Molecule engineered to attack HIV shows positive results
By ANIThursday, January 20, 2011
LONDON - A new study has found that an RNA molecule engineered to attack HIV in two different ways is showing positive results.
The molecule, which both curbs viral replication inside infected cells and neutralizes free-floating virus, could help patients who have developed resistance to HIV drugs, according to researchers, reports Nature.
The molecule, known as a chimaera, is composed of two different types of RNA: a small interfering RNA (siRNA), designed to enter infected cells and block the expression of two genes that HIV needs to replicate, and an RNA sequence known as an aptamer, which binds tightly to gp120, a protein found on the surface of HIV and HIV-infected cells. The aptamer has a dual role: it ferries the siRNA into infected cells and it neutralizes free-floating virus in the blood.
The chimaera is not new2, but this is the first time it has been tested in animals. To test the chimaera, the team used mice engineered to be susceptible to HIV. When the researchers injected mice with either the chimaera or the aptamer alone, the amount of virus circulating in the animals’ blood fell markedly. The chimaera, however, was more potent and suppressed the virus for a week longer than just the aptamer.
John Rossi, a molecular biologist at the Beckman Research Institute of the City of Hope in Duarte, California, a lead author on the paper, said that the molecule could be used as a stand-alone therapy, or in combination with other drugs that treat HIV. Because the antiviral effect of the chimaera lasts only about a week, patients would need to have regular injections.
The researchers found the siRNA in white blood cells known as lymphocytes of mice treated with the chimaera, indicating that the molecule can get where it needs to be. And when they measured the expression of the two genes targeted by the siRNA - tat and rev - in those same cells, they found a 75-90 pc reduction in expression after treatment. They also saw that the siRNA was cleaving the tat and rev genes in the right spots, an indication that the molecule worked the way it was supposed to.
The study has been published in Science Translational Medicine1. (ANI)
