The micronutrient selenium, touted in some studies for cancer-fighting properties, may also slow the progress of the AIDS virus, says K. Sandeep Prabhu, assistant professor of immunology and molecular toxicology at Penn State.
In lab tests he and his colleagues conducted with human blood cells, Prabhu says, "We have found that increasing the expression of proteins that contain selenium negatively affects the replication of HIV. Our results suggest a reduction [of] at least tenfold."
K. Sandeep Prabhu
Computer model of Tat, a protein that helps HIV to replicate. Model was constructed with data from the NIH Protein database. Residues colored in "yellow" represent cysteine in the protein; while the turquoise color represents other residues.
Humans and animals need selenium to maintain normal metabolism. In the body, selenium becomes incorporated into so-called selenoproteins, which are known to be especially important in reducing the stress caused by infection, thereby slowing its spread.
When a virus infects a person, it quickly acts to degrade these selenoproteins so that it can replicate unhindered. "Since HIV targets the selenoproteins," Prabhu explains, "we thought that the logical way to deal with the virus is to increase the expression of such proteins in the body."
He and his team first isolated blood cells from healthy human volunteers who did not have HIV, and infected those cells with the virus. Next, they added tiny amounts of a selenium compound—sodium—selenite—into the cell culture to see the effect on viral replication.
Their results indicate that the addition of selenium inhibits the replication of HIV at least tenfold, compared to cell cultures in which no selenium is added. In contrast, when the researchers selectively reduced production of the selenoprotein TR1, they observed a three-and-a-half-fold increase in viral replication.
Prabhu believes that TR1 works by upsetting the chemical structure of Tat, a protein that helps the virus replicate. "Once we fully understand the function of these selenium proteins," he says, "it will give us a handle to come up with more effective drugs."
K. Sandeep Prabhu, Ph.D., is assistant professor of immunology and molecular toxicology in the College of Agricultural Sciences, ksp4@psu.edu. His work is funded partly by the National Institutes of Health.The findings described above were published in the Journal of Biological Chemistry,November 28, 2008. Co-authors of the paper include post-doctoral scholar Parisa Kalantari; visiting faculty member Kambadur Muralidhar; and graduate students Vivek Narayan, Ujjawal H. Gandhi, and Hema Vunta, all of Penn State; Satish K. Natarajan of the University of Nebraska; and Andrew J. Henderson of Boston University.