Increasing the production of naturally occurring proteins that contain selenium in human blood cells slows down multiplication of the AIDS virus, according to biochemists from Penn State University.

The American researchers found that by increasing the expression of proteins that contain selenium reduces the viral replication of HIV by at least 10-fold. The findings have been revealed in the November 28 issue of the Journal of Biological Chemistry.

Selenium is a micronutrient that the body needs to maintain normal metabolism. Unlike other nutrients, which bind to certain proteins and modulate the protein's activity, selenium gets incorporated into proteins in the form of an amino acid called selenocysteine. Selenoproteins are especially important in reducing the stress caused by an infection, thereby slowing its spread.

Upon infecting a person, the virus quickly degrades selenoproteins so that it can replicate efficiently. It is unclear just how the virus is able to silence these proteins but K. Sandeep Prabhu, Penn State assistant professor of immunology and molecular toxicology, and his colleagues believe that stress inflicted on cells by the rapidly dividing virus, which produces a key protein known as Tat, is the likely culprit.

Tat is one of about 14 odd proteins produced by HIV during the first stage of infection. The job of these proteins is to trigger the expression of all the other genes that the virus needs to sustain itself. In addition, Tat also plays a key role in helping the virus replicate.

One of the proteins that targets Tat is a selenoprotein known as TR1.

Professor Prabhu says that since HIV targets the selenoproteins, his team thought that the logical way to deal with the virus was to increase the expression of such proteins in the body.

Results from the tests indicate that the addition of selenium inhibits the replication of HIV at least 10-fold, compared to cell cultures in which no selenium is added. When the researchers selectively reduced production of the selenium containing TR1 protein, they observed a 3.5-fold increase in viral replication.

Professor Prabhu believes that TR1 works by upsetting the chemical structure of Tat, which in turn reduces the virus' ability to replicate.

"Once we fully understand the function of these selenium proteins, it will give us a handle to come up with more effective drugs," said Prabhu, whose work is partly funded by the National Institutes of Health.

© NewsRoom 2008