Monday, August 14, 2006

More on HIV

So, it's a good question- why isn't there an anti-HIV vaccine by now? Surely the potential profits for the first individual to create one are an incentive. Think whatever you want about the drug companies, but all a researcher has to do is create a vaccine and sell it to the world at a slight profit to make a fortune. Surely, that's an incentive, right?

Apparently, the problem is the science of creating a vaccine. Being a novice at biology, I'm going to cut and paste the answer I found on AIDSmap:

"The doctors explain that HIV has three properties that have complicated the search for an effective vaccine. Firstly, HIV converts its genetic material from ribonucleic acid (RNA) into DNA after it infects cells, before hiding this DNA away within long-lived CD4 T-cells, ready to start producing more HIV particles at any time. This means that an effective HIV vaccine must be able to stimulate a long-lasting immune response to prevent new HIV production within the body. "

Which was what Patrick was saying about HIV hiding out in the body for years.

"Secondly, HIV damages the very immune cells that are needed for an effective vaccine; and thirdly, HIV is genetically diverse, with three main groups containing distinct clades, which are found at different proportions across the globe."

The Discovery Channel focused on the second problem last night. It's apparently difficult to destroy HIV without the immune system's help, and as HIV is sugar-coated (believe it or not) the body won't attack it, thinking it's supposed to be there. Then HIV weakens and finally destroys the immune system, which a vaccine would need to be healthy to work with.

"While vaccines for infections such as polio are designed to stimulate the body to produce antibodies, this approach has failed in HIV vaccine research, as the variability in the virus’s structure, both within and between patients, has resulted in responses to vaccines being too narrow and too weak."

From what I understand, a retrovirus can be startlingly diverse in structure. Supposedly, this is why we still can't cure the common cold.

"What’s more, the doctors point out, the two vaccines that have entered large phase III trials were designed to target the envelope proteins (gp120 and gp160) on the surface of the HIV particle. It is now understood that these proteins change shape and position when they bind to the receptors on the surface of a human T-cell, rendering the antibodies ineffective."

To get an image of the HIV virus, imagine a living rubic's cube that is constantly changing itself...

So, the attempts to create an artificial antibody against HIV haven't worked, but the idea is that we can create a vaccine that makes the cells themselves immune to HIV. From the sound of it, a vaccine is still our greatest hope against HIV, but is still far off. I still think our best hope for the future is in reducing infection rates, but a vaccine would be a godsend as well.

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