Protein Discovered As Key to HIV Infection

Cutting it off in lab study keeps virus at bay

THURSDAY, Oct. 4, 2001 (HealthDayNews) -- Scientists may have discovered a way to stop the human immunodeficiency virus (HIV) from spreading from cell to cell.

HIV disrupts the normal processes that occur in our bodies' cells so that it can replicate and then escape from one cell to infect another. This process is known as "budding," and the researchers found that a protein named Tsg101 is essential to it. When they removed the gene that produces Tsg101, HIV was unable to bud from cells.

"Tsg101 is required for the virus to leave the cell," says one of the study's authors, Wes Sundquist, a professor of biochemistry at the University of Utah in Salt Lake City. "If we can get rid of Tsg101, we can stop it." Sundquist is quick to point out, though, that his team has not developed a drug that can knock out Tsg101, and that any medication that might come from this research would be years in the making.

Sundquist and his colleagues were able to remove Tsg101 from cells in the lab using a new technique called small interfering RNA. Cells that didn't produce Tsg101 kept HIV from budding -- the virus collected just under the surface of the cell, unable to push through.

Results of the study appear in the Oct. 5 issue of Cell.

Researchers from the biopharmaceutical firm Myriad Genetics, Inc. are hoping to develop a drug that can block the action of Tsg101. Although such a medication wouldn't cure HIV, it would keep the infection at bay and keep it from progressing to AIDS, much like the antiviral medications available today do. The scientists also suspect that other viruses escape from cells in a similar manner, so any drug developed could potentially be useful for other viral ailments.

According to the Centers for Disease Control and Prevention, more than 36 million people worldwide are currently infected with the HIV. Most cases of HIV eventually develop into AIDS, though the process can take years.

Frank Traganos, a professor of medicine and pathology at New York Medical College, says the researchers did a "nice job of proving the proteins that they named are necessary for virus budding in the case of HIV, and maybe in the case of other viruses."

But, he adds, "the question of how useful this is going to be is really up in the air." The problem, he says, is that the Tsg101 protein is a normally occurring protein and no one can yet know what would happen if a drug turns it off. "You have to be careful attacking the process in normal cells. There is a real chance of side effects," he says.

That doesn't mean developing a drug is an impossibility, however. Traganos points out that many of the chemotherapy drugs used to treat cancer attack normal cells, such as those needed for hair growth, but that the benefits of the drug outweigh the side effects.

What To Do

If youd like to see what HIV looks like when it buds from a cell, here's Sundquist's Web site.

For more information on HIV and AIDS, go to or the Centers for Disease Control and Prevention.

To learn more about the treatment of HIV and AIDS, check out the San Francisco AIDS Foundation.

SOURCES: Interviews with Wes Sundquist, Ph.D., professor of biochemistry, University of Utah, Salt Lake City; Frank Traganos, Ph.D., professor of medicine and pathology, and associate director, Cancer Research Institute, New York Medical College, Valhalla; Oct. 5, 2001, Cell
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