Study may boost nutrient's use against HIV

Tuesday, December 02, 2008
By David Templeton, Pittsburgh Post-Gazette

It has long been known that people infected with HIV/AIDS have lower levels of selenium in their bodies, with further evidence that supplements of the micronutrient slow the virus's progression.

Now a Penn State University researcher has explained how selenium effectively battles the human immunodeficiency virus, or HIV, that weakens the immune system and afflicts more than 33 million people worldwide.

K. Sandeep Prabhu, assistant professor of immunology and molecular toxicology, said his team's findings reveal for the first time how selenium succeeds in blocking replication of HIV by 10-fold or more.

The research appears this week in the Journal of Biological Chemistry.

"We hope this will be incorporated into the clinic, and this research will lead to new therapeutic interventions with selenium and selenium-dependent compounds," Dr. Prahbu said. "It could lead to a whole new line of research."

It also suggests the over-the-counter supplement could provide a cheaper way to combat HIV/AIDS in impoverished countries, especially in Africa.

"Most of the HIV population lives below the poverty line and most can't afford drugs," Dr. Prahbu said. "Selenium and selenium compounds are less expensive but still provide protection by decreasing the viral load."

The research, he said, should encourage wider usage of selenium in the United States, where health officials have been reluctant to prescribe it without understanding how it works.

Dr. Prabhu's research reveals that selenium, which the body uses to maintain normal metabolism, makes its way into selenoproteins via an amino acid known as selenocysteine.

Once a person is infected with HIV, the virus begins replicating and producing a Tat protein that causes inflammation in cells. But the body counters with the selenoprotein TR1 that upsets the chemical structure of Tat and reduces HIV's ability to replicate.

During the battle, TR1 degrades, so supplementation is necessary to restore the body's supply. It explains why people with HIV/AIDS who aren't taking selenium supplements have low levels in their system.

Dr. Prabhu's team isolated bloods cells from healthy human volunteers who did not have HIV and then infected the cells with the virus. Next they added tiny amounts of the selenium compound, sodium selenite, into the cell culture and inhibited HIV replication by at least 10-fold, which Dr. Prabhu said could be a low estimate. Once production of TR1 was reduced, HIV resumed dividing rapidly.

"Once we fully understand the function of these selenium proteins, it will give us a handle to come up with more effective drugs," Dr. Prabhu said.

Epidemiological data already suggested that people with HIV/AIDS who used selenium showed better health results.

"Now we're coming out with the mechanism of how it works," he said.
David Templeton can be reached at dtempleton@post-gazette.com or 412-263-1578.

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