HIV Digest	HIV Digest Archive

In a discovery that may help explain why as many as a quarter of AIDS patients eventually develop dementia, researchers report they have found the mechanism HIV uses to destroy brain cells. The research suggests that proteins produced by HIV turn on at least two specific biochemical pathways that hasten the natural death of neurons.

Unlike other brain infections, including meningitis and herpes, HIV in the brain causes very little inflammation or increase in white blood cells. Even so, "neurons die and the brain atrophies," said Dr. Roger Pomerantz, the new study's lead author and a virologist at the medical college of Thomas Jefferson University-Philadelphia.

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Fewer patients taking antiretroviral drug therapy develop dementia than patients not taking the drugs. It is thought that some unknown genetic differences may make some people more susceptible to the damage. No one can predict which HIV patients will develop dementia. Pomerantz and colleagues had previously found that certain HIV proteins are toxic to neurons. In the current study, they set up a controlled experiment to determine whether the body's natural toxins or the viral proteins were responsible for the high loss of brain cells in AIDS-related dementia. Most damage was due to the virus and the proteins, they found. They then removed the virus from some T-cells and treated brain cells with infected T-cells and normal T-cells. "The only thing that kills neurons was the virus. Once the virus was removed, nothing from the T-cells would kill neurons," Pomerantz said.

Editor's Note: from the Seattle-Post Intelligencer