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(HEALTH) READ: New Antibodies for HIV: Fresh Hope for a Vaccine?…

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Source: TIME

www.time.com_The HIV-1 virus appears under a microscope._hiv_virus_0901_000Scientists probably know more about HIV than any other pathogen, but despite that fact, they have had frustratingly little success in applying their knowledge toward a vaccine against the virus.

Now, after more than 15 years of trial and error in the field, researchers at the Scripps Research Institute and the International AIDS Vaccine Initiative (IAVI) report they have discovered two powerful new antibodies to HIV, which may potentially lead to the development of a way to immunize against the virus. (See TIME’s photo essay “Access to Life.”)

While the new antibodies are not the first of the so-called broadly neutralizing antibodies that have been isolated from HIV-positive patients, they appear, at least in the lab, to be 10 times more effective at disarming the virus than earlier versions. They are also effective against a broad array of HIV strains that span nearly every continent, from Europe and North America to Asia and Africa. That would make them ideal candidates for a new vaccine — one that could actually protect people from becoming infected with HIV at all.

In a way, it’s a back-to-the-future approach. Vaccines, including many of the familiar ones that target childhood diseases such as measles and mumps, work by training the immune system to generate antibodies against a foreign bacteria or virus. Made by immune cells known as B lymphocytes, these antibodies bind to specific portions of a virus and then hamper that virus from infecting healthy cells. Eventually, the piggybacked antibody also tags the invading virus for destruction by other immune cells, known as T cells. (See TIME’s AIDS covers.)

“We looked at 162 different [HIV] viruses, and these antibodies neutralized 120 to 130 of strains from all across the world,” says Dennis Burton of Scripps, the lead author of the study, published in the Sept. 4 issue of Science. “They certainly don’t get everything. But if you are able to get 80% or more of viruses circulating out there with one single antibody, that’s terrific. That’s really, really good, considering how variable these viruses are.”

That variability has been the biggest challenge for HIV vaccinemakers. HIV mutates so rapidly once it finds a new home in an infected patient that it’s hard for researchers to keep pace and target the portions of the virus that are conserved. It was a lesson that Merck learned the hard way in 2007, when trials of its promising AIDS-vaccine candidate not only failed to protect people from acquiring HIV but in fact appeared to raise the risk of infection in inoculated people, compared with those who did not get the vaccine. (It’s not clear why Merck’s compound failed so miserably, but researchers believe it may have to do with the vector, an inactivated cold virus, that was used to ferry the immunity-triggering HIV proteins into the body; some people may have developed enough natural tolerance to the common-cold virus that their immune system did not react to it, or to the viral payload piggybacked on it, at all.) READ MORE

Written by dnnnewshound

September 3, 2009 at 3:51 pm

Posted in Uncategorized

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