Word: hiv
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Dates: during 1990-1999
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...Protease inhibitors are the cornerstone of our HIV therapy," Dr. Frederick Hecht of the University of California and San Francisco General Hospital told the conference. "People had hoped that PIs would be significant enough to make it difficult or impossible for the virus to be transmitted." Sadly, this patient, part of a study published in the New England Journal of Medicine, indicates otherwise. It is yet another reminder to scientists that a cure for AIDS still dances well beyond their reach -- and that a vaccine, now more than ever, is the field's Holy Grail...
First, some background. Scientists have long known that HIV is devilishly effective at fending off antibodies lobbed at it by the body's immune system. One way the virus does that is by mutating rapidly, changing the various amino acids that make up its outer shell and thus forcing the body to churn out millions of new antibodies, all of which may become ineffective with the next mutation. Some parts of the virus don't change, however; if they did, HIV would rapidly lose its power to infect. If scientists understood more about those parts, they could use them...
Similarly, AIDS researchers knew that HIV penetrates healthy immune cells by latching onto two different "locks" on the cells' surface, the so-called chemokine and CD4 receptors, using a protein "key" called gp120. But what those locks looked like and how the HIV key opened them were a mystery...
...result is a detailed, computer-generated snapshot of the HIV infection process that is as starkly beautiful as it is informative. The picture shows, for example, that some of the virus' most stable--and therefore vulnerable--structures are either located at the bottom of crevices, where the relatively bulky antibodies of the immune system can't reach them, or obscured by great forests of sugar molecules. One particularly attractive target comes out of hiding only in that brief moment after gp120 latches onto the CD4 receptor and before it attaches to the chemokine receptor--much too briefly for the immune...
Just because HIV can outfox the immune system, however, doesn't mean it will always outmaneuver drug developers. Most drugs are very small molecules, much smaller than antibodies. Properly designed drugs might be able to infiltrate some of those crevices in HIV's outer walls. There's no guarantee that such an approach will work. But it's certainly easier to try when you have a picture in front of you showing you where to begin...