Fresh Approach to Combatting HIV Offers New Hope
A fresh high-tech approach to combatting the human immuno-deficiency virus (HIV) may one day offer new hope to people living with medication-resistant strains of the disease, Scientific American reported on Jan. 19.
A specially engineered RNA molecule attacks the virus' spread in two ways, blocking the virus' ability to infiltrate uninfected cells and suppressing HIV replication in cells that have already been infected. Because the approach relies on a combination of two sorts of RNA, people living with strains of the virus that have adapted and become resistant to pharmaceuticals currently used to manage HIV could eventually benefit from the treatment.
The Scientific American article reported that part of the engineered RNA "chimaera" (which combines two forms of RNA into a single "smart bomb" that affects only the virus, leaving healthy cells unharmed) prevents HIV from replicating itself inside of infected cells. The other form of RNA enables the "smart bomb" to get inside of cells, and also "neutralizes" HIV that has not yet entered healthy cells.
The RNA's "smart bomb" analogy comes from a researcher who co-authored a paper on the new approach. "You're only targeting what has to be targeted," said John Rossi, of the Duarte, Calif.-based Beckman Research Institute of the City of Hope.
The Scientific American article noted that the RNA chimaera has never before been tested in animals. Trials using specially created laboratory mice indicate that the treatment may be successful in human patients. The chimaera is not a magic bullet, however: if used for treating humans, the RNA combination would have to be administered weekly. Moreover, the treatment does not destroy cells, it merely prevents HIV from being able to replicate itself. If a treatment were created that could target infected cells selectively and destroy them while simultaneously preventing any new infiltration of cells, HIV could conceivably be cured. "What you want to do is start purging the infected cell population," said Rossi.
"What they've developed is a two-part warhead, and either part works very well," the university of Southern California's Keck School of Medicine's Paula Cannon said, reported the Pasadena Star-News on Jan. 23. "Rossi and his team have been working on strategies to stop HIV replicating using these very cutting-edge technologies based on RNA." Cannon said that the demonstration of the treatment's effectiveness in living animals was a "huge step."
But Cannon also offered a note of caution, pointing out that HIV is notorious for colonizing hard-to-reach places within the body's tissues. For that reason, even a version of the treatment that destroys already-infected cells may not constitute a cure for HIV. "It's highly unlikely to be 100-percent successful," said Cannon, explaining that hidden, dormant HIV cells would not "be touched by this therapy, or any sort of therapy we have now." Eventually, Cannon added, "the virus wakes up and kicks off the whole infection again."
It may be years before the new treatment can be used in human trials, the Pasadena Star-News said, because of funding restrictions and the need to graduate to trials with lab monkeys before any human subjects could undergo the new approach.