Double Stranded RNA May Be Able to ‘Silence’ Genes That Produce Proteins Necessary for HIV Infection, Replication
Short forms of double stranded RNA may be able to "silence" the genes that produce some of the proteins used by HIV to invade and infect human cells, a finding that may lead to new therapies for people already infected with the virus, according to a study appearing in yesterday's online edition of Nature Medicine, AP/Newsday reports. (Schmid, AP/Newsday, 6/2). RNA serves as a "messenger" that signals cells to produce certain proteins. Double stranded RNA is typically an indicator that a virus or other outside invader has entered the body and signals cells to switch off their own corresponding RNA sequence, thereby depriving the invading organism of a way of linking to the cell or of replicating once already in a cell. Nobel Prize winner Dr. Phillip Sharp of the Massachusetts Institute of Technology and colleagues created two types of double stranded RNA that matched HIV proteins that are associated with viral infection and replication. When the altered RNA coded for the infection protein was mixed with human immune cells in a petri dish, the cells reacted "dramatically," causing the rate of cell infection to fall "fourfold" (Agence France-Presse, 6/2). In addition, the RNA that was coded to stop replication was successful in lowering viral production. The process, known as RNA interference, has yet to be tried in humans or animals, but Sharp and colleagues said it offers "proof-of-principle" that the technology can be used for viral suppression.
Resulting Therapy 'Long Way' Off
Sharp said that an experimental drug using RNA interference is still a "long way" off but added that researchers are "excited" about the possibilities. A team led by Dr. John Rossi from the Beckman Research Institute at the City of Hope in Duarte, Calif., reported similar results using RNA interference last month in Nature Biotechnology (Russell, San Francisco Chronicle, 6/3). Scientists remained concerned that RNA interference may have side effects such as interfering with the "normal biological processes" and wonder if a proper vector can be found for delivering the altered RNA in humans. "[T]here are a lot of concerns as to how it would be applicable," Dr. Louis Mansky of Ohio State University, said, adding that he does not foresee the technique, on its own, being more successful than antiretroviral therapy (AP/Newsday, 6/2).