The latest trial testing out a potential HIV vaccine in humans has flopped.
Drug maker Merck & Co. (who developed Gardasil- the HPV vaccine) said Friday that it was stopping enrollment and vaccination of volunteers taking part in the international study because the HIV vaccine being tested was clearly not doing its job.
24 of 741 volunteers who got the vaccine eventually became infected with HIV. 21 of 762 participants getting dummy shots also became infected with HIV (most of the volunteers were homosexual men or female prostitutes).
The Merck vaccine was the first to test a new strategy to prevent HIV infection by trying to get the body's immune system to make more killer T-cells to fight off the virus (HIV essentially destroys the immune system, which is why people who die of AIDS actually die from something else like pneumonia).
When the AIDS virus first made an outbreak in America in the '80s, I don't think anyone anticipated how difficult it would be to develop a vaccine for this. But, part of the problem is that HIV/AIDS is such a complicated disease, and the medical profession is still trying to understand exactly how it works.
So in the meantime, we just have to be extra careful about using condoms, and putting a cap on our sexual activity.
As a side-note- and this is positive- circumcision has been linked to a reduced risk of HIV transmission. To find out more, read this.
So boys, if you're not already circumcised, maybe that could be an option too. From what I've heard, the surgery doesn't keep you down for long (condoms still need to be used, though).
Here's a link to more information about the HIV vaccine study.
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Source: http://www.sciencedaily.com/releases/2007/10/071012080135.htm
Science Daily — The search for a vaccination against HIV has been in progress since 1984, with very little success. Traditional methods used for identifying potential cellular targets can be very costly and time-consuming.
The key to creating a vaccination lies in knowing which parts of the pathogen to target with which antibodies. A new study by David Heckerman and colleagues from Massachusetts General Hospital, publishing in PLoS Computational Biology, has come up with a way to match pathogens to their antibodies.
At the core of the human immune response is the train-to-kill mechanism in which specialized immune cells are sensitized to recognize small peptides from foreign pathogens (e.g., HIV). Following this sensitization, these cells are then activated to kill cells that display this same peptide. However, for sensitization and killing to occur, the pathogen peptide must be "paired up" with one of the infected person's other specialized immune molecules--an HLA (human leukocyte antigen) molecule. The way in which pathogen peptides interact with these HLA molecules defines if and how an immune response will be generated.
Heckerman's model uses ELISpot assays to identify HLA-restricted epitopes, and which HLA alleles are responsible for which reactions towards which pathogens. The data generated about the immune response to pathogens fills in missing information from previous studies, and can be used to solve a variety of similar problems.
The model was applied to data from donors with HIV, and made 12 correct predictions out of 16. This study, says David Heckerman, has "significant implications for the understanding of...vaccine development." The statistical approach is unusual in the study of HLA molecules, and could lead the way to developing an HIV vaccine.
Citation: Listgarten J, Frahm N, Kadie C, Brander C, Heckerman D (2007) A statistical framework for modeling HLA-dependent T cell response data. PLoS Comput Biol 3(10): e188. doi:10.1371/journal.pcbi.0030188
Note: This story has been adapted from material provided by Public Library of Science.
Fausto Intilla
www.oloscience.com
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