In the latest development, U.S. government scientists say they have discovered three powerful antibodies, the strongest of which neutralizes 91% of HIV strains, more than any AIDS antibody yet discovered. They are now deploying the technique used to find those antibodies to identify antibodies to influenza viruses.
The HIV antibodies were discovered in the cells of a 60-year-old African-American gay man, known in the scientific literature as Donor 45, whose body made the antibodies naturally. The trick for scientists now is to develop a vaccine or other methods to make anyone's body produce them as well.
Antibodies that are utterly ineffective, or that disable just one or two HIV strains, are common. Until last year, only a handful of "broadly neutralizing antibodies," those that efficiently disable a large swath of HIV strains, had been discovered. And none of them neutralized more than about 40% of known HIV variants.
But in the past year, thanks to efficient new detection methods, at least a half dozen broadly neutralizing antibodies, including the three latest ones, have been identified in peer-reviewed journals. Dennis Burton of the Scripps Institute in La Jolla, Calif., led a team that discovered two broadly neutralizing antibodies last year; he says his team has identified additional, unpublished ones. Most of the new antibodies are more potent, able to knock out HIV at far lower concentrations than their previously known counterparts.
HIV is a highly mutable virus, but one place where the virus doesn't mutate much is where it attaches to a particular molecule on the surface of cells it infects. Building on previous research, researchers created a probe, shaped exactly like that critical site, and used it to attract only those antibodies that efficiently attack it. That is how they fished out of Donor 45 the special antibodies: They screened 25 million of his cells to find 12 that produced the antibodies.
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