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Carrots, Mice, Monkeys and AIDS, Oh My

Why isn't there an AIDS vaccine? Between mice and monkeys, the answer soon may be, 'There is.'
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    Original: received an op-ed submission today from Paul A. Kawata, the executive director of the National Minority AIDS Council, asking — on HIV Vaccine Awareness Day — why no HIV vaccine exists:

"An HIV vaccine would be a welcome addition to our current HIV prevention methods, and it's our best hope in controlling — and one day ending — the HIV/AIDS pandemic worldwide. This is particularly important in communities of color, which have been hardest hit by the AIDS epidemic since it began.

"According to the Centers for Disease Control and Prevention, more than 1 million adults and adolescents are living with HIV in the United States. Approximately 1 in 5 in this group (21 percent) is unaware of his or her infections. And according to the center's new campaign, Act Against AIDS, someone is infected with HIV every nine and a half minutes — that's more than 56,000 people every year. African Americans and Latinos alone account for nearly 50 percent and 18 percent of these infections, respectively.

"Obviously, an HIV vaccine would be helpful — and you're probably asking yourself: "Why don't we have one already?"

"The answer is simple: vaccines often take years to develop and testing through rigorous trials that include representatives from diverse populations. This ensures that the product distributed for general consumption will work for everyone."

Well, news from the lab suggests that several promising vaccines are being mapped out in laboratory whiteboards around the world, including one that makes use of our friends, mice. Researchers at Sweden's Örebro University have ginned up plants that produce the p24 protein in themselves and in their offspring. The p24 matters, explained dissertation author Ingrid Lindh in a release spotlighting the achievement:

"A major problem with the HIV virus is that it mutates rapidly and therefore exists in several different variants. In other words, it's not possible to create an effective vaccine that is based on the entire virus. Moreover, this would be far too risky. Instead, we have selected a protein, p24, that exists in all HIV viruses and looks roughly the same in the various virus lines."

So far so good. The next step was to feed mice some of the p24 plants, and see what happens. The hope was that the mice immune systems would create a defense against the foreign protein. This matters because once that immune response was activated, viruses sporting that protein would also be marked and hunted down by antibodies.

Lo and behold, the mouse immune systems worked as advertised.

"It is highly probable that the human immune system will respond in the same manner," Lindh said, "but this is not to say that this would be sufficient to provide complete protection."

And while p24 is common in HIV strains, the researchers plan to add more proteins to burnish the antibody reaction.

In the meantime, they're looking for the best plant to grow the vaccine in. Thale cress has shown promise, although carrots have their partisans, since it's a vegetable that's routinely eaten raw, i.e. without cooking dismantling the necessary proteins. Tobacco has already shown promise in research by others.

Meanwhile, researchers who began their studies on mice have shown that immunization for simian immunodeficiency virus, or SIV, might be possible by injecting genes that produce the antibodies directly into a recipient. As reported in the current online edition of Nature Medicine, the process skips the concept of allowing the body to develop its own response — as seen with the wonder-carrots above — in favor of dumping the genes right into a muscle and from there into the bloodstream. As a TV pitchman might say, "direct to you by cutting out the middleman."

"In essence," write the researchers, led by the University of Pennsylvania pediatrician Philip R. Johnson, "this strategy bypasses the adaptive immune system and holds considerable promise as a unique approach to an effective HIV vaccine."

The "promise" is big — of nine macaque monkeys in the trial, none developed simian AIDS and two-thirds seem fully uninfected by SIV.

As Johnson told The Associated Press:

"I'm not about to over-hype this. But we are continuing our work with monkeys in parallel with moving forward to begin human trials in two years, if everything goes perfectly with our work with the FDA to develop safety preparations, which is absolutely appropriate. And if the immunization trials work, then you have another few years to gear up. So, in the best of all possible worlds, you're looking at five years down the road for a practical benefit for patients. But, scientifically, we believe we are on the right track."

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