

Merck's AIDS vaccine fails, trials halted - jyrzyk
http://news.yahoo.com/s/ap/20070921/ap_on_he_me/aids_vaccine_fails

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ingenium
Does anyone know the details of how this particular vaccine worked? The
problem is that most companies are STILL approaching it as though it's a
traditional virus like chicken pox. HIV-1 has a defective DNA polymerase, so
everytime it replicates it introduces errors/mutations. This is why it changes
so quickly.

Most of these vaccines try to get the body to produce antibodies that
recognize the envelope protein. The envelope protein though is free to mutate
without changing the action of the virus. People who somehow naturally produce
antibodies making them immune to HIV have antibodies that target the active
sites of gp120 or gp41. In other words, they need to mimic the receptor that
HIV binds to in order to enter the cell. This area CANNOT mutate or else HIV
will cease to be infectious.

There are problems tricking the body into producing one particular antibody
(it's complicated, but it's based on how antibodies are generated). Therefore,
I think synthetic antibodies should be mass produced and injected. These will
target HIV-1 for destruction while also preventing it from being able to
infect CD4+ cells. The problem with this is that producing mass quantities of
antibodies is still very expensive.

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Elfan
Will the immune system accept a foreign antibody?

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ingenium
It depends. I would think that as long as the antibody is human, it SHOULD
recognize it. If it doesn't, there is no harm, it won't cause an allergic
reaction or anything. However, by targeting this region, the binding of the
antibody prevents the HIV from binding to the CD4 receptors. So even if the
immune system doesn't recognize it, it still disables the virus.

