HIV and Delta 32

[Roland98]

Originally Posted by viscousmemories

I saw this show on PBS tonight called Secrets of the Dead: Mystery of the Black Plague, which was all about a genetic mutation that sprung up around the time the Bubonic Plague appeared in medieval Europe. Apparently people with a single copy of this mutation were more likely to survive the plague, and people with two copies were frequently immune.

It seems that their descendants who still carry that mutation have the same resistance to HIV, even though the plague is a bacteria and HIV is a virus. It's pretty fascinating stuff that I've probably mutilated, so follow the link and read about it yourself, or wait for Roland to tell me if I've gone astray.

LadyShea asked me about that awhile back--previous thread. As I said there, it's not 100% certain that it's due to the black plague (and indeed, the mutation seems to pre-date that event), but that's one reason it could have spread within the population.

Though the bacterium that causes plague, Yersinia pestis, is a bacterium, it's an intracellular bacterium--it replicates within your cells. So in that way, it's similar to a virus like HIV, especially because both can infect white blood cells that generally serve to protect us from infection.

The resistance to AIDS is a pretty cool story. CCR5 is one receptor HIV uses to enter our cells, and the mutation seems to reduce the virus's ability to do so--hence, homozygotes for the mutated allele (those that have 2 copies of the delta 32 gene) appear to be resistant to HIV infection. Heterozygotes (those who have one normal and one mutated copy of the gene) can be infected, but at a lower rate than homozygotes for the normal allele.

One thing jumped out at me from the linked article: the lack of CCR5-delta 32 in Africa and Asia/East Asia. Wonder how much bearing, if any, that has on the rates of HIV infection in those geographies?

Rates are obviously higher there than in Europe and America, but how much of this is due to the CCR5 allele isn't known. Even in populations of European descent, it's not a very common mutation, so it's unlikely it plays a big role in infection rates.

In case I can't catch a re-run... did the program talk at all about how people with CCR5-delta 32 seem to be worse off than non-CCR5-delta 32 people when it comes to Hepatitis C? And did it broach the topic that maybe the "Black Death" in Europe wasn't bacterial at all, but... viral?

Why Hepatitis C? And there's no reason to think we have the etiology of the Black plague wrong. Viruses and bacteria often share cell receptors, since there's simply a limited number to go around.

The show itself is a rerun from a few years ago. This immunity is something that's been known for a while but isn't much talked about in the popular press.

Nope, it's not been discussed very much. But it is a good comeback to the AIDS-denyers who point to folks who have tested HIV+ but have gone 20 or 30 years without developing AIDS. We know genotype of both the virus and the host plays a big role in the development of a number of infections, and this is a perfect example of that.

[Dingfod]

Originally Posted by Roland98

Nope, it's not been discussed very much. But it is a good comeback to the AIDS-denyers who point to folks who have tested HIV+ but have gone 20 or 30 years without developing AIDS. We know genotype of both the virus and the host plays a big role in the development of a number of infections, and this is a perfect example of that.

Have these AIDS survivors been tested for the actual HIV virus or just for the antibodies? Perhaps I'm a bit behind the times here, I thought the only AIDS test was for HIV antibodies, not the virus itself. Set me straight.

[ms_ann_thrope]

Originally Posted by Roland98

Why Hepatitis C?

Could be Hep B as well, I guess, but whilst Googling I came across this abstract and thought it interesting. Could be entirely meaningless though.

And there's no reason to think we have the etiology of the Black plague wrong. Viruses and bacteria often share cell receptors, since there's simply a limited number to go around.

No argument from me that yersinia pestis causes bubonic plague. But I'm also intrigued by the theory that the "Black Death" that swept Europe in the 1300's was maybe actually a viral hemorrhagic fever and not bubonic plague. Or that two plagues could've been going on at the same time.

Microbes are neat, but I'm pretty out of the loop anymore, so forgive me if this has all been disproven.

[Roland98]

Originally Posted by ms_ann_thrope

Could be Hep B as well, I guess, but whilst Googling I came across this abstract and thought it interesting. Could be entirely meaningless though.

Ah, okay. It wouldn't be surprising if that mutation had varied effects on outcomes with other infectious agents, but the Hep C link isn't clear yet. There are other papers (such as this one) have found the opposite--that the CCR5 delta mutation increases clearance of Hep C. Jury's still out on that one.

No argument from me that yersinia pestis causes bubonic plague. But I'm also intrigued by the theory that the "Black Death" that swept Europe in the 1300's was maybe actually a viral hemorrhagic fever and not bubonic plague. Or that two plagues could've been going on at the same time.

Microbes are neat, but I'm pretty out of the loop anymore, so forgive me if this has all been disproven.

They could have been co-circulating, but from everything I've read, if there was a hemorrhagic fever outbreak at the time, it was probably just hemorrhagic versions of either yellow fever or smallpox, which were known to sporadically pop up across Europe. There's no evidence that there were large-scale epidemics of hemorrhagic illnesses distinct from bubonic plague during that period, but sure, the occasional case could muck things up as far as historical reporting.