Gene Silencing May Stop AIDS Virus
Study Shows New Technique Has Potential as AIDS Therapy
WebMD News Archive
Fischl has seen a lot of promising AIDS therapies come and go, but she finds
the siRNA approach "intriguing" and would like to see it explored
One of the researchers doing this exploration is Ramesh K. Akkina, PhD,
professor of microbiology, immunology, and pathology at Colorado State
University, Fort Collins.
"The Shankar lab's finding is certainly an exciting development,"
Akkina tells WebMD. "This siRNA is a very interesting molecule that is
actually programming cells to deal with the virus."
Akkina notes that the Shankar/Kumar team is using direct injections of siRNA
constructs, an approach to gene therapy that would require repeat
administrations. Another approach uses a genetically engineered virus that
infects blood-forming stem cells and becomes a permanent part of their genome.
When these stem cells become T cells, they produce siRNA and are immune to HIV
"In the approach with the stem-cell gene-therapy approach, we are
programming blood-forming stem cells with anti-HIV siRNA so that the stem cells
are viable lifelong in the individual," Akkina says. "The
virus-resisting cells are produced on a daily basis."
Sponsored by Benitec, the firm developing this approach, a phase I safety
study of virus-delivered siRNA is under way at City of Hope Medical Center in
Kumar says her team's approach would avoid the pitfall of having a foreign
virus integrate into the human genome.
Both approaches hold promise for reaching the so-called "resting"
T-cells in which HIV is able to hide from current AIDS therapies. Reaching
these HIV reservoirs is the key to eliminating HIV from the body.
"These approaches could be used to purge the latently infected
cells," Akkina says.
"The advantage of siRNA is that you can deliver it into resting T
cells," she says. "So if these siRNA are present when the cell becomes
activated and starts to produce HIV, you have siRNA there ready to combat
Kumar and colleagues report their findings in the Aug. 22 issue of the
journal Cell. Kumar, an instructor at Harvard Medical School while
working in the Shankar lab, is now an assistant professor at Yale