September 7, 2012
Macaques receiving a vaginal ring containing the experimental HIV drug MIV-150 were 83 percent less likely to become infected with simian HIV compared with those getting placebo rings, a study by researchers at the New York-based Population Council found.
Scientists have been looking at ways to help women at risk for HIV whose partners refuse to wear condoms. A 2010 large-scale study of a vaginal gel found it prevented infections among women in Africa, but a similar trial in November was halted because the gel was not working -- possibly because the women were not using it often enough. A vaginal ring could avert that problem.
"This proof-of-concept study confirms that the investment in vaginal rings as a delivery system for HIV prevention is paying off," said Naomi Rutenberg, vice president and director of Population Council's HIV/AIDS program.
The researchers inserted the rings either 24 hours or two weeks before exposing macaques to simian HIV and removed them immediately before or two weeks following exposure. Among the 17 monkeys that got the rings laced with MIV-150, two became infected, compared with 11 of 16 receiving the plain rings. Though the timing of insertion did not make a difference, monkeys whose rings were removed just before exposure were more likely to become infected than those whose rings were left in place.
MIV-150 is an antiviral developed by Medivir AB, a firm based in Huddinge, Sweden, and licensed to the Population Council in 2003.
The Population Council said it is working on a ring that could be left in place for up to three months and that also could potentially prevent other STDs and pregnancy. Further, the National Institutes of Health announced in July it is launching a trial of a ring that could involve almost 3,500 women in five countries.
[PNU editor's note: The study, "An Intravaginal Ring that Releases the NNRTI MIV-150 Reduces SHIV Transmission in Macaques," was published in Science Translational Medicine (2012;4(150):150ra123).]