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CAMBRIDGE, Mass. -- When people become infected by HIV, it's usually only a matter of time, barring drug intervention, until they develop full-blown AIDS. However, a small number of people exposed to the virus progress very slowly to AIDS — and some never develop the disease at all.
In the late 1990s, researchers showed that a very high percentage of those naturally HIV-immune people, who represent about one in 200 infected individuals, carry a gene called HLA B57. Now a team of researchers from the Ragon Institute of Massachusetts General Hospital, MIT and Harvard has revealed a new effect that contributes to this gene's ability to confer immunity.
A different scenario unfolds in people who have the HLA B57 gene. Using their computer model, Chakraborty and colleagues showed that, because those individuals' T cells are exposed to fewer self-peptides in the thymus, T cells with receptors that mediate strong binding to viral proteins via just a few important contacts are more likely to escape the thymus. This makes these T cells more cross-reactive to targeted HIV peptide mutants, because as long as those points in the viral proteins don't mutate, the T cells are still effective. The model also showed that once those T cells are released into the bloodstream, they can effectively attack HIV proteins, even when the virus mutates.
This model also explains why people with the HLA B57 gene have autoimmune problems: Their T cells are more likely to bind strongly to human peptides not encountered in the thymus.
Local Eyam lore tells befuddling stories of plague survivors who had close contact with the bacterium but never caught the disease. Elizabeth Hancock buried six children and her husband in a week, but never became ill. The village gravedigger handled hundreds of plague-ravaged corpses, but survived as well. Could these people have somehow been immune to the Black Death?
Dr. Stephen O'Brien of the National Institutes of Health in Washington D.C. suggests they were. His work with HIV and the mutated form of the gene CCR5, called "delta 32," led him to Eyam. In 1996, research showed that delta 32 prevents HIV from entering human cells and infecting the body. O'Brien thought this principle could be applied to the plague bacteria, which affects the body in a similar manner. To determine whether the Eyam plague survivors may have carried delta 32, O'Brien tested the DNA of their modern-day descendents. What he found out was startling. ...
Originally posted by Sinter Klaas
reply to post by Aeons
What's the difference ?
There is no reason to do a rapid test. Why do you need the results quickly? No one (I hope) is having a test done to bolster their self of self-confidence in stranger sex by next week. Nor are you a researcher grinding out 50 samples for a paper.
I would not doubt that there is a higher rate of error or dubious results from a rapid result.