In a study in macaques, a vaginal ring that delivers the anti-viral drug MIV-150 blocked the transmission of HIV infection. This is the first study to prove the efficacy of this form of prevention, according to the Population Council.
The researchers fitted the macaques with vaginal rings that delivered the non-nucleoside reverse transcriptase inhibitor MIV-150, and then exposed them to a single dose of SHIV, a virus combining genes from HIV and SIV (the human and monkey forms of the virus). The rings protected the monkeys from infection whether they were inserted 24 hours or two weeks before infection, but they needed to stay in place after exposure to be effective.
"This study not only provides proof-of-concept for rings but it also expands potential microbicide options by giving us exciting new data on the efficacy of the anti-retroviral MIV-150. As we learned here, MIV-150 is highly effective at preventing infection when released from a ring," said Melissa Robbiani, Population Council's director of biomedical HIV research.
HIV is now much more treatable than it used to be, but the social and economic costs are still high, particularly in the developing world. If the Population Council's vaginal ring works as well in humans, it could protect women against infection and cut the transmission of HIV to children. And as it is expected to stay in place for up to three months, it could prove to be more acceptable than anti-viral gels or condoms, and easier to use. The system could also be used to deliver other drugs to prevent a range of sexually transmitted infections (STIs), and even act as a contraceptive as well.
The International Partnership for Microbicides (IPM) is also developing an anti-HIV vaginal ring that delivers the anti-retroviral drug dapivirine, and is carrying out two trials in women in Africa.
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