NASHVILLE--Using a "hairpin ribozyme" gene, researchers at the University of California, San Diego, School of Medicine have managed to stop HIV infection in its tracks by dismantling the virus's RNA.
"We've shown that therapeutic genes can be passed on from parent cells to their offspring cells and that those progeny cells will be protected against HIV infection," said Anthony Ho, MD, PhD, speaking at the scientific sessions of the American Society of Hematology (ASH) meeting.
Virus vectors used to insert a therapeutic gene into target cells produce protection only for the lifetime of the cells that receive the gene therapy dose. But when the hairpin ribozyme gene is inserted into stem cells, via a standard viral delivery system, the progeny of these ribozyme-transduced cells also express the hairpin ribozyme gene, Dr. Ho noted.
When these treated cells were exposed in the lab to HIV, they did not become infected, said Dr. Ho, professor of medicine and director of stem cell transplantation, UCSD Medical Center.
The new treatment method, known as intracellular immunization, is based on work by Flossie Wong-Staal, PhD, professor of medicine, University of San Diego. She found that the hairpin ribozyme disables HIV-1 by cleaving its RNA like a molecular knife.
In the experiment, the researchers extracted CD34+ cells from human fetal cord blood and mobilized these cells by culturing them with growth factors so that the final blood sample was comprised of nearly 90% CD34+ cells. The hairpin ribozyme gene was inserted into this line of cells, which then went on to produce a new generation of macro-phage-like CD34+ cells that expressed the hairpin ribozyme gene and successfully resisted HIV infection.