirus)?
I think you’re confusing two different theories/mutations.
The link JillGat gave talks about CCR5 mutations, which protect against HIV infection. There is some question as to wether this is an absolute protection, but it’s obviously pretty damn good. There is a weak (IMHO) link to plague infection regarding the CCR5 mutation, and that might have been what you were thinking of.
What you may have also been thinking of is this. There is a THEORY that a cystic fibrosis mutation may give you a advantage when infected with plague or cholera. This mutation affects how electrolytes are processed by the body, and MAY prevent electrolyte and fluid loss during plagues that have a high diarreahal problem. This theory came was tested in mice, which did show better resistance to injected cholera toxin when one copy of the cystic fibrosis gene was mutated.
The cystic fibrosis theory is, as far as I know, largely untested. It was advanced to explain why the mutation is so common, i.e. why it has not bred itself out of the population. I don’t have a cite right off, but I’ll try and find one.
vanilla: Actually, the odds are pretty good. A few years ago I heard about a study of married couples where one partner was HIV+ and it showed that in most cases the virus didn’t readily spread to the uninfected partner. I think it’s because HIV doesn’t spread very efficiently through vaginal intercourse in otherwise healthy people. Most of the sexual spread seems to happen either during anal sex or during vaginal intercourse where there are other STD’s involved that cause sores on the genitals.
HIV is spread when the virus is able to travel from the one host to another. It is not a very hardy virus. If you have sex with an infected partner, you not necessarily get infected.
There are several things that come into play. I may not cover all of them.
One- the person who is infected need the virus to be active. If the virus is dormit, it becomes less likely to spread. The key is less. We don’t have a lot of hard evidence, so a lot of this is guess work, but very educated guesses.
If a person has AIDS, he will have a very high chance of infecting his partner. As the HIV count is quite high.
Women are more likely than men to get it.
Anal sex is more likely than vaginal.
You can get it by oral sex.
You can get thru cuts.
You can get if you have other std cuz the other std will compromise your epidermal(skin) protection.
The HIV virus will stay in the woman’s vaginal area since it is warm and wet. A lot of bacteria lives there too. If the virus does not find its way into the blood stream, then you won’t get infected, but the virus could have made it, but your immune system was able to destroy the virus before your TCells built the antibodies.
AND the most scary thing of all is that you ARE infected with HIV but the tests just show negative!
Remember HIV tests are not tests to find the virus, but tests to look for presence of HIV antibodies.
I saw a program about this also, and I thought the reason for it being emphasized was the racial factor. The way I heard the theory presented was that the (possibly)protective mutation is much more common in people of European descent, due to the fact that so much of the population of Europe without this mutation was obliterated by the plague. That left a much smaller gene pool to restock, and increased the percentage of descendants having the mutation.
OT but food for thought, I also read something that said the entire human race is more closely related genetically than any two chimpanzees, because of our common origins from a very limited number of individuals. It just makes it easier for us all to wiped out by a single bug. /X:(/X\
Except for that, of course. And probably most siblings. And parents & their offspring. But other than that, and maybe grandparents, aunts, uncles & cousins, most definitely.