Commentary from the CDC HIV/STD/TB Prevention News Update 05/03/02:
HIV can be stopped in its tracks by using gene therapy to tell infected cells how to prevent the virus from replicating, researchers in Los Angeles said on Thursday. "This could be the smart bomb in our arsenal," said John Rossi, PhD, chairperson of the Division of Molecular Biology at City of Hope Cancer Center and lead author of the study published in the May issue of Nature Biotechnology (2002;20;5:500-505).
The findings of the gene therapy study shows that small pieces of RNA can prevent HIV from growing in cells. "This is a new form of target-specific destruction," Rossi said, referring to a relatively new class of drugs that use molecular technology to block pathways associated with disease.
RNA is the intermediary between DNA, or the gene, and the product that it makes. "This system functionally destroys the gene product," Rossi said. By analyzing the genetic sequence of HIV, his team found two proteins the virus makes once it enters a cell and starts to replicate. "We can prevent the virus from producing the proteins. It's like a light with no light switch," Rossi said.
The small pieces of RNA, called siRNA, that get an infected cell to attack HIV can't be activated in the body because of an overriding mechanism. In order to get the body to make the siRNA, bone marrow would be taken from patients, combined outside of the body with genes that make the siRNA, and then reintroduced into the patient's bone marrow where new cells are continuously generated. "The body will repopulate with cells that protect against HIV," Rossi said. So far, the experiments have only been done in a petri dish, but the City of Hope researchers expect to begin testing the gene therapy system in human AIDS patients by late this year or early next year.
(CDC HIV/STD/TB Prevention News Update 05/03/02)
