Study: Key Protein ID'd in AIDS Infection

W A S H I N G T O N, Nov. 21 -- The AIDS virus uses a protein complex thatdoes housekeeping chores inside cells to spread disease to othercells of the body, researchers say.

Studies published today in the Proceedings of the NationalAcademy of Sciences report that a group of proteins calledproteasomes are used by HIV, the AIDS virus, to assemble new viralparticles and to spread those new particles to uninfected cells.

New Protein Target For Treatment

Ulrich Schubert of the National Institute of Allergy andInfectious Diseases said test tube studies show that blocking theaction of the proteasome proteins can reduce the spread of HIVinfection by about 98 percent.

Schubert, the first author of one study in PNAS, cautioned thatthe research was conducted only in test tubes, and it is not knownwhether the proteasome inhibitors would work against HIV in humans.

“We would never inject this drug into an HIV-infected person,because we do not know what would happen,” Schubert said.

The proteasome inhibitors will be tested in monkeys before anyhuman tests are considered. The animal studies could take months,Schubert said.

Cautious Optimisim

Dr. Jonathan W. Yewdell, an NIAID researcher and co-author ofthe study, said that although inhibiting proteasome shows promiseas a strategy for treating HIV, “It is possible that it may nothave any effect at all.”

He said the proteasome function is essential for healthy cells,and a drug that blocks that function could affect every cell in thebody.

“It is possible that the HIV-infected cells will be moresensitive or that there are effects against the virus before”healthy cells are affected by a proteasome inhibitor drug, saidYewdell.

Yewdell and Schubert said cancer researchers are experimentingwith proteasome inhibitors for the treatment of prostate cancer,and early studies have shown no side effects in cancer patients.

Proteins Destroy Old Proteins

Proteasome’s job inside the cell is to identify and destroy oldor unneeded proteins. Another PNAS study, by researchers atPennsylvania State University, suggests that a molecule calledubiquitin plays a key role in how viruses use the proteasomecomplex in a cell to make new viral particles. Still another PNASstudy, by researchers from the Dana-Farber Cancer Institute,Harvard Medical School and the University of Padua, Italy, alsodemonstrate that ubiquitin plays a role in HIV particle formation.