New study suggests why vaccines directed against cancer, HIV ...( COLUMBIA Mo. Researchers from the U...),Health

COLUMBIA, Mo. Researchers from the University of Missouri and Imperial College London have found evidence suggesting why vaccines directed against the virus that causes AIDS and many cancers do not work. This research is being published in the Dec. 14 edition of The Journal of Biological Chemistry.

In research spanning more than a decade, Gary Clark, associate professor of Obstetrics, Gynecology and Womens Health in the MU School of Medicine, and Anne Dell, an investigator at Imperial College London, found that HIV, aggressive cancer cells, H. pylori, and parasitic worms known as schistosomes carry the same carbohydrate sequences as many proteins produced in human sperm.

Its our major Achilles heel, Clark said. Reproduction is required for the survival of our species. Therefore we are hard-wired to protect our sperm and eggs as well as our unborn babies from any type of immune response. Unfortunately, our results suggest that many pathogens and tumor cells also have integrated themselves into this protective system, thus enabling them to resist the human immune response.

During the initial stages of life, the body goes through a process where it self-identifies, determining which cells and proteins belong in the body, so it can detect those that do not. After this time, anything foreign is deemed as dangerous, unless the immune system is specifically told to ignore those cells and proteins. This situation arises primarily during reproduction.

When sperm are made, they specifically label their glycoproteins with Lewis carbohydrate sequences, a specific chain of carbohydrates. When these foreign sperm enter the female body, the females immune system does not recognize them as foreign probably because of these Lewis sequences. Similarly, the unborn baby also could be seen as foreign by the mothers immune system, but she produces other types of glycoproteins that likely block any type of immune response in the womb. These
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