Developing HIV fighter

Researchers developed a form of RNA which silencesd the genes that play a role in HIV infection, potentially showing a new way to combat the virus that causes AIDS. The team used short forms of RNA - ribonucleic acid - that turn off genes vital for the production of proteins used by the virus to enter and infect cells. RNA carries the blueprint for constructing proteins.

Dr. Phillip Sharp, at the University of Texas, said that, if many obstacles can be surmounted this could be a basis for intervention in HIV treatment. The work was conducted in the laboratory, and problems to be solved include finding ways to deliver the RNA to cells in animals or humans, to ensure it would not interfere with normal biological processes and would not have side effects.

The work, reported Sunday in the online edition of the journal Nature Medicine, is a ``proof of concept,'' Sharp said. He won the 1993 Nobel Prize for the discovery of ``split genes,'' that changed how scientists look at evolution and advanced research on hereditary diseases, including some cancers. Dr. Louis M. Mansky of Ohio State University, who was not part of the research team, said the findings were interesting but he said ``there are a lot of concerns as to how it would be applicable.''

Mansky said there have been difficulties in getting similar strategies to work in clinical settings. In lab tests, the RNA reduced, but did not eliminate, the virus, and thus Mansky said it might be useful in addition to the current drugs used to combat AIDS.

RNA is present in most cells, carrying genetic information and operating in the production of proteins. In recent years scientists have discovered that double stranded RNA can silence genes in a process called RNA interference. The component that accomplishes this - small interfering RNA, or siRNA . Sharp's team made two different siRNAs that targeted cell surface proteins essential for the HIV virus to infect a cell. They targeted the parts of the virus that make the protein as well as a regulator protein.

According to Sharp, in both cases we were able to show that these small RNAs in cells would inhibit the infection by HIV,'' in laboratory work.The RNA interference process is a very new development in biological science and is quite exciting,'' he said. ``It will move out of the lab soon ... in the next several years.''