Written by Loren Grush
Vaginal rings – such as the NuvaRing – have offered alternative contraceptive options for women looking to delay pregnancy or regulate their hormonal cycle. Now, a new type of vaginal ring could also help women prevent contracting sexually transmitted diseases.
Researchers from the Population Council, an international non-profit research organization based in New York City, have developed an ‘anti-HIV’ ring, which has successfully blocked HIV transmission in macaque monkeys. The ring works essentially like other vaginal rings, by constantly delivering a microbicide called MIV-150 inside the vagina.
An allosteric enzyme inhibitor, MIV-150 does not bind to the active site of HIV growth. Instead the microbicide binds to an enzyme away from the active site, which stops HIV from spreading.
“It essentially blocks HIV replication,” Tom Zydowsky, senior scientist at the Population Council’s Center for Biomedical Research and lead scientist of the study, told FoxNews.com. “It doesn’t change the shape of HIV, but it changes the shape of a key enzyme that HIV uses to reproduce. There are all of these steps in the HIV life cycle – one of them we’re blocking with MIV-150.”
Tested in the early 2000s, MIV-150 was found to be ineffective as an oral agent, because the drug was poorly absorbed into the bloodstream. The agent was also very actively cleared in mammals, so it’s low bioavailability and low half-life did not make it an attractive option for treatment.
However, by having MIV-150 constantly delivered in the localized area of the vagina, Zydowsky and his colleagues were able to overcome the obstacles the drug posed as an oral agent.
“The MIV-150 gets released into the vagina, and it works by getting absorbed into tissues where the infection starts,” Zydowsky said. “It then … latches on to some of the virus before it attacks the cells. It doesn’t have to be in the blood stream, it has to be more localized in the vagina.”